| 213 |
Accessibility Through Semantic HTML |
Working on Better, a tracker blocker, I spend an awful lot of my time with my nose in other people’s page sources. I’m mostly there looking for harmful tracking scripts, but often notice the HTML on some of the world’s most popular sites is in a sad state of neglect.
What does neglected HTML look like? Here’s an example of the markup I found on a news site just yesterday. There’s a bit of text, a few links, and a few images. But mostly it’s div elements.
<div class="block_wrapper">
<div class="block_content">
<div class="box">
<div id="block1242235">
<div class="column">
<div class="column_content">
<a class="close" href="#"><i class="fa"></i></a>
</div>
<div class="btn account_login"></div>
Some text <span>more text</span>
</div>
</div>
</div>
</div>
</div>
divs and spans, why do we use them so much?
While I find tracking scripts completely inexcusable, I do understand why people write HTML like the above. As developers, we like to use divs and spans as they’re generic elements. They come with no associated default browser styles or behaviour except that div displays as a block, and span displays inline. If we make our page up out of divs and spans, we know we’ll have absolute control over styles and behaviour cross-browser, and we won’t need a CSS reset.
Absolute control may seem like an advantage, but there’s a greater benefit to less generic, more semantic elements. Browsers render semantic elements with their own distinct styles and behaviours. For example, button looks and behaves differently from a. And ul is different from ol. These defaults are shortcuts to a more usable and accessible web. They provide consistent and well-tested components for common interactions.
Semantic elements aid usability
A good example of how browser defaults can benefit the usability of an element is in the <select> option menu. In Safari on the desktop, the browser renders <select> as a popover-style menu. On a touchscreen, Safari overlays the same menu over the lower half of the screen as a “picker view.”
Option menu in Safari on macOS.
Option menu picker in Safari on iOS.
The iOS picker is a much better experience than struggling to pick from a complicated interface inside the page. The menu is shown more clearly than in the confined space on the page, which makes the options easier to read. The required swipe and tap gestures are consistent with the rest of the operating system, making the expected interaction easier to understand. The whole menu is scaled up, meaning the gestures don’t need such fine motor control. Good usability is good accessibility.
When we choose to use a div or span over a more semantic HTML element, we’re also doing hard work the browser could be doing for us. We don’t need to tie ourselves in knots making a custom div into a keyboard navigable option menu. Using select passes the bulk of the responsibility over to the browser.
Letting the browser do most of the work is also more future-friendly. More devices, with different expected interactions, will be released in the future. When that happens, the devices’ browsers can adapt our sites according to those interactions. Then we can spend our time doing something more fun than rewriting cross-browser JavaScript for each new device.
HTML’s impact on accessibility
Assistive technology also uses semantic HTML to understand how best to convey each element to its user.
For screen readers
Semantic HTML gives context to screen readers. Screen readers are a type of assistive technology that reads the content of the screen to the person using it. All sites have a linear page source. Sighted visitors can use visual cues on the page to navigate to their desired content in a non-linear fashion. As screen readers output audio (and sometimes braille), those visual cues aren’t usable in the same way.
Screen readers provide alternative means of navigation, enabling people to jump between different types of content, such as links, forms, headings, lists, and paragraphs. If all our content is marked up using divs and spans, we’re not giving screen readers a chance to index the valuable content.
For keyboard navigation
Keyboard-only navigation is also aided by semantic HTML. Forms, option menus, navigation, video, and audio are particularly hard for people relying on a keyboard to access. For instance, option menus and navigation can be very fiddly if you need to use a mouse to hover a menu open and move to select the desired item at the same time.
Again, we can leave much of the interaction to the browser through semantic HTML. Semantic form elements can convey if a check box has been checked, or which label is associated with which input field. These default behaviours can make the difference between a person being able to use a form or leaving the site out of frustration.
Did I convince you yet? I hope so. Let’s finish with some easy guidelines to follow.
1. Use the most semantic HTML element for the job
When you reach for a div, first check if there’s a better element to do the job. What is the role of that element? How should a person be interacting with the element?
Are you using class names like nav, header, or main? There are HTML5 elements for those sections! Using specific elements can also make writing CSS simpler, and ensure a consistent design with minimal effort.
2. Separate structure and style
Don’t choose HTML elements based on how they’re styled in your CSS. Nowadays, common practice is to use class names rather than elements for CSS selectors. You’re unlikely to wrap all your page content in an <h1> element because you want all the text to be big and bold. Still, it can be easy to choose an HTML element because it will be the easiest to style. Focusing on content without style will help us choose the most semantic HTML element without that temptation. For example, you could add a class of .btn to a div to make it look like a button. But we all know that only a button will really behave like a button.
3. Use progressive enhancement for enhanced functionality
Airbnb and Groupon recently proved we’re not past the laziness of “this site only works in X browser.” Baffling disregard for the open web aside, making complex interactive experiences work cross-browser and cross-device is not easy. We can use progressive enhancement to layer fancy or unsupported features on top of a baseline “it works” experience.
We should build the baseline experience on a foundation of accessible, semantic HTML. Then, if you really want to add a specific feature for a proprietary browser, you can layer that on top, without breaking the underlying experience.
4. Test your work
Validators are always valuable for checking the browser will be able to correctly interpret your markup. Document outline checkers can be valuable for testing your structure, but be aware that the HTML5 document outline is not actually implemented in browsers.
Once you’ve got something resembling a web page, test the experience! Ensure that semantic HTML element you chose looks and behaves in a predictable manner consistent with its use across the web. Test cross-browser, test cross-device, and test with assistive technology. Testing with assistive technology is not as expensive as it used to be, you can even use your smartphone for testing on iOS and Android. Your visitors will thank you!
Further reading
Accessibility For Everyone by Laura Kalbag
HTML5 Doctor
HTML5 Accessibility
An overview of HTML5 Semantics
HTML reference on MDN
Heydon Pickering’s Inclusive Design Checklist
The Paciello Group’s Inclusive Design Principles |
2017 |
Laura Kalbag |
laurakalbag |
2017-12-15T00:00:00+00:00 |
https://24ways.org/2017/accessibility-through-semantic-html/ |
code |
| 234 |
An Introduction to CSS 3-D Transforms |
Ladies and gentlemen, it is the second decade of the third millennium and we are still kicking around the same 2-D interface we got three decades ago. Sure, Apple debuted a few apps for OSX 10.7 that have a couple more 3-D flourishes, and Microsoft has had that Flip 3D for a while. But c’mon – 2011 is right around the corner. That’s Twenty Eleven, folks. Where is our 3-D virtual reality? By now, we should be zipping around the Metaverse on super-sonic motorbikes.
Granted, the capability of rendering complex 3-D environments has been present for years. On the web, there are already several solutions: Flash; three.js in <canvas>; and, eventually, WebGL. Finally, we meagre front-end developers have our own three-dimensional jewel: CSS 3-D transforms!
Rationale
Like a beautiful jewel, 3-D transforms can be dazzling, a true spectacle to behold. But before we start tacking 3-D diamonds and rubies to our compositions like Liberace‘s tailor, we owe it to our users to ask how they can benefit from this awesome feature.
An entire application should not take advantage of 3-D transforms. CSS was built to style documents, not generate explorable environments. I fail to find a benefit to completing a web form that can be accessed by swivelling my viewport to the Sign-Up Room (although there have been proposals to make the web just that). Nevertheless, there are plenty of opportunities to use 3-D transforms in between interactions with the interface, via transitions.
Take, for instance, the Weather App on the iPhone. The application uses two views: a details view; and an options view. Switching between these two views is done with a 3-D flip transition. This informs the user that the interface has two – and only two – views, as they can exist only on either side of the same plane.
Flipping from details view to options view via a 3-D transition
Also, consider slide shows. When you’re looking at the last slide, what cues tip you off that advancing will restart the cycle at the first slide? A better paradigm might be achieved with a 3-D transform, placing the slides side-by-side in a circle (carousel) in three-dimensional space; in that arrangement, the last slide obviously comes before the first.
3-D transforms are more than just eye candy. We can also use them to solve dilemmas and make our applications more intuitive.
Current support
The CSS 3D Transforms module has been out in the wild for over a year now. Currently, only Safari supports the specification – which includes Safari on Mac OS X and Mobile Safari on iOS.
The support roadmap for other browsers varies. The Mozilla team has taken some initial steps towards implementing the module. Mike Taylor tells me that the Opera team is keeping a close eye on CSS transforms, and is waiting until the specification is fleshed out. And our best friend Internet Explorer still needs to catch up to 2-D transforms before we can talk about the 3-D variety.
To make matters more perplexing, Safari’s WebKit cousin Chrome currently accepts 3-D transform declarations, but renders them in 2-D space. Chrome team member Paul Irish, says that 3-D transforms are on the horizon, perhaps in one of the next 8.0 releases.
This all adds up to a bit of a challenge for those of us excited by 3-D transforms. I’ll give it to you straight: missing the dimension of depth can make degradation a bit ungraceful. Unless the transform is relatively simple and holds up in non-3D-supporting browsers, you’ll most likely have to design another solution. But what’s another hurdle in a steeplechase? We web folk have had our mettle tested for years. We’re prepared to devise multiple solutions.
Here’s the part of the article where I mention Modernizr, and you brush over it because you’ve read this part of an article hundreds of times before. But seriously, it’s the best way to test for CSS 3-D transform support. Use it.
Even with these difficulties mounting up, trying out 3-D transforms today is the right move. The CSS 3-D transforms module was developed by the same team at Apple that produced the CSS 2D Transforms and Animation modules. Both specifications have since been adopted by Mozilla and Opera. Transforming in three-dimensions now will guarantee you’ll be ahead of the game when the other browsers catch up.
The choice is yours. You can make excuses and pooh-pooh 3-D transforms because they’re too hard and only snobby Apple fans will see them today. Or, with a tip of the fedora to Mr Andy Clarke, you can get hard-boiled and start designing with the best features out there right this instant.
So, I bid you, in the words of the eternal Optimus Prime…
Transform and roll out.
Let’s get coding.
Perspective
To activate 3-D space, an element needs perspective. This can be applied in two ways: using the transform property, with the perspective as a functional notation:
-webkit-transform: perspective(600);
or using the perspective property:
-webkit-perspective: 600;
See example: Perspective 1.
The red element on the left uses transform: perspective() functional notation; the blue element on the right uses the perspective property
These two formats both trigger a 3-D space, but there is a difference. The first, functional notation is convenient for directly applying a 3-D transform on a single element (in the previous example, I use it in conjunction with a rotateY transform). But when used on multiple elements, the transformed elements don’t line up as expected. If you use the same transform across elements with different positions, each element will have its own vanishing point. To remedy this, use the perspective property on a parent element, so each child shares the same 3-D space.
See Example: Perspective 2.
Each red box on the left has its own vanishing point within the parent container; the blue boxes on the right share the vanishing point of the parent container
The value of perspective determines the intensity of the 3-D effect. Think of it as a distance from the viewer to the object. The greater the value, the further the distance, so the less intense the visual effect. perspective: 2000; yields a subtle 3-D effect, as if we were viewing an object from far away. perspective: 100; produces a tremendous 3-D effect, like a tiny insect viewing a massive object.
By default, the vanishing point for a 3-D space is positioned at its centre. You can change the position of the vanishing point with perspective-origin property.
-webkit-perspective-origin: 25% 75%;
See Example: Perspective 3.
3-D transform functions
As a web designer, you’re probably well acquainted with working in two dimensions, X and Y, positioning items horizontally and vertically. With a 3-D space initialised with perspective, we can now transform elements in all three glorious spatial dimensions, including the third Z dimension, depth.
3-D transforms use the same transform property used for 2-D transforms. If you’re familiar with 2-D transforms, you’ll find the basic 3D transform functions fairly similar.
rotateX(angle)
rotateY(angle)
rotateZ(angle)
translateZ(tz)
scaleZ(sz)
Whereas translateX() positions an element along the horizontal X-axis, translateZ() positions it along the Z-axis, which runs front to back in 3-D space. Positive values position the element closer to the viewer, negative values further away.
The rotate functions rotate the element around the corresponding axis. This is somewhat counter-intuitive at first, as you might imagine that rotateX will spin an object left to right. Instead, using rotateX(45deg) rotates an element around the horizontal X-axis, so the top of the element angles back and away, and the bottom gets closer to the viewer.
See Example: Transforms 1.
3-D rotate() and translate() functions around each axis
There are also several shorthand transform functions that require values for all three dimensions:
translate3d(tx,ty,tz)
scale3d(sx,sy,sz)
rotate3d(rx,ry,rz,angle)
Pro-tip: These foo3d() transform functions also have the benefit of triggering hardware acceleration in Safari. Dean Jackson, CSS 3-D transform spec author and main WebKit dude, writes (to Thomas Fuchs):
In essence, any transform that has a 3D operation as one of its functions will trigger hardware compositing, even when the actual transform is 2D, or not doing anything at all (such as translate3d(0,0,0)). Note this is just current behaviour, and could change in the future (which is why we don’t document or encourage it). But it is very helpful in some situations and can significantly improve redraw performance.
For the sake of simplicity, my demos will use the basic transform functions, but if you’re writing production-ready CSS for iOS or Safari-only, make sure to use the foo3d() functions to get the best rendering performance.
Card flip
We now have all the tools to start making 3-D objects. Let’s get started with something simple: flipping a card.
Here’s the basic markup we’ll need:
<section class="container">
<div id="card">
<figure class="front">1</figure>
<figure class="back">2</figure>
</div>
</section>
The .container will house the 3-D space. The #card acts as a wrapper for the 3-D object. Each face of the card has a separate element: .front; and .back. Even for such a simple object, I recommend using this same pattern for any 3-D transform. Keeping the 3-D space element and the object element(s) separate establishes a pattern that is simple to understand and easier to style.
We’re ready for some 3-D stylin’. First, apply the necessary perspective to the parent 3-D space, along with any size or positioning styles.
.container {
width: 200px;
height: 260px;
position: relative;
-webkit-perspective: 800;
}
Now the #card element can be transformed in its parent’s 3-D space. We’re combining absolute and relative positioning so the 3-D object is removed from the flow of the document. We’ll also add width: 100%; and height: 100%;. This ensures the object’s transform-origin will occur in the centre of .container. More on transform-origin later.
Let’s add a CSS3 transition so users can see the transform take effect.
#card {
width: 100%;
height: 100%;
position: absolute;
-webkit-transform-style: preserve-3d;
-webkit-transition: -webkit-transform 1s;
}
The .container’s perspective only applies to direct descendant children, in this case #card. In order for subsequent children to inherit a parent’s perspective, and live in the same 3-D space, the parent can pass along its perspective with transform-style: preserve-3d. Without 3-D transform-style, the faces of the card would be flattened with its parents and the back face’s rotation would be nullified.
To position the faces in 3-D space, we’ll need to reset their positions in 2-D with position: absolute. In order to hide the reverse sides of the faces when they are faced away from the viewer, we use backface-visibility: hidden.
#card figure {
display: block;
position: absolute;
width: 100%;
height: 100%;
-webkit-backface-visibility: hidden;
}
To flip the .back face, we add a basic 3-D transform of rotateY(180deg).
#card .front {
background: red;
}
#card .back {
background: blue;
-webkit-transform: rotateY(180deg);
}
With the faces in place, the #card requires a corresponding style for when it is flipped.
#card.flipped {
-webkit-transform: rotateY(180deg);
}
Now we have a working 3-D object. To flip the card, we can toggle the flipped class. When .flipped, the #card will rotate 180 degrees, thus exposing the .back face.
See Example: Card 1.
Flipping a card in three dimensions
Slide-flip
Take another look at the Weather App 3-D transition. You’ll notice that it’s not quite the same effect as our previous demo. If you follow the right edge of the card, you’ll find that its corners stay within the container. Instead of pivoting from the horizontal centre, it pivots on that right edge. But the transition is not just a rotation – the edge moves horizontally from right to left. We can reproduce this transition just by modifying a couple of lines of CSS from our original card flip demo.
The pivot point for the rotation occurs at the right side of the card. By default, the transform-origin of an element is at its horizontal and vertical centre (50% 50% or center center). Let’s change it to the right side:
#card { -webkit-transform-origin: right center; }
That flip now needs some horizontal movement with translateX. We’ll set the rotation to -180deg so it flips right side out.
#card.flipped {
-webkit-transform: translateX(-100%) rotateY(-180deg);
}
See Example: Card 2.
Creating a slide-flip from the right edge of the card
Cube
Creating 3-D card objects is a good way to get started with 3-D transforms. But once you’ve mastered them, you’ll be hungry to push it further and create some true 3-D objects: prisms. We’ll start out by making a cube.
The markup for the cube is similar to the card. This time, however, we need six child elements for all six faces of the cube:
<section class="container">
<div id="cube">
<figure class="front">1</figure>
<figure class="back">2</figure>
<figure class="right">3</figure>
<figure class="left">4</figure>
<figure class="top">5</figure>
<figure class="bottom">6</figure>
</div>
</section>
Basic position and size styles set the six faces on top of one another in the container.
.container {
width: 200px;
height: 200px;
position: relative;
-webkit-perspective: 1000;
}
#cube {
width: 100%;
height: 100%;
position: absolute;
-webkit-transform-style: preserve-3d;
}
#cube figure {
width: 196px;
height: 196px;
display: block;
position: absolute;
border: 2px solid black;
}
With the card, we only had to rotate its back face. The cube, however, requires that five of the six faces to be rotated. Faces 1 and 2 will be the front and back. Faces 3 and 4 will be the sides. Faces 5 and 6 will be the top and bottom.
#cube .front { -webkit-transform: rotateY(0deg); }
#cube .back { -webkit-transform: rotateX(180deg); }
#cube .right { -webkit-transform: rotateY(90deg); }
#cube .left { -webkit-transform: rotateY(-90deg); }
#cube .top { -webkit-transform: rotateX(90deg); }
#cube .bottom { -webkit-transform: rotateX(-90deg); }
We could remove the first #cube .front style declaration, as this transform has no effect, but let’s leave it in to keep our code consistent.
Now each face is rotated, and only the front face is visible. The four side faces are all perpendicular to the viewer, so they appear invisible. To push them out to their appropriate sides, they need to be translated out from the centre of their positions. Each side of the cube is 200 pixels wide. From the cube’s centre they’ll need to be translated out half that distance, 100px.
#cube .front { -webkit-transform: rotateY(0deg) translateZ(100px); }
#cube .back { -webkit-transform: rotateX(180deg) translateZ(100px); }
#cube .right { -webkit-transform: rotateY(90deg) translateZ(100px); }
#cube .left { -webkit-transform: rotateY(-90deg) translateZ(100px); }
#cube .top { -webkit-transform: rotateX(90deg) translateZ(100px); }
#cube .bottom { -webkit-transform: rotateX(-90deg) translateZ(100px); }
Note here that the translateZ function comes after the rotate. The order of transform functions is important. Take a moment and soak this up. Each face is first rotated towards its position, then translated outward in a separate vector.
We have a working cube, but we’re not done yet.
Returning to the Z-axis origin
For the sake of our users, our 3-D transforms should not distort the interface when the active panel is at its resting position. But once we start pushing elements off their Z-axis origin, distortion is inevitable.
In order to keep 3-D transforms snappy, Safari composites the element, then applies the transform. Consequently, anti-aliasing on text will remain whatever it was before the transform was applied. When transformed forward in 3-D space, significant pixelation can occur.
See Example: Transforms 2.
Looking back at the Perspective 3 demo, note that no matter how small the perspective value is, or wherever the transform-origin may be, the panel number 1 always returns to its original position, as if all those funky 3-D transforms didn’t even matter.
To resolve the distortion and restore pixel perfection to our #cube, we can push the 3-D object back, so that the front face will be positioned back to the Z-axis origin.
#cube { -webkit-transform: translateZ(-100px); }
See Example: Cube 1.
Restoring the front face to the original position on the Z-axis
Rotating the cube
To expose any face of the cube, we’ll need a style that rotates the cube to expose any face. The transform values are the opposite of those for the corresponding face. We toggle the necessary class on the #box to apply the appropriate transform.
#cube.show-front { -webkit-transform: translateZ(-100px) rotateY(0deg); }
#cube.show-back { -webkit-transform: translateZ(-100px) rotateX(-180deg); }
#cube.show-right { -webkit-transform: translateZ(-100px) rotateY(-90deg); }
#cube.show-left { -webkit-transform: translateZ(-100px) rotateY(90deg); }
#cube.show-top { -webkit-transform: translateZ(-100px) rotateX(-90deg); }
#cube.show-bottom { -webkit-transform: translateZ(-100px) rotateX(90deg); }
Notice how the order of the transform functions has reversed. First, we push the object back with translateZ, then we rotate it.
Finishing up, we can add a transition to animate the rotation between states.
#cube { -webkit-transition: -webkit-transform 1s; }
See Example: Cube 2.
Rotating the cube with a CSS transition
Rectangular prism
Cubes are easy enough to generate, as we only have to worry about one measurement. But how would we handle a non-regular rectangular prism? Let’s try to make one that’s 300 pixels wide, 200 pixels high, and 100 pixels deep.
The markup remains the same as the #cube, but we’ll switch the cube id for #box. The container styles remain mostly the same:
.container {
width: 300px;
height: 200px;
position: relative;
-webkit-perspective: 1000;
}
#box {
width: 100%;
height: 100%;
position: absolute;
-webkit-transform-style: preserve-3d;
}
Now to position the faces. Each set of faces will need their own sizes. The smaller faces (left, right, top and bottom) need to be positioned in the centre of the container, where they can be easily rotated and then shifted outward. The thinner left and right faces get positioned left: 100px ((300 − 100) ÷ 2), The stouter top and bottom faces get positioned top: 50px ((200 − 100) ÷ 2).
#box figure {
display: block;
position: absolute;
border: 2px solid black;
}
#box .front,
#box .back {
width: 296px;
height: 196px;
}
#box .right,
#box .left {
width: 96px;
height: 196px;
left: 100px;
}
#box .top,
#box .bottom {
width: 296px;
height: 96px;
top: 50px;
}
The rotate values can all remain the same as the cube example, but for this rectangular prism, the translate values do differ. The front and back faces are each shifted out 50 pixels since the #box is 100 pixels deep. The translate value for the left and right faces is 150 pixels for their 300 pixels width. Top and bottom panels take 100 pixels for their 200 pixels height:
#box .front { -webkit-transform: rotateY(0deg) translateZ(50px); }
#box .back { -webkit-transform: rotateX(180deg) translateZ(50px); }
#box .right { -webkit-transform: rotateY(90deg) translateZ(150px); }
#box .left { -webkit-transform: rotateY(-90deg) translateZ(150px); }
#box .top { -webkit-transform: rotateX(90deg) translateZ(100px); }
#box .bottom { -webkit-transform: rotateX(-90deg) translateZ(100px); }
See Example: Box 1.
Just like the cube example, to expose a face, the #box needs to have a style to reverse that face’s transform. Both the translateZ and rotate values are the opposites of the corresponding face.
#box.show-front { -webkit-transform: translateZ(-50px) rotateY(0deg); }
#box.show-back { -webkit-transform: translateZ(-50px) rotateX(-180deg); }
#box.show-right { -webkit-transform: translateZ(-150px) rotateY(-90deg); }
#box.show-left { -webkit-transform: translateZ(-150px) rotateY(90deg); }
#box.show-top { -webkit-transform: translateZ(-100px) rotateX(-90deg); }
#box.show-bottom { -webkit-transform: translateZ(-100px) rotateX(90deg); }
See Example: Box 2.
Rotating the rectangular box with a CSS transition
Carousel
Front-end developers have a myriad of choices when it comes to content carousels. Now that we have 3-D capabilities in our browsers, why not take a shot at creating an actual 3-D carousel?
The markup for this demo takes the same form as the box, cube and card. Let’s make it interesting and have a carousel with nine panels.
<div class="container">
<div id="carousel">
<figure>1</figure>
<figure>2</figure>
<figure>3</figure>
<figure>4</figure>
<figure>5</figure>
<figure>6</figure>
<figure>7</figure>
<figure>8</figure>
<figure>9</figure>
</div>
</div>
Now, apply basic layout styles. Let’s give each panel of the #carousel 20 pixel gaps between one another, done here with left: 10px; and top: 10px;. The effective width of each panel is 210 pixels.
.container {
width: 210px;
height: 140px;
position: relative;
-webkit-perspective: 1000;
}
#carousel {
width: 100%;
height: 100%;
position: absolute;
-webkit-transform-style: preserve-3d;
}
#carousel figure {
display: block;
position: absolute;
width: 186px;
height: 116px;
left: 10px;
top: 10px;
border: 2px solid black;
}
Next up: rotating the faces. This #carousel has nine panels. If each panel gets an equal distribution on the carousel, each panel would be rotated forty degrees from its neighbour (360 ÷ 9).
#carousel figure:nth-child(1) { -webkit-transform: rotateY(0deg); }
#carousel figure:nth-child(2) { -webkit-transform: rotateY(40deg); }
#carousel figure:nth-child(3) { -webkit-transform: rotateY(80deg); }
#carousel figure:nth-child(4) { -webkit-transform: rotateY(120deg); }
#carousel figure:nth-child(5) { -webkit-transform: rotateY(160deg); }
#carousel figure:nth-child(6) { -webkit-transform: rotateY(200deg); }
#carousel figure:nth-child(7) { -webkit-transform: rotateY(240deg); }
#carousel figure:nth-child(8) { -webkit-transform: rotateY(280deg); }
#carousel figure:nth-child(9) { -webkit-transform: rotateY(320deg); }
Now, the outward shift. Back when we were creating the cube and box, the translate value was simple to calculate, as it was equal to one half the width, height or depth of the object. With this carousel, there is no size we can automatically use as a reference. We’ll have to calculate the distance of the shift by other means.
Drawing a diagram of the carousel, we can see that we know only two things: the width of each panel is 210 pixels; and the each panel is rotated forty degrees from the next. If we split one of these segments down its centre, we get a right-angled triangle, perfect for some trigonometry.
We can determine the length of r in this diagram with a basic tangent equation:
There you have it: the panels need to be translated 288 pixels in 3-D space.
#carousel figure:nth-child(1) { -webkit-transform: rotateY(0deg) translateZ(288px); }
#carousel figure:nth-child(2) { -webkit-transform: rotateY(40deg) translateZ(288px); }
#carousel figure:nth-child(3) { -webkit-transform: rotateY(80deg) translateZ(288px); }
#carousel figure:nth-child(4) { -webkit-transform: rotateY(120deg) translateZ(288px); }
#carousel figure:nth-child(5) { -webkit-transform: rotateY(160deg) translateZ(288px); }
#carousel figure:nth-child(6) { -webkit-transform: rotateY(200deg) translateZ(288px); }
#carousel figure:nth-child(7) { -webkit-transform: rotateY(240deg) translateZ(288px); }
#carousel figure:nth-child(8) { -webkit-transform: rotateY(280deg) translateZ(288px); }
#carousel figure:nth-child(9) { -webkit-transform: rotateY(320deg) translateZ(288px); }
If we decide to change the width of the panel or the number of panels, we only need to plug in those two variables into our equation to get the appropriate translateZ value. In JavaScript terms, that equation would be:
var tz = Math.round( ( panelSize / 2 ) /
Math.tan( ( ( Math.PI * 2 ) / numberOfPanels ) / 2 ) );
// or simplified to
var tz = Math.round( ( panelSize / 2 ) /
Math.tan( Math.PI / numberOfPanels ) );
Just like our previous 3-D objects, to show any one panel we need only apply the reverse transform on the carousel. Here’s the style to show the fifth panel:
-webkit-transform: translateZ(-288px) rotateY(-160deg);
See Example: Carousel 1.
By now, you probably have two thoughts:
Rewriting transform styles for each panel looks tedious.
Why bother doing high school maths? Aren’t robots supposed to be doing all this work for us?
And you’re absolutely right. The repetitive nature of 3-D objects lends itself to scripting. We can offload all the monotonous transform styles to our dynamic script, which, if done correctly, will be more flexible than the hard-coded version.
See Example: Carousel 2.
Conclusion
3-D transforms change the way we think about the blank canvas of web design. Better yet, they change the canvas itself, trading in the flat surface for voluminous depth.
My hope is that you took at least one peak at a demo and were intrigued. We web designers, who have rejoiced for border-radius, box-shadow and background gradients, now have an incredible tool at our disposal in 3-D transforms. They deserve just the same enthusiasm, research and experimentation we have seen on other CSS3 features. Now is the perfect time to take the plunge and start thinking about how to use three dimensions to elevate our craft. I’m breathless waiting for what’s to come.
See you on the flip side. |
2010 |
David DeSandro |
daviddesandro |
2010-12-14T00:00:00+00:00 |
https://24ways.org/2010/intro-to-css-3d-transforms/ |
code |
| 211 |
Automating Your Accessibility Tests |
Accessibility is one of those things we all wish we were better at. It can lead to a bunch of questions like: how do we make our site better? How do we test what we have done? Should we spend time each day going through our site to check everything by hand? Or just hope that everyone on our team has remembered to check their changes are accessible?
This is where automated accessibility tests can come in. We can set up automated tests and have them run whenever someone makes a pull request, and even alongside end-to-end tests, too.
Automated tests can’t cover everything however; only 20 to 50% of accessibility issues can be detected automatically. For example, we can’t yet automate the comparison of an alt attribute with an image’s content, and there are some screen reader tests that need to be carried out by hand too. To ensure our site is as accessible as possible, we will still need to carry out manual tests, and I will cover these later.
First, I’m going to explain how I implemented automated accessibility tests on Elsevier’s ecommerce pages, and share some of the lessons I learnt along the way.
Picking the right tool
One of the hardest, but most important parts of creating our automated accessibility tests was choosing the right tool.
We began by investigating aXe CLI, but soon realised it wouldn’t fit our requirements. It couldn’t check pages that required a visitor to log in, so while we could test our product pages, we couldn’t test any customer account pages. Instead we moved over to Pa11y. Its beforeScript step meant we could log into the site and test pages such as the order history.
The example below shows the how the beforeScript step completes a login form and then waits for the login to complete before testing the page:
beforeScript: function(page, options, next) {
// An example function that can be used to make sure changes have been confirmed before continuing to run Pa11y
function waitUntil(condition, retries, waitOver) {
page.evaluate(condition, function(err, result) {
if (result || retries < 1) {
// Once the changes have taken place continue with Pa11y testing
waitOver();
} else {
retries -= 1;
setTimeout(function() {
waitUntil(condition, retries, waitOver);
}, 200);
}
});
}
// The script to manipulate the page must be run with page.evaluate to be run within the context of the page
page.evaluate(function() {
const user = document.querySelector('#login-form input[name="email"]');
const password = document.querySelector('#login-form input[name="password"]');
const submit = document.querySelector('#login-form input[name="submit"]');
user.value = 'user@example.com';
password.value = 'password';
submit.click();
}, function() {
// Use the waitUntil function to set the condition, number of retries and the callback
waitUntil(function() {
return window.location.href === 'https://example.com';
}, 20, next);
});
}
The waitUntil callback allows the test to be delayed until our test user is successfully logged in.
Another thing to consider when picking a tool is the type of error messages it produces. aXe groups all elements with the same error together, so the list of issues is a lot easier to read, and it’s easier to identify the most commons problems. For example, here are some elements that have insufficient colour contrast:
Violation of "color-contrast" with 8 occurrences!
Ensures the contrast between foreground and background colors meets
WCAG 2 AA contrast ratio thresholds. Correct invalid elements at:
- #maincontent > .make_your_mark > div:nth-child(2) > p > span > span
- #maincontent > .make_your_mark > div:nth-child(4) > p > span > span
- #maincontent > .inform_your_decisions > div:nth-child(2) > p > span > span
- #maincontent > .inform_your_decisions > div:nth-child(4) > p > span > span
- #maincontent > .inform_your_decisions > div:nth-child(6) > p > span > span
- #maincontent > .inform_your_decisions > div:nth-child(8) > p > span > span
- #maincontent > .inform_your_decisions > div:nth-child(10) > p > span > span
- #maincontent > .inform_your_decisions > div:nth-child(12) > p > span > span
For details, see: https://dequeuniversity.com/rules/axe/2.5/color-contrast
aXe also provides links to their site where they discuss the best way to fix the problem.
In comparison, Pa11y lists each individual error which can lead to a very verbose list. However, it does provide helpful suggestions of how to fix problems, such as suggesting an alternative shade of a colour to use:
• Error: This element has insufficient contrast at this conformance level.
Expected a contrast ratio of at least 4.5:1, but text in this element has a contrast ratio of 2.96:1.
Recommendation: change text colour to #767676.
⎣ WCAG2AA.Principle1.Guideline1_4.1_4_3.G18.Fail
⎣ #maincontent > div:nth-child(10) > div:nth-child(8) > p > span > span
⎣ <span style="color:#969696">Featured products:</span>
Integrating into our build pipeline
We decided the perfect time to run our accessibility tests would be alongside our end-to-end tests. We have a Jenkins job that detects changes to our staging site and then triggers the end-to-end tests, and in turn our accessibility tests. Our Jenkins job retrieves the contents of a GitHub repository containing our Pa11y script file and npm package manifest.
Once Jenkins has cloned the repository, it installs any dependencies and executes the tests via:
npm install && npm test
Bundling the URLs to be tested into our test script means we don’t have a command line style test where we list each URL we wish to test in the Jenkins CLI. It’s an effective method but can also be cluttered, and obscure which URLs are being tested.
In the middle of the office we have a monitor displaying a Jenkins dashboard and from this we can see if the accessibility tests are passing or failing. Everyone in the team has access to the Jenkins logs and when the build fails they can see why and fix the issue.
Fixing the issues
As mentioned earlier, Pa11y can generate a long list of areas for improvement which can be very verbose and quite overwhelming. I recommend going through the list to see which issues occur most frequently and fix those first. For example, we initially had a lot of errors around colour contrast, and one shade of grey in particular. By making this colour darker, the number of errors decreased, and we could focus on the remaining issues.
Another thing I like to do is to tackle the quick fixes, such as adding alt text to images. These are small things that allow us to make an impact instantly, giving us time to fix more detailed concerns such as addressing tabindex issues, or speaking to our designers about changing the contrast of elements on the site.
Manual testing
Adding automated tests to check our site for accessibility is great, but as I mentioned earlier, this can only cover 20-50% of potential issues. To improve on this, we need to test by hand too, either by ourselves or by asking others.
One way we can test our site is to throw our mouse or trackpad away and interact with the site using only a keyboard. This allows us to check items such as tab order, and ensure menu items, buttons etc. can be used without a mouse. The commands may be different on different operating systems, but there are some great guides online for learning more about these.
It’s tempting to add alt text and aria-labels to make errors go away, but if they don’t make any sense, what use are they really? Using a screenreader we can check that alt text accurately represents the image. This is also a great way to double check that our ARIA roles make sense, and that they correctly identify elements and how to interact with them. When testing our site with screen readers, it’s important to remember that not all screen readers are the same and some may interact with our site differently to others.
Consider asking a range of people with different needs and abilities to test your site, too. People experience the web in numerous ways, be they permanent, temporary or even situational. They may interact with your site in ways you hadn’t even thought about, so this is a good way to broaden your knowledge and awareness.
Tips and tricks
One of our main issues with Pa11y is that it may find issues we don’t have the power to solve. A perfect example of this is the one pixel image Facebook injects into our site. So, we wrote a small function to go though such errors and ignore the ones that we cannot fix.
const test = pa11y({
....
hideElements: '#ratings, #js-bigsearch',
...
});
const ignoreErrors: string[] = [
'<img src="https://books.google.com/intl/en/googlebooks/images/gbs_preview_button1.gif" border="0" style="cursor: pointer;" class="lightbox-is-image">',
'<script type="text/javascript" id="">var USI_orderID=google_tag_mana...</script>',
'<img height="1" width="1" style="display:none" src="https://www.facebook.com/tr?id=123456789012345&ev=PageView&noscript=1">'
];
const filterResult = result => {
if (ignoreErrors.indexOf(result.context) > -1) {
return false;
}
return true;
};
Initially we wanted to focus on fixing the major problems, so we added a rule to ignore notices and warnings. This made the list or errors much smaller and allowed us focus on fixing major issues such as colour contrast and missing alt text. The ignored notices and warnings can be added in later after these larger issues have been resolved.
const test = pa11y({
ignore: [
'notice',
'warning'
],
...
});
Jenkins gotchas
While using Jenkins we encountered a few problems. Sometimes Jenkins would indicate a build had passed when in reality it had failed. This was because Pa11y had timed out due to PhantomJS throwing an error, or the test didn’t go past the first URL. Pa11y has recently released a new beta version that uses headless Chrome instead of PhantomJS, so hopefully these issues will less occur less often.
We tried a few approaches to solve these issues. First we added error handling, iterating over the array of test URLs so that if an unexpected error happened, we could catch it and exit the process with an error indicating that the job had failed (using process.exit(1)).
for (const url of urls) {
try {
console.log(url);
let urlResult = await run(url);
urlResult = urlResult.filter(filterResult);
urlResult.forEach(result => console.log(result));
}
catch (e) {
console.log('Error:', e);
process.exit(1);
}
}
We also had issues with unhandled rejections sometimes caused by a session disconnecting or similar errors. To avoid Jenkins indicating our site was passing with 100% accessibility, when in reality it had not executed any tests, we instructed Jenkins to fail the job when an unhandled rejection or uncaught exception occurred:
process.on('unhandledRejection', (reason, p) => {
console.log('Unhandled Rejection at:', p, 'reason:', reason);
process.exit(1);
});
process.on('uncaughtException', (err) => {
console.log('Caught exception: ${err}n');
process.exit(1);
});
Now it’s your turn
That’s it! That’s how we automated accessibility testing for Elsevier ecommerce pages, allowing us to improve our site and make it more accessible for everyone. I hope our experience can help you automate accessibility tests on your own site, and bring the web a step closer to being accessible to all. |
2017 |
Seren Davies |
serendavies |
2017-12-07T00:00:00+00:00 |
https://24ways.org/2017/automating-your-accessibility-tests/ |
code |
| 182 |
Breaking Out The Edges of The Browser |
HTML5 contains more than just the new entities for a more meaningful document, it also contains an arsenal of JavaScript APIs. So many in fact, that some APIs have outgrown the HTML5 spec’s backyard and have been sent away to grow up all on their own and been given the prestigious honour of being specs in their own right.
So when I refer to (bendy finger quote) “HTML5”, I mean the HTML5 specification and a handful of other specifications that help us authors build web applications.
Examples of those specs I would include in the umbrella term would be: geolocation, web storage, web databases, web sockets and web workers, to name a few.
For all you guys and gals, on this special 2009 series of 24 ways, I’m just going to focus on data storage and offline applications: boldly taking your browser where no browser has gone before!
Web Storage
The Web Storage API is basically cookies on steroids, a unhealthy dosage of steroids. Cookies are always a pain to work with. First of all you have the problem of setting, changing and deleting them. Typically solved by Googling and blindly relying on PPK’s solution. If that wasn’t enough, there’s the 4Kb limit that some of you have hit when you really don’t want to.
The Web Storage API gets around all of the hoops you have to jump through with cookies. Storage supports around 5Mb of data per domain (the spec’s recommendation, but it’s open to the browsers to implement anything they like) and splits in to two types of storage objects:
sessionStorage – available to all pages on that domain while the window remains open
localStorage – available on the domain until manually removed
Support
Ignoring beta browsers for our support list, below is a list of the major browsers and their support for the Web Storage API:
Latest: Internet Explorer, Firefox, Safari (desktop & mobile/iPhone)
Partial: Google Chrome (only supports localStorage)
Not supported: Opera (as of 10.10)
Usage
Both sessionStorage and localStorage support the same interface for accessing their contents, so for these examples I’ll use localStorage.
The storage interface includes the following methods:
setItem(key, value)
getItem(key)
key(index)
removeItem(key)
clear()
In the simple example below, we’ll use setItem and getItem to store and retrieve data:
localStorage.setItem('name', 'Remy');
alert( localStorage.getItem('name') );
Using alert boxes can be a pretty lame way of debugging. Conveniently Safari (and Chrome) include database tab in their debugging tools (cmd+alt+i), so you can get a visual handle on the state of your data:
Viewing localStorage
As far as I know only Safari has this view on stored data natively in the browser. There may be a Firefox plugin (but I’ve not found it yet!) and IE… well that’s just IE.
Even though we’ve used setItem and getItem, there’s also a few other ways you can set and access the data.
In the example below, we’re accessing the stored value directly using an expando and equally, you can also set values this way:
localStorage.name = "Remy";
alert( localStorage.name ); // shows "Remy"
The Web Storage API also has a key method, which is zero based, and returns the key in which data has been stored. This should also be in the same order that you set the keys, for example:
alert( localStorage.getItem(localStorage.key(0)) );
// shows "Remy"
I mention the key() method because it’s not an unlikely name for a stored value. This can cause serious problems though.
When selecting the names for your keys, you need to be sure you don’t take one of the method names that are already on the storage object, like key, clear, etc. As there are no warnings when you try to overwrite the methods, it means when you come to access the key() method, the call breaks as key is a string value and not a function.
You can try this yourself by creating a new stored value using localStorage.key = "foo" and you’ll see that the Safari debugger breaks because it relies on the key() method to enumerate each of the stored values.
Usage Notes
Currently all browsers only support storing strings. This also means if you store a numeric, it will get converted to a string:
localStorage.setItem('count', 31);
alert(typeof localStorage.getItem('count'));
// shows "string"
This also means you can’t store more complicated objects natively with the storage objects. To get around this, you can use Douglas Crockford’s JSON parser (though Firefox 3.5 has JSON parsing support baked in to the browser – yay!) json2.js to convert the object to a stringified JSON object:
var person = {
name: 'Remy',
height: 'short',
location: 'Brighton, UK'
};
localStorage.setItem('person', JSON.stringify(person));
alert( JSON.parse(localStorage.getItem('person')).name );
// shows "Remy"
Alternatives
There are a few solutions out there that provide storage solutions that detect the Web Storage API, and if it’s not available, fall back to different technologies (for instance, using a flash object to store data). One comprehensive version of this is Dojo’s storage library. I’m personally more of a fan of libraries that plug missing functionality under the same namespace, just as Crockford’s JSON parser does (above).
For those interested it what that might look like, I’ve mocked together a simple implementation of sessionStorage. Note that it’s incomplete (because it’s missing the key method), and it could be refactored to not using the JSON stringify (but you would need to ensure that the values were properly and safely encoded):
// requires json2.js for all browsers other than Firefox 3.5
if (!window.sessionStorage && JSON) {
window.sessionStorage = (function () {
// window.top.name ensures top level, and supports around 2Mb
var data = window.top.name ? JSON.parse(window.top.name) : {};
return {
setItem: function (key, value) {
data[key] = value+""; // force to string
window.top.name = JSON.stringify(data);
},
removeItem: function (key) {
delete data[key];
window.top.name = JSON.stringify(data);
},
getItem: function (key) {
return data[key] || null;
},
clear: function () {
data = {};
window.top.name = '';
}
};
})();
}
Now that we’ve cracked the cookie jar with our oversized Web Storage API, let’s have a look at how we take our applications offline entirely.
Offline Applications
Offline applications is (still) part of the HTML5 specification. It allows developers to build a web app and have it still function without an internet connection. The app is access via the same URL as it would be if the user were online, but the contents (or what the developer specifies) is served up to the browser from a local cache. From there it’s just an everyday stroll through open web technologies, i.e. you still have access to the Web Storage API and anything else you can do without a web connection.
For this section, I’ll refer you to a prototype demo I wrote recently of a contrived Rubik’s cube (contrived because it doesn’t work and it only works in Safari because I’m using 3D transforms).
Offline Rubik’s cube
Support
Support for offline applications is still fairly limited, but the possibilities of offline applications is pretty exciting, particularly as we’re seeing mobile support and support in applications such as Fluid (and I would expect other render engine wrapping apps).
Support currently, is as follows:
Latest: Safari (desktop & mobile/iPhone)
Sort of: Firefox‡
Not supported: Internet Explorer, Opera, Google Chrome
‡ Firefox 3.5 was released to include offline support, but in fact has bugs where it doesn’t work properly (certainly on the Mac), Minefield (Firefox beta) has resolved the bug.
Usage
The status of the application’s cache can be tested from the window.applicationCache object. However, we’ll first look at how to enable your app for offline access.
You need to create a manifest file, which will tell the browser what to cache, and then we point our web page to that cache:
<!DOCTYPE html>
<html manifest="remy.manifest">
<!-- continues ... -->
For the manifest to be properly read by the browser, your server needs to serve the .manifest files as text/manifest by adding the following to your mime.types:
text/cache-manifest manifest
Next we need to populate our manifest file so the browser can read it:
CACHE MANIFEST
/demo/rubiks/index.html
/demo/rubiks/style.css
/demo/rubiks/jquery.min.js
/demo/rubiks/rubiks.js
# version 15
The first line of the manifest must read CACHE MANIFEST. Then subsequent lines tell the browser what to cache.
The HTML5 spec recommends that you include the calling web page (in my case index.html), but it’s not required. If I didn’t include index.html, the browser would cache it as part of the offline resources.
These resources are implicitly under the CACHE namespace (which you can specify any number of times if you want to).
In addition, there are two further namespaces: NETWORK and FALLBACK.
NETWORK is a whitelist namespace that tells the browser not to cache this resource and always try to request it through the network.
FALLBACK tells the browser that whilst in offline mode, if the resource isn’t available, it should return the fallback resource.
Finally, in my example I’ve included a comment with a version number. This is because once you include a manifest, the only way you can tell the browser to reload the resources is if the manifest contents changes. So I’ve included a version number in the manifest which I can change forcing the browser to reload all of the assets.
How it works
If you’re building an app that makes use of the offline cache, I would strongly recommend that you add the manifest last. The browser implementations are very new, so can sometimes get a bit tricky to debug since once the resources are cached, they really stick in the browser.
These are the steps that happen during a request for an app with a manifest:
Browser: sends request for your app.html
Server: serves all associated resources with app.html – as normal
Browser: notices that app.html has a manifest, it re-request the assets in the manifest
Server: serves the requested manifest assets (again)
Browser: window.applicationCache has a status of UPDATEREADY
Browser: reloads
Browser: only request manifest file (which doesn’t show on the net requests panel)
Server: responds with 304 Not Modified on the manifest file
Browser: serves all the cached resources locally
What might also add confusion to this process, is that the way the browsers work (currently) is if there is a cache already in place, it will use this first over updated resources. So if your manifest has changed, the browser will have already loaded the offline cache, so the user will only see the updated on the next reload.
This may seem a bit convoluted, but you can also trigger some of this manually through the applicationCache methods which can ease some of this pain.
If you bind to the online event you can manually try to update the offline cache. If the cache has then updated, swap the updated resources in to the cache and the next time the app loads it will be up to date. You could also prompt your user to reload the app (which is just a refresh) if there’s an update available.
For example (though this is just pseudo code):
addEvent(applicationCache, 'updateready', function () {
applicationCache.swapCache();
tellUserToRefresh();
});
addEvent(window, 'online', function () {
applicationCache.update();
});
Breaking out of the Browser
So that’s two different technologies that you can use to break out of the traditional browser/web page model and get your apps working in a more application-ny way.
There’s loads more in the HTML5 and non-HTML5 APIs to play with, so take your Christmas break to check them out! |
2009 |
Remy Sharp |
remysharp |
2009-12-02T00:00:00+00:00 |
https://24ways.org/2009/breaking-out-the-edges-of-the-browser/ |
code |
| 223 |
Calculating Color Contrast |
Some websites and services allow you to customize your profile by uploading pictures, changing the background color or other aspects of the design. As a customer, this personalization turns a web app into your little nest where you store your data. As a designer, letting your customers have free rein over the layout and design is a scary prospect. So what happens to all the stock text and images that are designed to work on nice white backgrounds? Even the Mac only lets you choose between two colors for the OS, blue or graphite! Opening up the ability to customize your site’s color scheme can be a recipe for disaster unless you are flexible and understand how to find maximum color contrasts.
In this article I will walk you through two simple equations to determine if you should be using white or black text depending on the color of the background. The equations are both easy to implement and produce similar results. It isn’t a matter of which is better, but more the fact that you are using one at all! That way, even with the craziest of Geocities color schemes that your customers choose, at least your text will still be readable.
Let’s have a look at a range of various possible colors. Maybe these are pre-made color schemes, corporate colors, or plucked from an image.
Now that we have these potential background colors and their hex values, we need to find out whether the corresponding text should be in white or black, based on which has a higher contrast, therefore affording the best readability. This can be done at runtime with JavaScript or in the back-end before the HTML is served up.
There are two functions I want to compare. The first, I call ’50%’. It takes the hex value and compares it to the value halfway between pure black and pure white. If the hex value is less than half, meaning it is on the darker side of the spectrum, it returns white as the text color. If the result is greater than half, it’s on the lighter side of the spectrum and returns black as the text value.
In PHP:
function getContrast50($hexcolor){
return (hexdec($hexcolor) > 0xffffff/2) ? 'black':'white';
}
In JavaScript:
function getContrast50(hexcolor){
return (parseInt(hexcolor, 16) > 0xffffff/2) ? 'black':'white';
}
It doesn’t get much simpler than that! The function converts the six-character hex color into an integer and compares that to one half the integer value of pure white. The function is easy to remember, but is naive when it comes to understanding how we perceive parts of the spectrum. Different wavelengths have greater or lesser impact on the contrast.
The second equation is called ‘YIQ’ because it converts the RGB color space into YIQ, which takes into account the different impacts of its constituent parts. Again, the equation returns white or black and it’s also very easy to implement.
In PHP:
function getContrastYIQ($hexcolor){
$r = hexdec(substr($hexcolor,0,2));
$g = hexdec(substr($hexcolor,2,2));
$b = hexdec(substr($hexcolor,4,2));
$yiq = (($r*299)+($g*587)+($b*114))/1000;
return ($yiq >= 128) ? 'black' : 'white';
}
In JavaScript:
function getContrastYIQ(hexcolor){
var r = parseInt(hexcolor.substr(0,2),16);
var g = parseInt(hexcolor.substr(2,2),16);
var b = parseInt(hexcolor.substr(4,2),16);
var yiq = ((r*299)+(g*587)+(b*114))/1000;
return (yiq >= 128) ? 'black' : 'white';
}
You’ll notice first that we have broken down the hex value into separate RGB values. This is important because each of these channels is scaled in accordance to its visual impact. Once everything is scaled and normalized, it will be in a range between zero and 255. Much like the previous ’50%’ function, we now need to check if the input is above or below halfway. Depending on where that value is, we’ll return the corresponding highest contrasting color.
That’s it: two simple contrast equations which work really well to determine the best readability.
If you are interested in learning more, the W3C has a few documents about color contrast and how to determine if there is enough contrast between any two colors. This is important for accessibility to make sure there is enough contrast between your text and link colors and the background.
There is also a great article by Kevin Hale on Particletree about his experience with choosing light or dark themes. To round it out, Jonathan Snook created a color contrast picker which allows you to play with RGB sliders to get values for YIQ, contrast and others. That way you can quickly fiddle with the knobs to find the right balance.
Comparing results
Let’s revisit our color schemes and see which text color is recommended for maximum contrast based on these two equations.
If we use the simple ’50%’ contrast function, we can see that it recommends black against all the colors except the dark green and purple on the second row. In general, the equation feels the colors are light and that black is a better choice for the text.
The more complex ‘YIQ’ function, with its weighted colors, has slightly different suggestions. White text is still recommended for the very dark colors, but there are some surprises. The red and pink values show white text rather than black. This equation takes into account the weight of the red value and determines that the hue is dark enough for white text to show the most contrast.
As you can see, the two contrast algorithms agree most of the time. There are some instances where they conflict, but overall you can use the equation that you prefer. I don’t think it is a major issue if some edge-case colors get one contrast over another, they are still very readable.
Now let’s look at some common colors and then see how the two functions compare. You can quickly see that they do pretty well across the whole spectrum.
In the first few shades of grey, the white and black contrasts make sense, but as we test other colors in the spectrum, we do get some unexpected deviation. Pure red #FF0000 has a flip-flop. This is due to how the ‘YIQ’ function weights the RGB parts. While you might have a personal preference for one style over another, both are justifiable.
In this second round of colors, we go deeper into the spectrum, off the beaten track. Again, most of the time the contrasting algorithms are in sync, but every once in a while they disagree. You can select which you prefer, neither of which is unreadable.
Conclusion
Contrast in color is important, especially if you cede all control and take a hands-off approach to the design. It is important to select smart defaults by making the contrast between colors as high as possible. This makes it easier for your customers to read, increases accessibility and is generally just easier on the eyes.
Sure, there are plenty of other equations out there to determine contrast; what is most important is that you pick one and implement it into your system.
So, go ahead and experiment with color in your design. You now know how easy it is to guarantee that your text will be the most readable in any circumstance. |
2010 |
Brian Suda |
briansuda |
2010-12-24T00:00:00+00:00 |
https://24ways.org/2010/calculating-color-contrast/ |
code |
| 147 |
Christmas Is In The AIR |
That’s right, Christmas is coming up fast and there’s plenty of things to do. Get the tree and lights up, get the turkey, buy presents and who know what else. And what about Santa? He’s got a list. I’m pretty sure he’s checking it twice.
Sure, we could use an existing list making web site or even a desktop widget. But we’re geeks! What’s the fun in that? Let’s build our own to-do list application and do it with Adobe AIR!
What’s Adobe AIR?
Adobe AIR, formerly codenamed Apollo, is a runtime environment that runs on both Windows and OSX (with Linux support to follow). This runtime environment lets you build desktop applications using Adobe technologies like Flash and Flex. Oh, and HTML. That’s right, you web standards lovin’ maniac. You can build desktop applications that can run cross-platform using the trio of technologies, HTML, CSS and JavaScript.
If you’ve tried developing with AIR before, you’ll need to get re-familiarized with the latest beta release as many things have changed since the last one (such as the API and restrictions within the sandbox.)
To get started
To get started in building an AIR application, you’ll need two basic things:
The AIR runtime. The runtime is needed to run any AIR-based application.
The SDK. The software development kit gives you all the pieces to test your application. Unzip the SDK into any folder you wish.
You’ll also want to get your hands on the JavaScript API documentation which you’ll no doubt find yourself getting into before too long. (You can download it, too.)
Also of interest, some development environments have support for AIR built right in. Aptana doesn’t have support for beta 3 yet but I suspect it’ll be available shortly.
Within the SDK, there are two main tools that we’ll use: one to test the application (ADL) and another to build a distributable package of our application (ADT). I’ll get into this some more when we get to that stage of development.
Building our To-do list application
The first step to building an application within AIR is to create an XML file that defines our default application settings. I call mine application.xml, mostly because Aptana does that by default when creating a new AIR project. It makes sense though and I’ve stuck with it. Included in the templates folder of the SDK is an example XML file that you can use.
The first key part to this after specifying things like the application ID, version, and filename, is to specify what the default content should be within the content tags. Enter in the name of the HTML file you wish to load. Within this HTML file will be our application.
<content>ui.html</content>
Create a new HTML document and name it ui.html and place it in the same directory as the application.xml file. The first thing you’ll want to do is copy over the AIRAliases.js file from the frameworks folder of the SDK and add a link to it within your HTML document.
<script type="text/javascript" src="AIRAliases.js"></script>
The aliases create shorthand links to all of the Flash-based APIs.
Now is probably a good time to explain how to debug your application.
Debugging our application
So, with our XML file created and HTML file started, let’s try testing our ‘application’. We’ll need the ADL application located in BIN folder of the SDK and tell it to run the application.xml file.
/path/to/adl /path/to/application.xml
You can also just drag the XML file onto ADL and it’ll accomplish the same thing. If you just did that and noticed that your blank application didn’t load, you’d be correct. It’s running but isn’t visible. Which at this point means you’ll have to shut down the ADL process. Sorry about that!
Changing the visibility
You have two ways to make your application visible. You can do it automatically by setting the placing true in the visible tag within the application.xml file.
<visible>true</visible>
The other way is to do it programmatically from within your application. You’d want to do it this way if you had other startup tasks to perform before showing the interface. To turn the UI on programmatically, simple set the visible property of nativeWindow to true.
<script type="text/javascript">
nativeWindow.visible = true;
</script>
Sandbox Security
Now that we have an application that we can see when we start it, it’s time to build the to-do list application. In doing so, you’d probably think that using a JavaScript library is a really good idea — and it can be but there are some limitations within AIR that have to be considered.
An HTML document, by default, runs within the application sandbox. You have full access to the AIR APIs but once the onload event of the window has fired, you’ll have a limited ability to make use of eval and other dynamic script injection approaches. This limits the ability of external sources from gaining access to everything the AIR API offers, such as database and local file system access. You’ll still be able to make use of eval for evaluating JSON responses, which is probably the most important if you wish to consume JSON-based services.
If you wish to create a greater wall of security between AIR and your HTML document loading in external resources, you can create a child sandbox. We won’t need to worry about it for our application so I won’t go any further into it but definitely keep this in mind.
Finally, our application
Getting tired of all this preamble? Let’s actually build our to-do list application. I’ll use jQuery because it’s small and should suit our needs nicely. Let’s begin with some structure:
<body>
<input type="text" id="text" value="">
<input type="button" id="add" value="Add">
<ul id="list"></ul>
</body>
Now we need to wire up that button to actually add a new item to our to-do list.
<script type="text/javascript">
$(document).ready(function(){
// make sure the application is visible
nativeWindow.visible = true;
$('#add').click(function(){
var t = $('#text').val();
if(t)
{
// use DOM methods to create the new list item
var li = document.createElement('li');
// the extra space at the end creates a buffer between the text
// and the delete link we're about to add
li.appendChild(document.createTextNode(t + ' '));
// create the delete link
var del = document.createElement('a');
// this makes it a true link. I feel dirty doing this.
del.setAttribute('href', '#');
del.addEventListener('click', function(evt){
this.parentNode.parentNode.removeChild(this.parentNode);
});
del.appendChild(document.createTextNode('[del]'));
li.appendChild(del);
// append everything to the list
$('#list').append(li);
//reset the text box
$('#text').val('');
}
})
});
</script>
And just like that, we’ve got a to-do list! That’s it! Just never close your application and you’ll remember everything. Okay, that’s not very practical. You need to have some way of storing your to-do items until the next time you open up the application.
Storing Data
You’ve essentially got 4 different ways that you can store data:
Using the local database. AIR comes with SQLLite built in. That means you can create tables and insert, update and select data from that database just like on a web server.
Using the file system. You can also create files on the local machine. You have access to a few folders on the local system such as the documents folder and the desktop.
Using EcryptedLocalStore. I like using the EcryptedLocalStore because it allows you to easily save key/value pairs and have that information encrypted. All this within just a couple lines of code.
Sending the data to a remote API. Our to-do list could sync up with Remember the Milk, for example.
To demonstrate some persistence, we’ll use the file system to store our files. In addition, we’ll let the user specify where the file should be saved. This way, we can create multiple to-do lists, keeping them separate and organized.
The application is now broken down into 4 basic tasks:
Load data from the file system.
Perform any interface bindings.
Manage creating and deleting items from the list.
Save any changes to the list back to the file system.
Loading in data from the file system
When the application starts up, we’ll prompt the user to select a file or specify a new to-do list. Within AIR, there are 3 main file objects: File, FileMode, and FileStream. File handles file and path names, FileMode is used as a parameter for the FileStream to specify whether the file should be read-only or for write access. The FileStream object handles all the read/write activity.
The File object has a number of shortcuts to default paths like the documents folder, the desktop, or even the application store. In this case, we’ll specify the documents folder as the default location and then use the browseForSave method to prompt the user to specify a new or existing file. If the user specifies an existing file, they’ll be asked whether they want to overwrite it.
var store = air.File.documentsDirectory;
var fileStream = new air.FileStream();
store.browseForSave("Choose To-do List");
Then we add an event listener for when the user has selected a file. When the file is selected, we check to see if the file exists and if it does, read in the contents, splitting the file on new lines and creating our list items within the interface.
store.addEventListener(air.Event.SELECT, fileSelected);
function fileSelected()
{
air.trace(store.nativePath);
// load in any stored data
var byteData = new air.ByteArray();
if(store.exists)
{
fileStream.open(store, air.FileMode.READ);
fileStream.readBytes(byteData, 0, store.size);
fileStream.close();
if(byteData.length > 0)
{
var s = byteData.readUTFBytes(byteData.length);
oldlist = s.split(“\r\n”);
// create todolist items
for(var i=0; i < oldlist.length; i++)
{
createItem(oldlist[i], (new Date()).getTime() + i );
}
}
}
}
Perform Interface Bindings
This is similar to before where we set the click event on the Add button but we’ve moved the code to save the list into a separate function.
$('#add').click(function(){
var t = $('#text').val();
if(t){
// create an ID using the time
createItem(t, (new Date()).getTime() );
}
})
Manage creating and deleting items from the list
The list management is now in its own function, similar to before but with some extra information to identify list items and with calls to save our list after each change.
function createItem(t, id)
{
if(t.length == 0) return;
// add it to the todo list
todolist[id] = t;
// use DOM methods to create the new list item
var li = document.createElement('li');
// the extra space at the end creates a buffer between the text
// and the delete link we're about to add
li.appendChild(document.createTextNode(t + ' '));
// create the delete link
var del = document.createElement('a');
// this makes it a true link. I feel dirty doing this.
del.setAttribute('href', '#');
del.addEventListener('click', function(evt){
var id = this.id.substr(1);
delete todolist[id]; // remove the item from the list
this.parentNode.parentNode.removeChild(this.parentNode);
saveList();
});
del.appendChild(document.createTextNode('[del]'));
del.id = 'd' + id;
li.appendChild(del);
// append everything to the list
$('#list').append(li);
//reset the text box
$('#text').val('');
saveList();
}
Save changes to the file system
Any time a change is made to the list, we update the file. The file will always reflect the current state of the list and we’ll never have to click a save button. It just iterates through the list, adding a new line to each one.
function saveList(){
if(store.isDirectory) return;
var packet = '';
for(var i in todolist)
{
packet += todolist[i] + '\r\n';
}
var bytes = new air.ByteArray();
bytes.writeUTFBytes(packet);
fileStream.open(store, air.FileMode.WRITE);
fileStream.writeBytes(bytes, 0, bytes.length);
fileStream.close();
}
One important thing to mention here is that we check if the store is a directory first. The reason we do this goes back to our browseForSave call. If the user cancels the dialog without selecting a file first, then the store points to the documentsDirectory that we set it to initially. Since we haven’t specified a file, there’s no place to save the list.
Hopefully by this point, you’ve been thinking of some cool ways to pimp out your list. Now we need to package this up so that we can let other people use it, too.
Creating a Package
Now that we’ve created our application, we need to package it up so that we can distribute it. This is a two step process. The first step is to create a code signing certificate (or you can pay for one from Thawte which will help authenticate you as an AIR application developer).
To create a self-signed certificate, run the following command. This will create a PFX file that you’ll use to sign your application.
adt -certificate -cn todo24ways 1024-RSA todo24ways.pfx mypassword
After you’ve done that, you’ll need to create the package with the certificate
adt -package -storetype pkcs12 -keystore todo24ways.pfx todo24ways.air application.xml .
The important part to mention here is the period at the end of the command. We’re telling it to package up all files in the current directory.
After that, just run the AIR file, which will install your application and run it.
Important things to remember about AIR
When developing an HTML application, the rendering engine is Webkit. You’ll thank your lucky stars that you aren’t struggling with cross-browser issues. (My personal favourites are multiple backgrounds and border radius!)
Be mindful of memory leaks. Things like Ajax calls and event binding can cause applications to slowly leak memory over time. Web pages are normally short lived but desktop applications are often open for hours, if not days, and you may find your little desktop application taking up more memory than anything else on your machine!
The WebKit runtime itself can also be a memory hog, usually taking about 15MB just for itself. If you create multiple HTML windows, it’ll add another 15MB to your memory footprint. Our little to-do list application shouldn’t be much of a concern, though.
The other important thing to remember is that you’re still essentially running within a Flash environment. While you probably won’t notice this working in small applications, the moment you need to move to multiple windows or need to accomplish stuff beyond what HTML and JavaScript can give you, the need to understand some of the Flash-based elements will become more important.
Lastly, the other thing to remember is that HTML links will load within the AIR application. If you want a link to open in the users web browser, you’ll need to capture that event and handle it on your own. The following code takes the HREF from a clicked link and opens it in the default web browser.
air.navigateToURL(new air.URLRequest(this.href));
Only the beginning
Of course, this is only the beginning of what you can do with Adobe AIR. You don’t have the same level of control as building a native desktop application, such as being able to launch other applications, but you do have more control than what you could have within a web application. Check out the Adobe AIR Developer Center for HTML and Ajax for tutorials and other resources.
Now, go forth and create your desktop applications and hopefully you finish all your shopping before Christmas!
Download the example files. |
2007 |
Jonathan Snook |
jonathansnook |
2007-12-19T00:00:00+00:00 |
https://24ways.org/2007/christmas-is-in-the-air/ |
code |
| 192 |
Cleaner Code with CSS3 Selectors |
The parts of CSS3 that seem to grab the most column inches on blogs and in articles are the shiny bits. Rounded corners, text shadow and new ways to achieve CSS layouts are all exciting and bring with them all kinds of possibilities for web design. However what really gets me, as a developer, excited is a bit more mundane.
In this article I’m going to take a look at some of the ways our front and back-end code will be simplified by CSS3, by looking at the ways we achieve certain visual effects now in comparison to how we will achieve them in a glorious, CSS3-supported future. I’m also going to demonstrate how we can use these selectors now with a little help from JavaScript – which can work out very useful if you find yourself in a situation where you can’t change markup that is being output by some server-side code.
The wonder of nth-child
So why does nth-child get me so excited? Here is a really common situation, the designer would like the tables in the application to look like this:
Setting every other table row to a different colour is a common way to enhance readability of long rows. The tried and tested way to implement this is by adding a class to every other row. If you are writing the markup for your table by hand this is a bit of a nuisance, and if you stick a row in the middle you have to change the rows the class is applied to. If your markup is generated by your content management system then you need to get the server-side code to add that class – if you have access to that code.
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title>Striping every other row - using classes</title>
<style type="text/css">
body {
padding: 40px;
margin: 0;
font: 0.9em Arial, Helvetica, sans-serif;
}
table {
border-collapse: collapse;
border: 1px solid #124412;
width: 600px;
}
th {
border: 1px solid #124412;
background-color: #334f33;
color: #fff;
padding: 0.4em;
text-align: left;
}
td {
padding: 0.4em;
}
tr.odd td {
background-color: #86B486;
}
</style>
</head>
<body>
<table>
<tr>
<th>Name</th>
<th>Cards sent</th>
<th>Cards received</th>
<th>Cards written but not sent</th>
</tr>
<tr>
<td>Ann</td>
<td>40</td>
<td>28</td>
<td>4</td>
</tr>
<tr class="odd">
<td>Joe</td>
<td>2</td>
<td>27</td>
<td>29</td>
</tr>
<tr>
<td>Paul</td>
<td>5</td>
<td>35</td>
<td>2</td>
</tr>
<tr class="odd">
<td>Louise</td>
<td>65</td>
<td>65</td>
<td>0</td>
</tr>
</table>
</body>
</html>
View Example 1
This situation is something I deal with on almost every project, and apart from being an extra thing to do, it just isn’t ideal having the server-side code squirt classes into the markup for purely presentational reasons. This is where the nth-child pseudo-class selector comes in. The server-side code creates a valid HTML table for the data, and the CSS then selects the odd rows with the following selector:
tr:nth-child(odd) td {
background-color: #86B486;
}
View Example 2
The odd and even keywords are very handy in this situation – however you can also use a multiplier here. 2n would be equivalent to the keyword ‘odd’ 3n would select every third row and so on.
Browser support
Sadly, nth-child has pretty poor browser support. It is not supported in Internet Explorer 8 and has somewhat buggy support in some other browsers. Firefox 3.5 does have support. In some situations however, you might want to consider using JavaScript to add this support to browsers that don’t have it. This can be very useful if you are dealing with a Content Management System where you have no ability to change the server-side code to add classes into the markup.
I’m going to use jQuery in these examples as it is very simple to use the same CSS selector used in the CSS to target elements with jQuery – however you could use any library or write your own function to do the same job. In the CSS I have added the original class selector to the nth-child selector:
tr:nth-child(odd) td, tr.odd td {
background-color: #86B486;
}
Then I am adding some jQuery to add a class to the markup once the document has loaded – using the very same nth-child selector that works for browsers that support it.
<script src="http://code.jquery.com/jquery-latest.js"></script>
<script>
$(document).ready(function(){
$("tr:nth-child(odd)").addClass("odd");
});
</script>
View Example 3
We could just add a background colour to the element using jQuery, however I prefer not to mix that information into the JavaScript as if we change the colour on our table rows I would need to remember to change it both in the CSS and in the JavaScript.
Doing something different with the last element
So here’s another thing that we often deal with. You have a list of items all floated left with a right hand margin on each element constrained within a fixed width layout. If each element has the right margin applied the margin on the final element will cause the set to become too wide forcing that last item down to the next row as shown in the below example where I have used a grey border to indicate the fixed width.
Currently we have two ways to deal with this. We can put a negative right margin on the list, the same width as the space between the elements. This means that the extra margin on the final element fills that space and the item doesn’t drop down.
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title>The last item is different</title>
<style type="text/css">
body {
padding: 40px;
margin: 0;
font: 0.9em Arial, Helvetica, sans-serif;
}
div#wrapper {
width: 740px;
float: left;
border: 5px solid #ccc;
}
ul.gallery {
margin: 0 -10px 0 0;
padding: 0;
list-style: none;
}
ul.gallery li {
float: left;
width: 240px;
margin: 0 10px 10px 0;
}
</style>
</head>
<body>
<div id="wrapper">
<ul class="gallery">
<li><img src="xmas1.jpg" alt="baubles" /></li>
<li><img src="xmas2.jpg" alt="star" /></li>
<li><img src="xmas3.jpg" alt="wreath" /></li>
</ul>
</div>
</body>
</html>
View Example 4
The other solution will be to put a class on the final element and in the CSS remove the margin for this class.
ul.gallery li.last {
margin-right: 0;
}
This second solution may not be easy if the content is generated from server-side code that you don’t have access to change.
It could all be so different. In CSS3 we have marvellously common-sense selectors such as last-child, meaning that we can simply add rules for the last list item.
ul.gallery li:last-child {
margin-right: 0;
}
View Example 5
This removed the margin on the li which is the last-child of the ul with a class of gallery. No messing about sticking classes on the last item, or pushing the width of the item out wit a negative margin.
If this list of items repeated ad infinitum then you could also use nth-child for this task. Creating a rule that makes every 3rd element margin-less.
ul.gallery li:nth-child(3n) {
margin-right: 0;
}
View Example 6
A similar example is where the designer has added borders to the bottom of each element – but the last item does not have a border or is in some other way different. Again, only a class added to the last element will save you here if you cannot rely on using the last-child selector.
Browser support for last-child
The situation for last-child is similar to that of nth-child, in that there is no support in Internet Explorer 8. However, once again it is very simple to replicate the functionality using jQuery. Adding our .last class to the last list item.
$("ul.gallery li:last-child").addClass("last");
We could also use the nth-child selector to add the .last class to every third list item.
$("ul.gallery li:nth-child(3n)").addClass("last");
View Example 7
Fun with forms
Styling forms can be a bit of a trial, made difficult by the fact that any CSS applied to the input element will effect text fields, submit buttons, checkboxes and radio buttons. As developers we are left adding classes to our form fields to differentiate them. In most builds all of my text fields have a simple class of text whereas I wouldn’t dream of adding a class of para to every paragraph element in a document.
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title>Syling form fields</title>
<style type="text/css">
body {
padding: 40px;
margin: 0;
font: 0.9em Arial, Helvetica, sans-serif;
}
form div {
clear: left;
padding: 0 0 0.8em 0;
}
form label {
float: left;
width: 120px;
}
form .text, form textarea {
border:1px solid #333;
padding: 0.2em;
width: 400px;
}
form .button {
border: 1px solid #333;
background-color: #eee;
color: #000;
padding: 0.1em;
}
</style>
</head>
<body>
<h1>Send your Christmas list to Santa</h1>
<form method="post" action="" id="christmas-list">
<div><label for="fName">Name</label>
<input type="text" name="fName" id="fName" class="text" /></div>
<div><label for="fEmail">Email address</label>
<input type="text" name="fEmail" id="fEmail" class="text" /></div>
<div><label for="fList">Your list</label>
<textarea name="fList" id="fList" rows="10" cols="30"></textarea></div>
<div><input type="submit" name="btnSubmit" id="btnSubmit" value="Submit" class="button" ></div>
</form>
</body>
</html>
View Example 8
Attribute selectors provide a way of targeting elements by looking at the attributes of those elements. Unlike the other examples in this article which are CSS3 selectors, the attribute selector is actually a CSS2.1 selector – it just doesn’t get much use because of lack of support in Internet Explorer 6. Using attribute selectors we can write rules for text inputs and form buttons without needing to add any classes to the markup. For example after removing the text and button classes from my text and submit button input elements I can use the following rules to target them:
form input[type="text"] {
border: 1px solid #333;
padding: 0.2em;
width: 400px;
}
form input[type="submit"]{
border: 1px solid #333;
background-color: #eee;
color: #000;
padding: 0.1em;
}
View Example 9
Another problem that I encounter with forms is where I am using CSS to position my labels and form elements by floating the labels. This works fine as long as I want all of my labels to be floated, however sometimes we get a set of radio buttons or a checkbox, and I don’t want the label field to be floated. As you can see in the below example the label for the checkbox is squashed up into the space used for the other labels, yet it makes more sense for the checkbox to display after the text.
I could use a class on this label element however CSS3 lets me to target the label attribute directly by looking at the value of the for attribute.
label[for="fOptIn"] {
float: none;
width: auto;
}
Being able to precisely target attributes in this way is incredibly useful, and once IE6 is no longer an issue this will really help to clean up our markup and save us from having to create all kinds of special cases when generating this markup on the server-side.
Browser support
The news for attribute selectors is actually pretty good with Internet Explorer 7+, Firefox 2+ and all other modern browsers all having support. As I have already mentioned this is a CSS2.1 selector and so we really should expect to be able to use it as we head into 2010! Internet Explorer 7 has slightly buggy support and will fail on the label example shown above however I discovered a workaround in the Sitepoint CSS reference comments. Adding the selector label[htmlFor="fOptIn"] to the correct selector will create a match for IE7.
IE6 does not support these selector but, once again, you can use jQuery to plug the holes in IE6 support. The following jQuery will add the text and button classes to your fields and also add a checks class to the label for the checkbox, which you can use to remove the float and width for this element.
$('form input[type="submit"]').addClass("button");
$('form input[type="text"]').addClass("text");
$('label[for="fOptIn"]').addClass("checks");
View Example 10
The selectors I’ve used in this article are easy to overlook as we do have ways to achieve these things currently. As developers – especially when we have frameworks and existing code that cope with these situations – it is easy to carry on as we always have done.
I think that the time has come to start to clean up our front and backend code and replace our reliance on classes with these more advanced selectors. With the help of a little JavaScript almost all users will still get the full effect and, where we are dealing with purely visual effects, there is definitely a case to be made for not worrying about the very small percentage of people with old browsers and no JavaScript. They will still receive a readable website, it may just be missing some of the finesse offered to the modern browsing experience. |
2009 |
Rachel Andrew |
rachelandrew |
2009-12-20T00:00:00+00:00 |
https://24ways.org/2009/cleaner-code-with-css3-selectors/ |
code |
| 253 |
Clip Paths Know No Bounds |
CSS Shapes are getting a lot of attention as browser support has increased for properties like shape-outside and clip-path. There are a few ways that we can use CSS Shapes, in particular with the clip-path property, that are not necessarily evident at first glance.
The basics of a clip path
Before we dig into specific techniques to expand on clip paths, we should first take a look at a basic shape and clip-path. Clip paths can apply a CSS Shape such as a circle(), ellipse(), inset(), or the flexible polygon() to any element. Everywhere in the element that is not within the bounds of our shape will be visually removed.
Using the polygon shape function, for example, we can create triangles, stars, or other straight-edged shapes as on Bennett Feely’s Clippy. While fixed units like pixels can be used when defining vertices/points (where the sides meet), percentages will give more flexibility to adapt to the element’s dimensions.
See the Pen Clip Path Box by Dan Wilson (@danwilson) on CodePen.
So for an octagon, we can set eight x, y pairs of percentages to define those points. In this case we start 30% into the width of the box for the first x and at the top of the box for the y and go clockwise. The visible area becomes the interior of the shape made by connecting these points with straight lines.
clip-path: polygon(
30% 0%,
70% 0%,
100% 30%,
100% 70%,
70% 100%,
30% 100%,
0% 70%,
0% 30%
);
A shape with less vertices than the eye can see
It’s reasonable to look at the polygon() function and assume that we need to have one pair of x, y coordinates for every point in our shape. However, we gain some flexibility by thinking outside the box — or more specifically when we think outside the range of 0% - 100%.
Our element’s box model will be the ultimate boundary for a clip-path, but we can still define points that exist beyond that natural box for an element.
See the Pen CSS Shapes Know No Bounds by Dan Wilson (@danwilson) on CodePen.
By going beyond the 0% - 100% range we can turn a polygon with three points into a quadrilateral, a pentagon, or a hexagon. In this example the shapes used are all similar triangles defining three points, but due to exceeding the bounds for our element box we visually see one triangle and two pentagons.
Our earlier octagon can similarly be made with only four points.
See the Pen Octagon with four points by Dan Wilson (@danwilson) on CodePen.
Multiple shapes, one clip path
We can lean on this power of going beyond the bounds of our element to also create more than one visual shape with a single polygon().
See the Pen Multiple shapes from one clip-path by Dan Wilson (@danwilson) on CodePen.
Depending on how we lay it out we can make each shape directly, but since we know we can move around in the space beyond the element’s box, we can draw extra lines to help us get where we need to go next as needed.
It can also help us in slicing an element. Combined with CSS Variables, we can work with overlapping elements and clip each one into alternating strips. This example is two elements, each divided into a few rectangles.
See the Pen 24w: Sliced Icon by Dan Wilson (@danwilson) on CodePen.
Different shapes with fill rules
A polygon() is not just a collection of points. There is one more key piece to its puzzle according to the specification — the Fill Rule. The default value we have been using so far is nonzero, and the second option is evenodd. These two values help determine what is considered inside and outside the shape.
See the Pen A Star Multiways by Dan Wilson (@danwilson) on CodePen.
As lines intersect we can get into situations where pieces seemingly on the inside can be considered outside the shape boundary. When using the evenodd fill rule, we can determine if a given point is inside or outside the boundary by drawing a ray from the point in any direction. If the ray crosses an even number of the clip path’s lines, the point is considered outside, and if it crosses an odd number the point is inside.
Order of operations
It is important to note that there are many CSS properties that affect the final composited appearance of an element via CSS Filters, Blend Modes, and more.
These compositing effects are applied in the order:
CSS Filters (e.g. filter: blur(2px))
Clipping (e.g. what this article is about)
Masking (Clipping’s cousin)
Blend Modes (e.g. mix-blend-mode: multiply)
Opacity
This means if we want to have a star shape and blur it, the blur will happen before the clip. And since blurs are most noticeable around the edge of an element box, the effect might be completely lost since we have clipped away the element’s box edges.
See the Pen Order of Filter + Clip by Dan Wilson (@danwilson) on CodePen.
If we want the edges of the star to be blurred, we do have the option to wrap our clipped element in a blurred parent element. The inner element will be rendered first (with its star clip) and then the parent will blur its contents normally.
Revealing content with animation
CSS Shapes can be transitioned and animated, allowing us to animate the visual area of our element without affecting the content within. For example, we can start with visually hidden content (fully clipped) and grow the clip path to reveal the content within. The important caveat for polygon() is that the number of points need to be the same for each keyframe, as well as the fill rule. Otherwise the browser will not have enough information to interpolate the intermediate values.
See the Pen Clip Path Shape Reveal by Dan Wilson (@danwilson) on CodePen.
Don’t keep CSS Shapes in a box
Clip paths give us some interesting new possibilities, especially when we think of them as more than just basic shapes. We may be heavily modifying the visual representation of our elements with clip-path, but the underlying content remains unchanged and accessible which makes this property fairly powerful. |
2018 |
Dan Wilson |
danwilson |
2018-12-20T00:00:00+00:00 |
https://24ways.org/2018/clip-paths-know-no-bounds/ |
code |
| 8 |
Coding Towards Accessibility |
“Can we make it AAA-compliant?” – does this question strike fear into your heart? Maybe for no other reason than because you will soon have to wade through the impenetrable WCAG documentation once again, to find out exactly what AAA-compliant means?
I’m not here to talk about that.
The Web Content Accessibility Guidelines are a comprehensive and peer-reviewed resource which we’re lucky to have at our fingertips. But they are also a pig to read, and they may have contributed to the sense of mystery and dread with which some developers associate the word accessibility.
This Christmas, I want to share with you some thoughts and some practical tips for building accessible interfaces which you can start using today, without having to do a ton of reading or changing your tools and workflow.
But first, let’s clear up a couple of misconceptions.
Dreary, flat experiences
I recently built a front-end framework for the Post Office. This was a great gig for a developer, but when I found out about my client’s stringent accessibility requirements I was concerned that I’d have to scale back what was quite a complex set of visual designs.
Sites like Jakob Neilsen’s old workhorse useit.com and even the pioneering GOV.UK may have to shoulder some of the blame for this. They put a premium on usability and accessibility over visual flourish. (Although, in fairness to Mr Neilsen, his new site nngroup.com is really quite a snazzy affair, comparatively.)
Of course, there are other reasons for these sites’ aesthetics — and it’s not because of the limitations of the form. You can make an accessible site look as glossy or as plain as you want it to look. It’s always our own ingenuity and attention to detail that are going to be the limiting factors.
Synecdoche
We must always guard against the tendency to assume that catering to screen readers means we have the whole accessibility ballgame covered.
There’s so much more to accessibility than assistive technology, as you know. And within the field of assistive technology there are plenty of other devices for us to consider.
Planning to accommodate all these users and devices can be daunting. When I first started working in this field I thought that the breadth of technology was prohibitive. I didn’t even know what a screen reader looked like. (I assumed they were big and heavy, perhaps like an old typewriter, and certainly they would be expensive and difficult to fathom.) This is nonsense, of course. Screen reader emulators are readily available as browser extensions and can be activated in seconds. Chromevox and Fangs are both excellent and you should download one or the other right now.
But the really good news is that you can emulate many other types of assistive technology without downloading a byte. And this is where we move from misconceptions into some (hopefully) useful advice.
The mouse trap
The simplest and most effective way to improve your abilities as a developer of accessible interfaces is to unplug your mouse.
Keyboard operation has its own WCAG chapter, because most users of assistive technology are navigating the web using only their keyboards. You can go some way towards putting yourself into their shoes so easily — just by ditching a peripheral.
Learning this was a lightbulb moment for me. When I build interfaces I am constantly flicking between code and the browser, testing or viewing the changes I have made. Now, instead of checking a new element once, I check it twice: once with my mouse and then again without.
Don’t just :hover
The reality is that when you first start doing this you can find your site becomes unusable straightaway. It’s easy to lose track of which element is in focus as you hit the tab key repeatedly.
One of the easiest changes you can make to your coding practice is to add :focus and :active pseudo-classes to every hover state that you write. I’m still amazed at how many sites fail to provide a decent focus state for links (and despite previous 24 ways authors in 2007 and 2009 writing on this same issue!).
You may find that in some cases it makes sense to have something other than, or in addition to, the hover state on focus, but start with the hover state that your designer has taken the time to provide you with. It’s a tiny change and there is no downside. So instead of this:
.my-cool-link:hover {
background-color: MistyRose ;
}
…try writing this:
.my-cool-link:hover,
.my-cool-link:focus,
.my-cool-link:active {
background-color: MistyRose ;
}
I’ve toyed with the idea of making a Sass mixin to take care of this for me, but I haven’t yet. I worry that people reading my code won’t see that I’m explicitly defining my focus and active states so I take the hit and write my hover rules out longhand.
JavaScript can play, too
This was another revelation for me. Keyboard-only navigation doesn’t necessitate a JavaScript-free experience, and up-to-date screen readers can execute JavaScript. So we’re able to create complex JavaScript-driven interfaces which all users can interact with.
Some of the hard work has already been done for us. First, there are already conventions around keyboard-driven interfaces. Think about the last time you viewed a photo album on Facebook. You can use the arrow keys to switch between photos, and the escape key closes whichever lightbox-y UI thing Facebook is showing its photos in this week. Arrow keys (up/down as well as left/right) for progression through content; Escape to back out of something; Enter or space bar to indicate a positive intention — these are established keyboard conventions which we can apply to our interfaces to improve their accessiblity.
Of course, by doing so we are improving our interfaces in general, giving all users the option to switch between keyboard and mouse actions as and when it suits them.
Second, this guy wants to help you out. Hans Hillen is a developer who has done a great deal of work around accessibility and JavaScript-powered interfaces. Along with The Paciello Group he has created a version of the jQuery UI library which has been fully optimised for keyboard navigation and screen reader use. It’s a fantastic reference which I revisit all the time
I’m not a huge fan of the jQuery UI library. It’s a pain to style and the code is a bit bloated. So I’ve not used this demo as a code resource to copy wholesale. I use it by playing with the various components and seeing how they react to keyboard controls. Each component is also fully marked up with the relevant ARIA roles to improve screen reader announcement where possible (more on this below).
Coding for accessibility promotes good habits
This is a another observation around accessibility and JavaScript. I noticed an improvement in the structure and abstraction of my code when I started adding keyboard controls to my interface elements.
Your code has to become more modular and event-driven, because any number of events could trigger the same interaction. A mouse-click, the Enter key and the space bar could all conceivably trigger the same open function on a collapsed accordion element. (And you want to keep things DRY, don’t you?)
If you aren’t already in the habit of separating out your interface functionality into discrete functions, you will be soon.
var doSomethingCool = function(){
// Do something cool here.
}
// Bind function to a button click - pretty vanilla
$('.myCoolButton').on('click', function(){
doSomethingCool();
return false;
});
// Bind the same function to a range of keypresses
$(document).keyup(function(e){
switch(e.keyCode) {
case 13: // enter
case 32: // spacebar
doSomethingCool();
break;
case 27: // escape
doSomethingElse();
break;
}
});
To be honest, if you’re doing complex UI stuff with JavaScript these days, or if you’ve been building any responsive interfaces which rely on JavaScript, then you are most likely working with an application framework such as Backbone, Angular or Ember, so an abstraced and event-driven application structure will be familar to you. It should be super easy for you to start helping out your keyboard-only users if you aren’t already — just add a few more event bindings into your UI layer!
Manipulating the tab order
So, you’ve adjusted your mindset and now you test every change to your codebase using a keyboard as well as a mouse. You’ve applied all your hover states to :focus and :active so you can see where you’re tabbing on the page, and your interactive components react seamlessly to a mixture of mouse and keyboard commands. Feels good, right?
There’s another level of optimisation to consider: manipulating the tab order. Certain DOM elements are naturally part of the tab order, and others are excluded. Links and input elements are the main elements included in the tab order, and static elements like paragraphs and headings are excluded. What if you want to make a static element ‘tabbable’?
A good example would be in an expandable accordion component. Each section of the accordion should be separated by a heading, and there’s no reason to make that heading into a link simply because it’s interactive.
<div class="accordion-widget">
<h3>Tyrannosaurus</h3>
<p>Tyrannosaurus; meaning "tyrant lizard"...<p>
<h3>Utahraptor</h3>
<p>Utahraptor is a genus of theropod dinosaurs...<p>
<h3>Dromiceiomimus</h3>
<p>Ornithomimus is a genus of ornithomimid dinosaurs...<p>
</div>
Adding the heading elements to the tab order is trivial. We just set their tabindex attribute to zero. You could do this on the server or the client. I prefer to do it with JavaScript as part of the accordion setup and initialisation process.
$('.accordion-widget h3').attr('tabindex', '0');
You can apply this trick in reverse and take elements out of the tab order by setting their tabindex attribute to −1, or change the tab order completely by using other integers. This should be done with great care, if at all. You have to be sure that the markup you remove from the tab order comes out because it genuinely improves the keyboard interaction experience. This is hard to validate without user testing. The danger is that developers will try to sweep complicated parts of the UI under the carpet by taking them out of the tab order. This would be considered a dark pattern — at least on my team!
A farewell ARIA
This is where things can get complex, and I’m no expert on the ARIA specification: I feel like I’ve only dipped my toe into this aspect of coding for accessibility. But, as with WCAG, I’d like to demystify things a little bit to encourage you to look into this area further yourself.
ARIA roles are of most benefit to screen reader users, because they modify and augment screen reader announcements.
Let’s take our dinosaur accordion from the previous section. The markup is semantic, so a screen reader that can’t handle JavaScript will announce all the content within the accordion, no problem.
But modern screen readers can deal with JavaScript, and this means that all the lovely dino information beneath each heading has probably been hidden on document.ready, when the accordion initialised. It might have been hidden using display:none, which prevents a screen reader from announcing content. If that’s as far as you have gone, then you’ve committed an accessibility sin by hiding content from screen readers. Your user will hear a set of headings being announced, with no content in between. It would sound something like this if you were using Chromevox:
> Tyrannosaurus. Heading Three.
> Utahraptor. Heading Three.
> Dromiceiomimus. Heading Three.
We can add some ARIA magic to the markup to improve this, using the tablist role. Start by adding a role of tablist to the widget, and roles of tab and tabpanel to the headings and paragraphs respectively. Set boolean values for aria-selected, aria-hidden and aria-expanded. The markup could end up looking something like this.
<div class="accordion-widget" role="tablist">
<!-- T-rex -->
<h3 role="tab"
tabindex="0"
id="tab-2"
aria-controls="panel-2"
aria-selected="false">Utahraptor</h3>
<p role="tabpanel"
id="panel-2"
aria-labelledby="tab-2"
aria-expanded="false"
aria-hidden="true">Utahraptor is a genus of theropod dinosaurs...</p>
<!-- Dromiceiomimus -->
</div>
Now, if a screen reader user encounters this markup they will hear the following:
> Tyrannosaurus. Tab not selected; one of three.
> Utahraptor. Tab not selected; two of three.
> Dromiceiomimus. Tab not selected; three of three.
You could add arrow key events to help the user browse up and down the tab list items until they find one they like.
Your accordion open() function should update the ARIA boolean values as well as adding whatever classes and animations you have built in as standard. Your users know that unselected tabs are meant to be interacted with, so if a user triggers the open function (say, by hitting Enter or the space bar on the second item) they will hear this:
> Utahraptor. Selected; two of three.
The paragraph element for the expanded item will not be hidden by your CSS, which means it will be announced as normal by the screen reader.
This kind of thing makes so much more sense when you have a working example to play with. Again, I refer you to the fantastic resource that Hans Hillen has put together: this is his take on an accessible accordion, on which much of my example is based.
Conclusion
Getting complex interfaces right for all of your users can be difficult — there’s no point pretending otherwise. And there’s no substitute for user testing with real users who navigate the web using assistive technology every day. This kind of testing can be time-consuming to recruit for and to conduct. On top of this, we now have accessibility on mobile devices to contend with. That’s a huge area in itself, and it’s one which I have not yet had a chance to research properly.
So, there’s lots to learn, and there’s lots to do to get it right. But don’t be disheartened. If you have read this far then I’ll leave you with one final piece of advice: don’t wait.
Don’t wait until you’re building a site which mandates AAA-compliance to try this stuff out. Don’t wait for a client with the will or the budget to conduct the full spectrum of user testing to come along. Unplug your mouse, and start playing with your interfaces in a new way. You’ll be surprised at the things that you learn and the issues you uncover.
And the next time an true accessibility project comes along, you will be way ahead of the game. |
2013 |
Charlie Perrins |
charlieperrins |
2013-12-03T00:00:00+00:00 |
https://24ways.org/2013/coding-towards-accessibility/ |
code |
| 162 |
Conditional Love |
“Browser.” The four-letter word of web design.
I mean, let’s face it: on the good days, when things just work in your target browsers, it’s marvelous. The air smells sweeter, birds’ songs sound more melodious, and both your design and your code are looking sharp.
But on the less-than-good days (which is, frankly, most of them), you’re compelled to tie up all your browsers in a sack, heave them into the nearest river, and start designing all-imagemap websites. We all play favorites, after all: some will swear by Firefox, Opera fans are allegedly legion, and others still will frown upon anything less than the latest WebKit nightly.
Thankfully, we do have an out for those little inconsistencies that crop up when dealing with cross-browser testing: CSS patches.
Spare the Rod, Hack the Browser
Before committing browsercide over some rendering bug, a designer will typically reach for a snippet of CSS fix the faulty browser. Historically referred to as “hacks,” I prefer Dan Cederholm’s more client-friendly alternative, “patches”.
But whatever you call them, CSS patches all work along the same principle: supply the proper property value to the good browsers, while giving higher maintenance other browsers an incorrect value that their frustrating idiosyncratic rendering engine can understand.
Traditionally, this has been done either by exploiting incomplete CSS support:
#content {
height: 1%; // Let's force hasLayout for old versions of IE.
line-height: 1.6;
padding: 1em;
}
html>body #content {
height: auto; // Modern browsers get a proper height value.
}
or by exploiting bugs in their rendering engine to deliver alternate style rules:
#content p {
font-size: .8em;
/* Hide from Mac IE5 \*/
font-size: .9em;
/* End hiding from Mac IE5 */
}
We’ve even used these exploits to serve up whole stylesheets altogether:
@import url("core.css");
@media tty {
i{content:"\";/*" "*/}} @import 'windows-ie5.css'; /*";}
}/* */
The list goes on, and on, and on. For every browser, for every bug, there’s a patch available to fix some rendering bug.
But after some time working with standards-based layouts, I’ve found that CSS patches, as we’ve traditionally used them, become increasingly difficult to maintain. As stylesheets are modified over the course of a site’s lifetime, inline fixes we’ve written may become obsolete, making them difficult to find, update, or prune out of our CSS. A good patch requires a constant gardener to ensure that it adds more than just bloat to a stylesheet, and inline patches can be very hard to weed out of a decently sized CSS file.
Giving the Kids Separate Rooms
Since I joined Airbag Industries earlier this year, every project we’ve worked on has this in the head of its templates:
<link rel="stylesheet" href="-/css/screen/main.css" type="text/css" media="screen, projection" />
<!--[if lt IE 7]>
<link rel="stylesheet" href="-/css/screen/patches/win-ie-old.css" type="text/css" media="screen, projection" />
<![endif]-->
<!--[if gte IE 7]>
<link rel="stylesheet" href="-/css/screen/patches/win-ie7-up.css" type="text/css" media="screen, projection" />
<![endif]-->
The first element is, simply enough, a link element that points to the project’s main CSS file. No patches, no hacks: just pure, modern browser-friendly style rules. Which, nine times out of ten, will net you a design that looks like spilled eggnog in various versions of Internet Explorer.
But don’t reach for the mulled wine quite yet. Immediately after, we’ve got a brace of conditional comments wrapped around two other link elements. These odd-looking comments allow us to selectively serve up additional stylesheets just to the version of IE that needs them. We’ve got one for IE 6 and below:
<!--[if lt IE 7]>
<link rel="stylesheet" href="-/css/screen/patches/win-ie-old.css" type="text/css" media="screen, projection" />
<![endif]-->
And another for IE7 and above:
<!--[if gte IE 7]>
<link rel="stylesheet" href="-/css/screen/patches/win-ie7-up.css" type="text/css" media="screen, projection" />
<![endif]-->
Microsoft’s conditional comments aren’t exactly new, but they can be a valuable alternative to cooking CSS patches directly into a master stylesheet. And though they’re not a W3C-approved markup structure, I think they’re just brilliant because they innovate within the spec: non-IE devices will assume that the comments are just that, and ignore the markup altogether.
This does, of course, mean that there’s a little extra markup in the head of our documents. But this approach can seriously cut down on the unnecessary patches served up to the browsers that don’t need them. Namely, we no longer have to write rules like this in our main stylesheet:
#content {
height: 1%; // Let's force hasLayout for old versions of IE.
line-height: 1.6;
padding: 1em;
}
html>body #content {
height: auto; // Modern browsers get a proper height value.
}
Rather, we can simply write an un-patched rule in our core stylesheet:
#content {
line-height: 1.6;
padding: 1em;
}
And now, our patch for older versions of IE goes in—you guessed it—the stylesheet for older versions of IE:
#content {
height: 1%;
}
The hasLayout patch is applied, our design’s repaired, and—most importantly—the patch is only seen by the browser that needs it. The “good” browsers don’t have to incur any added stylesheet weight from our IE patches, and Internet Explorer gets the conditional love it deserves.
Most importantly, this “compartmentalized” approach to CSS patching makes it much easier for me to patch and maintain the fixes applied to a particular browser. If I need to track down a bug for IE7, I don’t need to scroll through dozens or hundreds of rules in my core stylesheet: instead, I just open the considerably slimmer IE7-specific patch file, make my edits, and move right along.
Even Good Children Misbehave
While IE may occupy the bulk of our debugging time, there’s no denying that other popular, modern browsers will occasionally disagree on how certain bits of CSS should be rendered. But without something as, well, pimp as conditional comments at our disposal, how do we bring the so-called “good browsers” back in line with our design?
Assuming you’re loving the “one patch file per browser” model as much as I do, there’s just one alternative: JavaScript.
function isSaf() {
var isSaf = (document.childNodes && !document.all && !navigator.taintEnabled && !navigator.accentColorName) ? true : false;
return isSaf;
}
function isOp() {
var isOp = (window.opera) ? true : false;
return isOp;
}
Instead of relying on dotcom-era tactics of parsing the browser’s user-agent string, we’re testing here for support for various DOM objects, whose presence or absence we can use to reasonably infer the browser we’re looking at. So running the isOp() function, for example, will test for Opera’s proprietary window.opera object, and thereby accurately tell you if your user’s running Norway’s finest browser.
With scripts such as isOp() and isSaf() in place, you can then reasonably test which browser’s viewing your content, and insert additional link elements as needed.
function loadPatches(dir) {
if (document.getElementsByTagName() && document.createElement()) {
var head = document.getElementsByTagName("head")[0];
if (head) {
var css = new Array();
if (isSaf()) {
css.push("saf.css");
} else if (isOp()) {
css.push("opera.css");
}
if (css.length) {
var link = document.createElement("link");
link.setAttribute("rel", "stylesheet");
link.setAttribute("type", "text/css");
link.setAttribute("media", "screen, projection");
for (var i = 0; i < css.length; i++) {
var tag = link.cloneNode(true);
tag.setAttribute("href", dir + css[0]);
head.appendChild(tag);
}
}
}
}
}
Here, we’re testing the results of isSaf() and isOp(), one after the other. For each function that returns true, then the name of a new stylesheet is added to the oh-so-cleverly named css array. Then, for each entry in css, we create a new link element, point it at our patch file, and insert it into the head of our template.
Fire it up using your favorite onload or DOMContentLoaded function, and you’re good to go.
Scripteat Emptor
At this point, some of the audience’s more conscientious ‘scripters may be preparing to lob figgy pudding at this author’s head. And that’s perfectly understandable; relying on JavaScript to patch CSS chafes a bit against the normally clean separation we have between our pages’ content, presentation, and behavior layers.
And beyond the philosophical concerns, this approach comes with a few technical caveats attached:
Browser detection? So un-133t.
Browser detection is not something I’d typically recommend. Whenever possible, a proper DOM script should check for the support of a given object or method, rather than the device with which your users view your content.
It’s JavaScript, so don’t count on it being available.
According to one site, roughly four percent of Internet users don’t have JavaScript enabled. Your site’s stats might be higher or lower than this number, but still: don’t expect that every member of your audience will see these additional stylesheets, and ensure that your content’s still accessible with JS turned off.
Be a constant gardener.
The sample isSaf() and isOp() functions I’ve written will tell you if the user’s browser is Safari or Opera. As a result, stylesheets written to patch issues in an old browser may break when later releases repair the relevant CSS bugs.
You can, of course, add logic to these simple little scripts to serve up version-specific stylesheets, but that way madness may lie. In any event, test your work vigorously, and keep testing it when new versions of the targeted browsers come out. Make sure that a patch written today doesn’t become a bug tomorrow.
Patching Firefox, Opera, and Safari isn’t something I’ve had to do frequently: still, there have been occasions where the above script’s come in handy. Between conditional comments, careful CSS auditing, and some judicious JavaScript, browser-based bugs can be handled with near-surgical precision.
So pass the ‘nog. It’s patchin’ time. |
2007 |
Ethan Marcotte |
ethanmarcotte |
2007-12-15T00:00:00+00:00 |
https://24ways.org/2007/conditional-love/ |
code |
| 320 |
DOM Scripting Your Way to Better Blockquotes |
Block quotes are great. I don’t mean they’re great for indenting content – that would be an abuse of the browser’s default styling. I mean they’re great for semantically marking up a chunk of text that is being quoted verbatim. They’re especially useful in blog posts.
<blockquote>
<p>Progressive Enhancement, as a label for a strategy for Web design,
was coined by Steven Champeon in a series of articles and presentations
for Webmonkey and the SxSW Interactive conference.</p>
</blockquote>
Notice that you can’t just put the quoted text directly between the <blockquote> tags. In order for your markup to be valid, block quotes may only contain block-level elements such as paragraphs.
There is an optional cite attribute that you can place in the opening <blockquote> tag. This should contain a URL containing the original text you are quoting:
<blockquote cite="http://en.wikipedia.org/wiki/Progressive_Enhancement">
<p>Progressive Enhancement, as a label for a strategy for Web design,
was coined by Steven Champeon in a series of articles and presentations
for Webmonkey and the SxSW Interactive conference.</p>
</blockquote>
Great! Except… the default behavior in most browsers is to completely ignore the cite attribute. Even though it contains important and useful information, the URL in the cite attribute is hidden.
You could simply duplicate the information with a hyperlink at the end of the quoted text:
<blockquote cite="http://en.wikipedia.org/wiki/Progressive_Enhancement">
<p>Progressive Enhancement, as a label for a strategy for Web design,
was coined by Steven Champeon in a series of articles and presentations
for Webmonkey and the SxSW Interactive conference.</p>
<p class="attribution">
<a href="http://en.wikipedia.org/wiki/Progressive_Enhancement">source</a>
</p>
</blockquote>
But somehow it feels wrong to have to write out the same URL twice every time you want to quote something. It could also get very tedious if you have a lot of quotes.
Well, “tedious” is no problem to a programming language, so why not use a sprinkling of DOM Scripting? Here’s a plan for generating an attribution link for every block quote with a cite attribute:
Write a function called prepareBlockquotes.
Begin by making sure the browser understands the methods you will be using.
Get all the blockquote elements in the document.
Start looping through each one.
Get the value of the cite attribute.
If the value is empty, continue on to the next iteration of the loop.
Create a paragraph.
Create a link.
Give the paragraph a class of “attribution”.
Give the link an href attribute with the value from the cite attribute.
Place the text “source” inside the link.
Place the link inside the paragraph.
Place the paragraph inside the block quote.
Close the for loop.
Close the function.
Here’s how that translates to JavaScript:
function prepareBlockquotes() {
if (!document.getElementsByTagName || !document.createElement || !document.appendChild) return;
var quotes = document.getElementsByTagName("blockquote");
for (var i=0; i<quotes.length; i++) {
var source = quotes[i].getAttribute("cite");
if (!source) continue;
var para = document.createElement("p");
var link = document.createElement("a");
para.className = "attribution";
link.setAttribute("href",source);
link.appendChild(document.createTextNode("source"));
para.appendChild(link);
quotes[i].appendChild(para);
}
}
Now all you need to do is trigger that function when the document has loaded:
window.onload = prepareBlockquotes;
Better yet, use Simon Willison’s handy addLoadEvent function to queue this function up with any others you might want to execute when the page loads.
That’s it. All you need to do is save this function in a JavaScript file and reference that file from the head of your document using <script> tags.
You can style the attribution link using CSS. It might look good aligned to the right with a smaller font size.
If you’re looking for something to do to keep you busy this Christmas, I’m sure that this function could be greatly improved. Here are a few ideas to get you started:
Should the text inside the generated link be the URL itself?
If the block quote has a title attribute, how would you take its value and use it as the text inside the generated link?
Should the attribution paragraph be placed outside the block quote? If so, how would you that (remember, there is an insertBefore method but no insertAfter)?
Can you think of other instances of useful information that’s locked away inside attributes? Access keys? Abbreviations? |
2005 |
Jeremy Keith |
jeremykeith |
2005-12-05T00:00:00+00:00 |
https://24ways.org/2005/dom-scripting-your-way-to-better-blockquotes/ |
code |
| 31 |
Dealing with Emergencies in Git |
The stockings were hung by the chimney with care,
In hopes that version control soon would be there.
This summer I moved to the UK with my partner, and the onslaught of the Christmas holiday season began around the end of October (October!). It does mean that I’ve had more than a fair amount of time to come up with horrible Git analogies for this article. Analogies, metaphors, and comparisons help the learner hook into existing mental models about how a system works. They only help, however, if the learner has enough familiarity with the topic at hand to make the connection between the old and new information.
Let’s start by painting an updated version of Clement Clarke Moore’s Christmas living room. Empty stockings are hung up next to the fireplace, waiting for Saint Nicholas to come down the chimney and fill them with small treats. Holiday treats are scattered about. A bowl of mixed nuts, the holiday nutcracker, and a few clementines. A string of coloured lights winds its way up an evergreen.
Perhaps a few of these images are familiar, or maybe they’re just settings you’ve seen in a movie. It doesn’t really matter what the living room looks like though. The important thing is to ground yourself in your own experiences before tackling a new subject. Instead of trying to brute-force your way into new information, as an adult learner constantly ask yourself: ‘What is this like? What does this remind me of? What do I already know that I can use to map out this new territory?’ It’s okay if the map isn’t perfect. As you refine your understanding of a new topic, you’ll outgrow the initial metaphors, analogies, and comparisons.
With apologies to Mr. Moore, let’s give it a try.
Getting Interrupted in Git
When on the roof there arose such a clatter!
You’re happily working on your software project when all of a sudden there are freaking reindeer on the roof! Whatever you’ve been working on is going to need to wait while you investigate the commotion.
If you’ve got even a little bit of experience working with Git, you know that you cannot simply change what you’re working on in times of emergency. If you’ve been doing work, you have a dirty working directory and you cannot change branches, or push your work to a remote repository while in this state.
Up to this point, you’ve probably dealt with emergencies by making a somewhat useless commit with a message something to the effect of ‘switching branches for a sec’. This isn’t exactly helpful to future you, as commits should really contain whole ideas of completed work. If you get interrupted, especially if there are reindeer on the roof, the chances are very high that you weren’t finished with what you were working on.
You don’t need to make useless commits though. Instead, you can use the stash command. This command allows you to temporarily set aside all of your changes so that you can come back to them later. In this sense, stash is like setting your book down on the side table (or pushing the cat off your lap) so you can go investigate the noise on the roof. You aren’t putting your book away though, you’re just putting it down for a moment so you can come back and find it exactly the way it was when you put it down.
Let’s say you’ve been working in the branch waiting-for-st-nicholas, and now you need to temporarily set aside your changes to see what the noise was on the roof:
$ git stash
After running this command, all uncommitted work will be temporarily removed from your working directory, and you will be returned to whatever state you were in the last time you committed your work.
With the book safely on the side table, and the cat safely off your lap, you are now free to investigate the noise on the roof. It turns out it’s not reindeer after all, but just your boss who thought they’d help out by writing some code on the project you’ve been working on. Bless. Rolling your eyes, you agree to take a look and see what kind of mischief your boss has gotten themselves into this time.
You fetch an updated list of branches from the remote repository, locate the branch your boss had been working on, and checkout a local copy:
$ git fetch
$ git branch -r
$ git checkout -b helpful-boss-branch origin/helpful-boss-branch
You are now in a local copy of the branch where you are free to look around, and figure out exactly what’s going on.
You sigh audibly and say, ‘Okay. Tell me what was happening when you first realised you’d gotten into a mess’ as you look through the log messages for the branch.
$ git log --oneline
$ git log
By using the log command you will be able to review the history of the branch and find out the moment right before your boss ended up stuck on your roof.
You may also want to compare the work your boss has done to the main branch for your project. For this article, we’ll assume the main branch is named master.
$ git diff master
Looking through the commits, you may be able to see that things started out okay but then took a turn for the worse.
Checking out a single commit
Using commands you’re already familiar with, you can rewind through history and take a look at the state of the code at any moment in time by checking out a single commit, just like you would a branch.
Using the log command, locate the unique identifier (commit hash) of the commit you want to investigate. For example, let’s say the unique identifier you want to checkout is 25f6d7f.
$ git checkout 25f6d7f
Note: checking out '25f6d7f'.
You are in 'detached HEAD' state. You can look around,
make experimental changes and commit them, and you can
discard any commits you make in this state without
impacting any branches by performing another checkout.
If you want to create a new branch to retain commits you create, you may do so (now or later) by using @-b@ with the checkout command again. Example:
$ git checkout -b new_branch_name
HEAD is now at 25f6d7f... Removed first paragraph.
This is usually where people start to panic. Your boss screwed something up, and now your HEAD is detached. Under normal circumstances, these words would be a very good reason to panic.
Take a deep breath. Nothing bad is going to happen. Being in a detached HEAD state just means you’ve temporarily disconnected from a known chain of events. In other words, you’re currently looking at the middle of a story (or branch) about what happened – and you’re not at the endpoint for this particular story.
Git allows you to view the history of your repository as a timeline (technically it’s a directed acyclic graph). When you make commits which are not associated with a branch, they are essentially inaccessible once you return to a known branch. If you make commits while you’re in a detached HEAD state, and then try to return to a known branch, Git will give you a warning and tell you how to save your work.
$ git checkout master
Warning: you are leaving 1 commit behind, not connected to
any of your branches:
7a85788 Your witty holiday commit message.
If you want to keep them by creating a new branch, this may be a good time to do so with:
$ git branch new_branch_name 7a85788
Switched to branch 'master'
Your branch is up-to-date with 'origin/master'.
So, if you want to save the commits you’ve made while in a detached HEAD state, you simply need to put them on a new branch.
$ git branch saved-headless-commits 7a85788
With this trick under your belt, you can jingle around in history as much as you’d like. It’s not like sliding around on a timeline though. When you checkout a specific commit, you will only have access to the history from that point backwards in time. If you want to move forward in history, you’ll need to move back to the branch tip by checking out the branch again.
$ git checkout helpful-boss-branch
You’re now back to the present. Your HEAD is now pointing to the endpoint of a known branch, and so it is no longer detached. Any changes you made while on your adventure are safely stored in a new branch, assuming you’ve followed the instructions Git gave you. That wasn’t so scary after all, now, was it?
Back to our reindeer problem.
If your boss is anything like the bosses I’ve worked with, chances are very good that at least some of their work is worth salvaging. Depending on how your repository is structured, you’ll want to capture the good work using one of several different methods.
Back in the living room, we’ll use our bowl of nuts to illustrate how you can rescue a tiny bit of work.
Saving just one commit
About that bowl of nuts. If you’re like me, you probably had some favourite kinds of nuts from an assorted collection. Walnuts were generally the most satisfying to crack open. So, instead of taking the entire bowl of nuts and dumping it into a stocking (merging the stocking and the bowl of nuts), we’re just going to pick out one nut from the bowl. In Git terms, we’re going to cherry-pick a commit and save it to another branch.
First, checkout the main branch for your development work. From this branch, create a new branch where you can copy the changes into.
$ git checkout master
$ git checkout -b rescue-the-boss
From your boss’s branch, helpful-boss-branch locate the commit you want to keep.
$ git log --oneline helpful-boss-branch
Let’s say the commit ID you want to keep is e08740b. From your rescue branch, use the command cherry-pick to copy the changes into your current branch.
$ git cherry-pick e08740b
If you review the history of your current branch again, you will see you now also have the changes made in the commit in your boss’s branch.
At this point you might need to make a few additional fixes to help your boss out. (You’re angling for a bonus out of all this. Go the extra mile.) Once you’ve made your additional changes, you’ll need to add that work to the branch as well.
$ git add [filename(s)]
$ git commit -m "Building on boss's work to improve feature X."
Go ahead and test everything, and make sure it’s perfect. You don’t want to introduce your own mistakes during the rescue mission!
Uploading the fixed branch
The next step is to upload the new branch to the remote repository so that your boss can download it and give you a huge bonus for helping you fix their branch.
$ git push -u origin rescue-the-boss
Cleaning up and getting back to work
With your boss rescued, and your bonus secured, you can now delete the local temporary branches.
$ git branch --delete rescue-the-boss
$ git branch --delete helpful-boss-branch
And settle back into your chair to wait for Saint Nicholas with your book, your branch, and possibly your cat.
$ git checkout waiting-for-st-nicholas
$ git stash pop
Your working directory has been returned to exactly the same state you were in at the beginning of the article.
Having fun with analogies
I’ve had a bit of fun with analogies in this article. But sometimes those little twists on ideas can really help someone pick up a new idea (git stash: it’s like when Christmas comes around and everyone throws their fashion sense out the window and puts on a reindeer sweater for the holiday party; or git bisect: it’s like trying to find that one broken light on the string of Christmas lights). It doesn’t matter if the analogy isn’t perfect. It’s just a way to give someone a temporary hook into a concept in a way that makes the concept accessible while the learner becomes comfortable with it. As the learner’s comfort increases, the analogies can drop away, making room for the technically correct definition of how something works.
Or, if you’re like me, you can choose to never grow old and just keep mucking about in the analogies. I’d argue it’s a lot more fun to play with a string of Christmas lights and some holiday cheer than a directed acyclic graph anyway. |
2014 |
Emma Jane Westby |
emmajanewestby |
2014-12-02T00:00:00+00:00 |
https://24ways.org/2014/dealing-with-emergencies-in-git/ |
code |
| 246 |
Designing Your Site Like It’s 1998 |
It’s 20 years to the day since my wife and I started Stuff & Nonsense, our little studio and my outlet for creative ideas on the web. To celebrate this anniversary—and my fourteenth contribution to 24 ways— I’d like to explain how I would’ve developed a design for Planes, Trains and Automobiles, one of my favourite Christmas films.
My design for Planes, Trains and Automobiles is fixed at 800px wide.
Developing a <frameset> framework
I’ll start by using frames to set up the framework for this new website. Frames are individual pages—one for navigation, the other for my content—pulled together to form a frameset. Space is limited on lower-resolution screens, so by using frames I can ensure my navigation always remains visible. I can include any number of frames inside a <frameset> element.
I add two rows to my <frameset>; the first is for my navigation and is 50px tall, the second is for my content and will resize to fill any available space. As I don’t want frame borders or any space between my frames, I set frameborder and framespacing attributes to 0:
<frameset frameborder="0" framespacing="0" rows="50,*">
[…]
</frameset>
Next I add the source of my two frame documents. I don’t want people to be able to resize or scroll my navigation, so I add the noresize attribute to that frame:
<frameset frameborder="0" framespacing="0" rows="50,*">
<frame noresize scrolling="no" src="nav.html">
<frame src="content.html">
</frameset>
I do want links from my navigation to open in the content frame, so I give each <frame> a name so I can specify where I want links to open:
<frameset frameborder="0" framespacing="0" rows="50,*">
<frame name="navigation" noresize scrolling="no" src="nav.html">
<frame name="content" src="content.html">
</frameset>
The framework for this website is simple as it contains only two horizontal rows. Should I need a more complex layout, I can nest as many framesets—and as many individual documents—as I need:
<frameset rows="50,*">
<frame name="navigation">
<frameset cols="25%,*">
<frame name="sidebar">
<frame name="content">
</frameset>
</frameset>
Letterbox framesets were common way to deal with multiple screen sizes. In a letterbox, the central frameset had a fixed height and width, while the frames on the top, right, bottom, and left expanded to fill any remaining space.
Handling older browsers
Sadly not every browser supports frames, so I should send a helpful message to people who use older browsers asking them to upgrade. Happily, I can do that using noframes content:
<noframes>
<body>
<p>This page uses frames, but your browser doesn’t support them.
Please upgrade your browser.</p>
</body>
</noframes>
Forcing someone back into a frame
Sometimes, someone may follow a link to a page from a portal or search engine, or they might attempt to open it in a new window or tab. If that page properly belongs inside a <frameset>, people could easily miss out on other parts of a design. This short script will prevent this happening and because it’s vanilla Javascript, it doesn’t require a library such as jQuery:
<script type="text/javascript">
if (top == self) {
location = 'frameset.html';
}
</script>
Laying out my page
Before starting my layout, I add a few basic background and colour styles. I must include these attributes in every page on my website:
<body background="img/container.jpg" bgcolor="#fef7fb"
link="#245eab" alink="#245eab" vlink="#3c146e" text="#000000">
I want absolute control over how people experience my design and don’t want to allow it to stretch, so I first need a <table> which limits the width of my layout to 800px. The align attribute will keep this <table> in the centre of someone’s screen:
<table width="800" align="center">
<tr>
<td>[…]</td>
</tr>
</table>
Although they were developed for displaying tabular information, the cells and rows which make up the <table> element make it ideal for the precise implementation of a design. I need several tables—often nested inside each other—to implement my design. These include tables for a banner and three rows of content:
<table width="800" align="center">
<table>[…]</table>
<table>
<table>
<table>[…]</table>
</table>
</table>
<table>[…]</table>
<table>[…]</table>
</table>
The width of the first table—used for my banner—is fixed to match the logo it contains. As I don’t need borders, padding, or spacing between these cells, I use attributes to remove them:
<table border="0" cellpadding="0" cellspacing="0" width="587" align="center">
<tr>
<td><img src="logo.gif" border="0" width="587" alt="Logo"></td>
</tr>
</table>
The next table—which contains the largest image, introduction, and a call-to-action—is one of the most complex parts of my design, so I need to ensure its layout is pixel perfect. To do that I add an extra row at the top of this table and fill each of its cells with tiny transparent images:
<tr>
<td><img src="spacer.gif" width="593" height="1"></td>
<td><img src="spacer.gif" width="207" height="1"></td>
</tr>
The height and width of these “shims” or “spacers” is only 1px but they will stretch to any size without increasing their weight on the page. This makes them perfect for performant website development.
For the hero of this design, I splice up the large image into three separate files and apply each slice as a background to the table cells. I also match the height of those cells to the background images:
<tr>
<td background="slice-1.jpg" height="473"> </td>
<td background="slice-2.jpg" height="473">[…]</td>
</tr>
<tr>
<td background="slice-3.jpg" height="388"> </td>
</tr>
I use tables and spacer images throughout the rest of this design to lay out the various types of content with perfect precision. For example, to add a single-pixel border around my two columns of content, I first apply a blue background to an outer table along with 1px of cellspacing, then simply nest an inner table—this time with a white background—inside it:
<table border="0" cellpadding="1" cellspacing="0">
<tr>
<td>
<table bgcolor="#ffffff" border="0" cellpadding="0" cellspacing="0">
[…]
</table>
</td>
</tr>
</table>
Adding details
Tables are fabulous tools for laying out a page, but they’re also useful for implementing details on those pages. I can use a table to add a gradient background, rounded corners, and a shadow to the button which forms my “Buy the DVD” call-to-action. First, I splice my button graphic into three slices; two fixed-width rounded ends, plus a narrow gradient which stretches and makes this button responsive. Then, I add those images as backgrounds and use spacers to perfectly size my button:
<table border="0" cellpadding="0" cellspacing="0">
<tr>
<td background="btn-1.jpg" border="0" height="48" width="30"><img src="spacer.gif" width="30" height="1"></td>
<td background="btn-2.jpg" border="0" height="48">
<center>
<a href="" target="_blank"><b>Buy the DVD</b></a>
</center>
</td>
<td background="btn-3.jpg" border="0" height="48" width="30"><img src="spacer.gif" width="30" height="1"></td>
</tr>
</table>
I use those same elements to add details to headlines and lists too. Adding a “bullet” to each item in a list needs only two additional table cells, a circular graphic, and a spacer:
<table border="0" cellpadding="0" cellspacing="0">
<tr>
<td width="10"><img src="li.gif" border="0" width="8" height="8"> </td>
<td><img src="spacer.gif" width="10" height="1"> </td>
<td>Directed by John Hughes</td>
</tr>
</table>
Implementing a typographic hierarchy
So far I’ve explained how to use frames, tables, and spacers to develop a layout for my content, but what about styling that content? I use <font> elements to change the typeface from the browser’s default to any font installed on someone’s device:
<font face="Arial">Planes, Trains and Automobiles is a comedy film […]</font>
To adjust the size of those fonts, I use the size attribute and a value between the smallest (1) and the largest (7) where 3 is the browser’s default. I use a size of 4 for this headline and 2 for the text which follows:
<font face="Arial" size="4"><b>Steve Martin</b></font>
<font face="Arial" size="2">An American actor, comedian, writer, producer, and musician.</font>
When I need to change the typeface, perhaps from a sans-serif like Arial to a serif like Times New Roman, I must change the value of the face attribute on every element on all pages on my website.
NB: I use as many <br> elements as needed to create space between headlines and paragraphs.
View the final result (and especially the source.)
My modern day design for Planes, Trains and Automobiles.
I can imagine many people reading this and thinking “This is terrible advice because we don’t develop websites like this in 2018.” That’s true.
We have the ability to embed any number of web fonts into our products and websites and have far more control over type features, leading, ligatures, and sizes:
font-variant-caps: titling-caps;
font-variant-ligatures: common-ligatures;
font-variant-numeric: oldstyle-nums;
Grid has simplified the implementation of even the most complex compound grid down to just a few lines of CSS:
body {
display: grid;
grid-template-columns: 3fr 1fr 2fr 2fr 1fr 3fr;
grid-template-rows: auto;
grid-column-gap: 2vw;
grid-row-gap: 1vh;
}
Flexbox has made it easy to develop flexible components such as navigation links:
nav ul { display: flex; }
nav li { flex: 1; }
Just one line of CSS can create multiple columns of fluid type:
main { column-width: 12em; }
CSS Shapes enable text to flow around irregular shapes including polygons:
[src*="main-img"] {
float: left;
shape-outside: polygon(…);
}
Today, we wouldn’t dream of using images and a table to add a gradient, rounded corners, and a shadow to a button or link, preferring instead:
.btn {
background: linear-gradient(#8B1212, #DD3A3C);
border-radius: 1em;
box-shadow: 0 2px 4px 0 rgba(0,0,0,0.50), inset 0 -1px 1px 0 rgba(0,0,0,0.50);
}
CSS Custom Properties, feature and media queries, filters, pseudo-elements, and SVG; the list of advances in HTML, CSS, and other technologies goes on. So does our understanding of how best to use them by separating content, structure, presentation, and behaviour. As 2018 draws to a close, we’re certain we know how to design and develop products and websites better than we did at the end of 1998.
Strange as it might seem looking back, in 1998 we were also certain our techniques and technologies were the best for the job. That’s why it’s dangerous to believe with absolute certainty that the frameworks and tools we increasingly rely on today—tools like Bootstrap, Bower, and Brunch, Grunt, Gulp, Node, Require, React, and Sass—will be any more relevant in the future than <font> elements, frames, layout tables, and spacer images are today.
I have no prediction for what the web will be like twenty years from now. However, I want to believe we’ll build on what we’ve learned during these past two decades about the importance of accessibility, flexibility, and usability, and that the mistakes we made while infatuated by technologies won’t be repeated.
Head over to my website if you’d like to read about how I’d implement my design for ‘Planes, Trains and Automobiles’ today. |
2018 |
Andy Clarke |
andyclarke |
2018-12-23T00:00:00+00:00 |
https://24ways.org/2018/designing-your-site-like-its-1998/ |
code |
| 256 |
Develop Your Naturalist Superpowers with Observable Notebooks and iNaturalist |
We’re going to level up your knowledge of what animals you might see in an area at a particular time of year - a skill every naturalist* strives for - using technology! Using iNaturalist and Observable Notebooks we’re going to prototype seasonality graphs for particular species in an area, and automatically create a guide to what animals you might see in each month.
*(a Naturalist is someone who likes learning about nature, not someone who’s a fan of being naked, that’s a ‘Naturist’… different thing!)
Looking for critters in rocky intertidal habitats
One of my favourite things to do is going rockpooling, or as we call it over here in California, ‘tidepooling’. Amounting to the same thing, it’s going to a beach that has rocks where the tide covers then uncovers little pools of water at different times of the day. All sorts of fun creatures and life can be found in this ‘rocky intertidal habitat’
A particularly exciting creature that lives here is the Nudibranch, a type of super colourful ‘sea slug’. There are over 3000 species of Nudibranch worldwide. (The word “nudibranch” comes from the Latin nudus, naked, and the Greek βρανχια / brankhia, gills.)
They are however quite tricky to find! Even though they are often brightly coloured and interestingly shaped, some of them are very small, and in our part of the world in the Bay Area in California their appearance in our rockpools is seasonal. We see them more often in Summer months, despite the not-as-low tides as in our Winter and Spring seasons.
My favourite place to go tidepooling here is Pillar Point in Half Moon bay (at other times of the year more famously known for the surf competition ‘Mavericks’). The rockpools there are rich in species diversity, of varied types and water-coverage habitat zones as well as being relatively accessible.
I was rockpooling at Pillar Point recently with my parents and we talked to a lady who remarked that she hadn’t seen any Nudibranchs on her visit this time. I realised that having an idea of what species to find where, and at what time of year is one of the many superpower goals of every budding Naturalist.
Using technology and the croudsourced species observations of the iNaturalist community we can shortcut our way to this superpower!
Finding nearby animals with iNaturalist
We’re going to be getting our information about what animals you can see in Pillar Point using iNaturalist. iNaturalist is a really fun platform that helps connect people to nature and report their findings of life in the outdoors. It is also a community of nature-loving people who help each other identify and confirm those observations. iNaturalist is a project run as a joint initiative by the California Academy of Sciences and the National Geographic Society.
I’ve been using iNaturalist for over two years to record and identify plants and animals that I’ve found in the outdoors. I use their iPhone app to upload my pictures, which then uses machine learning algorithms to make an initial guess at what it is I’ve seen. The community is really active, and I often find someone else has verified or updated my species guess pretty soon after posting.
This process is great because once an observation has been identified by at least two people it becomes ‘verified’ and is considered research grade. Research grade observations get exported and used by scientists, as well as being indexed by the Global Biodiversity Information Facility, GBIF.
iNaturalist has a great API and API explorer, which makes interacting and prototyping using iNaturalist data really fun. For example, if you go to the API explorer and expand the Observations : Search and fetch section and then the GET /observations API, you get a selection of input boxes that allow you to play with options that you can then pass to the API when you click the ‘Try it out’ button.
You’ll then get a URL that looks a bit like
https://api.inaturalist.org/v1/observations?captive=false &geo=true&verifiable=true&taxon_id=47113&lat=37.495461&lng=-122.499584 &radius=5&order=desc&order_by=created_at
which you can call and interrrogate using a programming language of your choice.
If you would like to see an all-JavaScript application that uses the iNaturalist API, take a look at OwlsNearMe.com which Simon and I built one weekend earlier this year. It gets your location and shows you all iNaturalist observations of owls near you and lists which species you are likely to see (not adjusted for season).
Rapid development using Observable Notebooks
We’re going to be using Observable Notebooks to prototype our examples, pulling data down from iNaturalist. I really like using visual notebooks like Observable, they are great for learning and building things quickly. You may be familiar with Jupyter notebooks for Python which is similar but takes a bit of setup to get going - I often use these for prototyping too. Observable is amazing for querying and visualising data with JavaScript and since it is a hosted product it doesn’t require any setup at all.
You can follow along and play with this example on my Observable notebook. If you create an account there you can fork my notebook and create your own version of this example.
Each ‘notebook’ consists of a page with a column of ‘cells’, similar to what you get in a spreadsheet. A cell can contain Markdown text or JavaScript code and the output of evaluating the cell appears above the code that generated it. There are lots of tutorials out there on Observable Notebooks, I like this code introduction one from Observable (and D3) creator Mike Bostock.
Developing your Naturalist superpowers
If you have an idea of what plants and critters you might see in a place at the time you visit, you can hone in on what you want to study and train your Naturalist eye to better identify the life around you.
For our example, we care about wildlife we can see at Pillar Point, so we need a way of letting the iNaturalist API know which area we are interested in.
We could use a latitide, longitude and radius for this, but a rectangular bounding box is a better shape for the reef. We can use this tool to draw the area we want to search within: boundingbox.klokantech.com
The tool lets you export the bounding box in several forms using the dropdown at the bottom left under the map givese We are going to use the ‘DublinCore’ format as it’s closest to the format needed by the iNaturalist API.
westlimit=-122.50542; southlimit=37.492805; eastlimit=-122.492738; northlimit=37.499811
A quick map primer:
The higher the latitude the more north it is
The lower the latitude the more south it is
Latitude 0 = the equator
The higher the longitude the more east it is of Greenwich
The lower the longitude the more west it is of Greenwich
Longitude 0 = Greenwich
In the iNaturalst API we want to use the parameters nelat, nelng, swlat, swlng to create a query that looks inside a bounding box of Pillar Point near Half Moon Bay in California:
nelat = highest latitude = north limit = 37.499811
nelng = highest longitude = east limit = -122.492738
swlat = smallest latitude = south limit = 37.492805
swlng = smallest longitude = west limit = 122.50542
As API parameters these look like this:
?nelat=37.499811&nelng=-122.492738&swlat=37.492805&swlng=122.50542
These parameters in this format can be used for most of the iNaturalist API methods.
Nudibranch seasonality in Pillar Point
We can use the iNaturalist observation_histogram API to get a count of Nudibranch observations per week-of-year across all time and within our Pillar Point bounding box.
In addition to the geographic parameters that we just worked out, we are also sending the taxon_id of 47113, which is iNaturalists internal number associated with the Nudibranch taxon. By using this we can get all species which are under the parent ‘Order Nudibranchia’.
Another useful piece of naturalist knowledge is understanding the biological classification scheme of Taxanomic Rank - roughly, when a species has a Latin name of two words eg ‘Glaucus Atlanticus’ the first Latin word is the ‘Genus’ like a family name ‘Glaucus’, and the second word identifies that particular species, like a given name ‘Atlanticus’.
The two Latin words together indicate a specific species, the term we use colloquially to refer to a type of animal often differs wildly region to region, and sometimes the same common name in two countries can refer to two different species. The common names for the Glaucus Atlanticus (which incidentally is my favourite sea slug) include: sea swallow, blue angel, blue glaucus, blue dragon, blue sea slug and blue ocean slug! Because this gets super confusing, Scientists like using this Latin name format instead.
The following piece of code asks the iNaturalist Histogram API to return per-week counts for verified observations of Nudibranchs within our Pillar Point bounding box:
pillar_point_counts_per_week = fetch(
"https://api.inaturalist.org/v1/observations/histogram?taxon_id=47113&nelat=37.499811&nelng=-122.492738&swlat=37.492805&swlng=-122.50542&date_field=observed&interval=week_of_year&verifiable=true"
).then(response => {
return response.json();
})
Our next step is to take this data and draw a graph! We’ll be using Vega-Lite for this, which is a fab JavaScript graphing libary that is also easy and fun to use with Observable Notebooks.
(Here is a great tutorial on exploring data and drawing graphs with Observable and Vega-Lite)
The iNaturalist API returns data that looks like this:
{
"total_results": 53,
"page": 1,
"per_page": 53,
"results": {
"week_of_year": {
"1": 136,
"2": 20,
"3": 150,
"4": 65,
"5": 186,
"6": 74,
"7": 47,
"8": 87,
"9": 64,
"10": 56,
But for our Vega-Lite graph we need data that looks like this:
[{
"week": "01",
"value": 136
}, {
"week": "02",
"value": 20
}, ...]
We can convert what we get back from the API to the second format using a loop that iterates over the object keys:
objects_to_plot = {
let objects = [];
Object.keys(pillar_point_counts_per_week.results.week_of_year).map(function(week_index) {
objects.push({
week: `Wk ${week_index.toString()}`,
observations: pillar_point_counts_per_week.results.week_of_year[week_index]
});
})
return objects;
}
We can then plug this into Vega-Lite to draw us a graph:
vegalite({
data: {values: objects_to_plot},
mark: "bar",
encoding: {
x: {field: "week", type: "nominal", sort: null},
y: {field: "observations", type: "quantitative"}
},
width: width * 0.9
})
It’s worth noting that we have a lot of observations of Nudibranchs particularly at Pillar Point due in no small part to the intertidal monitoring research that Alison Young and Rebecca Johnson facilitate for the California Achademy of Sciences.
So, what if we want to look for the seasonality of observations of a particular species of adorable sea slug? We want our interface to have a select box with a list of all the species you might find at any time of year. We can do this using the species_counts API to create us an object with the iNaturalist species ID and common & Latin names.
pillar_point_nudibranches = {
let api_results = await fetch(
"https://api.inaturalist.org/v1/observations/species_counts?taxon_id=47113&nelat=37.499811&nelng=-122.492738&swlat=37.492805&swlng=-122.50542&date_field=observed&verifiable=true"
).then(r => r.json())
let species_list = api_results.results.map(i => ({
value: i.taxon.id,
label: `${i.taxon.preferred_common_name} (${i.taxon.name})`
}));
return species_list
}
We can create an interactive select box by importing code from Jeremy Ashkanas’ Observable Notebook: add import {select} from "@jashkenas/inputs" to a cell anywhere in our notebook. Observable is magic: like a spreadsheet, the order of the cells doesn’t matter - if one cell is referenced by any other cell then when that cell updates all the other cells refresh themselves. You can also import and reference one notebook from another!
viewof select_species = select({
title: "Which Nudibranch do you want to see seasonality for?",
options: [{value: "", label: "All the Nudibranchs!"}, ...pillar_point_nudibranches],
value: ""
})
Then we go back to our old favourite, the histogram API just like before, only this time we are calling it with the value created by our select box ${select_species} as taxon_id instead of the number 47113.
pillar_point_counts_per_month_per_species = fetch(
`https://api.inaturalist.org/v1/observations/histogram?taxon_id=${select_species}&nelat=37.499811&nelng=-122.492738&swlat=37.492805&swlng=-122.50542&date_field=observed&interval=month_of_year&verifiable=true`
).then(r => r.json())
Now for the fun graph bit! As we did before, we re-format the result of the API into a format compatible with Vega-Lite:
objects_to_plot_species_month = {
let objects = [];
Object.keys(pillar_point_counts_per_month_per_species.results.month_of_year).map(function(month_index) {
objects.push({
month: (new Date(2018, (month_index - 1), 1)).toLocaleString("en", {month: "long"}),
observations: pillar_point_counts_per_month_per_species.results.month_of_year[month_index]
});
})
return objects;
}
(Note that in the above code we are creating a date object with our specific month in, and using toLocalString() to get the longer English name for the month. Because the JavaScript Date object counts January as 0, we use month_index -1 to get the correct month)
And we draw the graph as we did before, only now if you interact with the select box in Observable the graph will dynamically update!
vegalite({
data: {values: objects_to_plot_species_month},
mark: "bar",
encoding: {
x: {field: "month", type: "nominal", sort:null},
y: {field: "observations", type: "quantitative"}
},
width: width * 0.9
})
Now we can see when is the best time of year to plan to go tidepooling in Pillar Point if we want to find a specific species of Nudibranch.
This tool is great for planning when we to go rockpooling at Pillar Point, but what about if you are going this month and want to pre-train your eye with what to look for in order to impress your friends with your knowledge of Nudibranchs?
Well… we can create ourselves a dynamic guide that you can with a list of the species, their photo, name and how many times they have been observed in that month of the year!
Our select box this time looks as follows, simpler than before but assigning the month value to the variable selected_month.
viewof selected_month = select({
title: "When do you want to see Nudibranchs?",
options: [
{ label: "Whenever", value: "" },
{ label: "January", value: "1" },
{ label: "February", value: "2" },
{ label: "March", value: "3" },
{ label: "April", value: "4" },
{ label: "May", value: "5" },
{ label: "June", value: "6" },
{ label: "July", value: "7" },
{ label: "August", value: "8" },
{ label: "September", value: "9" },
{ label: "October", value: "10" },
{ label: "November", value: "11" },
{ label: "December", value: "12" },
],
value: ""
})
We then can use the species_counts API to get all the relevant information about which species we can see in month=${selected_month}. We’ll be able to reference this response object and its values later with the variable we just created, eg: all_species_data.results[0].taxon.name.
all_species_data = fetch(
`https://api.inaturalist.org/v1/observations/species_counts?taxon_id=47113&month=${selected_month}&nelat=37.499811&nelng=-122.492738&swlat=37.492805&swlng=-122.50542&verifiable=true`
).then(r => r.json())
You can render HTML directly in a notebook cell using Observable’s html tagged template literal:
<style>
.collection { margin-top: 2em }
.collection .species { display: inline-block; width: 9em; margin-bottom: 2em; }
.collection .species-name { font-size: 1em; margin: 0; padding: 0 }
.collection .species-count { margin: 0 0 0.3em 0; padding: 0; font-size: 0.75em; color: #999; font-style: italic; }
.collection img { display: block; width: 100% }
.collection select { font-size: 1.5em; }
</style>
<h2>If you go to Pillar Point ${
{"": "",
"1":"in January",
"2":"in Febrary",
"3":"in March",
"4":"in April",
"5":"in May",
"6":"in June",
"7":"in July",
"8":"in August",
"9":"in September",
"10":"in October",
"11":"in November",
"12":"in December",
}[selected_month]
} you might see…</h2>
<div class="collection">
${all_species_data.results.map(s => `<div class="species"><h3 class="species-name">${s.taxon.name}</h3>
<p class="species-count">Seen ${s.count} times</p>
<img src="${s.taxon.default_photo.medium_url}"></div>
`)}
</div>
These few lines of HTML are all you need to get this exciting dynamic guide to what Nudibranchs you will see in each month!
Play with it yourself in this Observable Notebook.
Conclusion
I hope by playing with these examples you have an idea of how powerful it can be to prototype using Observable Notebooks and how you can use the incredible crowdsourced community data and APIs from iNaturalist to augment your naturalist skills and impress your friends with your new ‘knowledge of nature’ superpower.
Lastly I strongly encourage you to get outside on a low tide to explore your local rocky intertidal habitat, and all the amazing critters that live there.
Here is a great introduction video to tidepooling / rockpooling, by Rebecca Johnson and Alison Young from the California Academy of Sciences. |
2018 |
Natalie Downe |
nataliedowne |
2018-12-18T00:00:00+00:00 |
https://24ways.org/2018/observable-notebooks-and-inaturalist/ |
code |
| 89 |
Direction, Distance and Destinations |
With all these new smartphones in the hands of lost and confused owners, we need a better way to represent distances and directions to destinations. The immediate examples that jump to mind are augmented reality apps which let you see another world through your phone’s camera. While this is interesting, there is a simpler way: letting people know how far away they are and if they are getting warmer or colder.
In the app world, you can easily tap into the phone’s array of sensors such as the GPS and compass, but what people rarely know is that you can do the same with HTML. The native versus web app debate will never subside, but at least we can show you how to replicate some of the functionality progressively in HTML and JavaScript.
In this tutorial, we’ll walk through how to create a simple webpage listing distances and directions of a few popular locations around the world. We’ll use JavaScript to access the device’s geolocation API and also attempt to access the compass to get a heading. Both of these APIs are documented, to be included in the W3C geolocation API specification, and can be used on both desktop and mobile devices today.
To get started, we need a list of a few locations around the world. I have chosen the highest mountain peak on each continent so you can see a diverse set of distances and directions.
Mountain
°Latitude
°Longitude
Kilimanjaro
-3.075833
37.353333
Vinson Massif
-78.525483
-85.617147
Puncak Jaya
-4.078889
137.158333
Everest
27.988056
86.925278
Elbrus
43.355
42.439167
Mount McKinley
63.0695
-151.0074
Aconcagua
-32.653431
-70.011083
Source: Wikipedia
We can put those into an HTML list to be styled and accessed by JavaScript to create some distance and directions calculations.
The next thing we need to do is check to see if the browser and operating system have geolocation support. To do this we test to see if the function is available or not using a single JavaScript if statement.
<script>
// If this is true, then the method is supported and we can try to access the location
if (navigator.geolocation) {
navigator.geolocation.getCurrentPosition(geo_success, geo_error);
}
</script>
The if statement will be false if geolocation support is not present, and then it is up to you to do something else instead as a fallback. For this example, we’ll do nothing since our page should work as is and only get progressively better if more functionality is available.
The if statement will be true if there is support and therefore will continue inside the curly brackets to try to get the location. This should prompt the reader to accept or deny the request to get their location. If they say no, the second function callback is processed, in this case a function called geo_error; whereas if the location is available, it fires the geo_success function callback.
The function geo_error(){ } isn’t that exciting. You can handle this in any way you see fit. The success function is more interesting. We get a position object passed into the function which contains a series of exciting attributes, namely the latitude and longitude of the device’s current location.
function geo_success(position){
gLat = position.coords.latitude;
gLon = position.coords.longitude;
}
Now, in the variables gLat and gLon we have the user’s approximate geographical position. We can use this information to start to calculate some distances between where they are and all the destinations.
At the time of writing, you can also get position.coords.heading, but on Windows and iOS devices this returned NULL. In the future, if and when this is supported, this is also where you can easily grab the compass information.
Inside the geo_success function, we want to loop through the HTML to get all of the mountain peaks’ latitudes and longitudes and compute the distance.
...
$('.geo').each(function(){
// Get the lat/lon from the HTML
tLat = $(this).find('.lat').html()
tLon = $(this).find('.lon').html()
// compute the distances between the current location and this points location
dist = distance(tLat,tLon,gLat,gLon);
// set the return values into something useful
d = parseInt(dist[0]*10)/10;
a = parseFloat(dist[1]);
// display the value in the HTML and style the arrow
$(this).find('.distance').html(d+' km away');
$(this).find('.direction').css('-webkit-transform','rotate(-' + a + 'deg)');
// store the arc for later use if compass is available
$(this).attr('data-arc',a);
}
In the variable d we have the distance between the current location and the location of the mountain peak based on the Haversine Formula. The variable a is the arc, which has a value from 0 to 359.99. This will be useful later if we have compass support. Given these two values we have a distance and a heading to style the HTML.
The next thing we want to do is check to see if the device has a compass and then get access to the the current heading. As we’ll see, there are several ways to do this, some of which work on certain devices but not others. The W3C geolocation spec says that, along with the coordinates, there are several other attributes: accuracy; altitude; and heading. Heading is the direction to true north, which is different than magnetic north! WebKit and Windows return NULL for the heading value, but WebKit has an experimental method to fetch the heading. If you get into accessing these sensors, you’ll have to try to catch a few of these methods to finally get a value. Assuming you do, we can move on to the more interesting display opportunities.
In an ideal world, this would succeed and set a variable we’ll call compassHeading to get a value between 0 and 359.99 degrees. Now we know which direction north is, we also know the direction relative to north of the path to our destination, so we can can subtract the two values to get an arrow to display on the screen. But we’re not finished yet: we also need to get the device’s orientation (landscape or portrait) and subtract the correct amount from the angle for the arrow. Once we have a value, we can use CSS to rotate the arrow the correct number of degrees.
-webkit-transform: rotate(-180deg)
Not all devices support a standard way to access compass information, so in the meantime we need to use a work around. On iOS, you can use the experimental event method e.webkitCompassHeading. We want the compass to update in real time as the device is moved around, so we’ll put this inside an event listener.
window.addEventListener('deviceorientation', function(e) {
// Loop through all the locations on the page
$('.geo').each(function(){
// get the arc value from north we computed and stored earlier
destination_arc = parseInt($(this).attr('data-arc'))
compassHeading = e.webkitCompassHeading + window.orientation + destination_arc;
// find the arrow element and rotate it accordingly
$(this).find('.direction').css('-webkit-transform','rotate(-' + compassHeading + 'deg)');
}
}
As the device is rotated, the compass arrow will constantly be updated. If you want to see an example, you can have a look at this page which shows the distances to all the peaks on each continent.
With progressive enhancement, we slowly layer on additional functionality as we go. The reader will first see the list of locations with a latitude and longitude. If the device is capable and permissions allow, it will then compute the distance. If a compass is available, with the correct permissions it will then add the final layer which is direction.
You should consider this code a stub for your projects. If you are making a hyperlocal webpage with restaurant locations, for example, then consider adding these features. Knowing not only how far away a place is, but also the direction can be hugely important, and since the compass is always active, it acts as a guide to the location.
Future developments
Improvements to this could include setting a timer and recalling the navigator.geolocation.getCurrentPosition() function and updating the distances. I chose very distant mountains so kilometres made sense, but you can divide again by 1,000 to convert to metres if you are dealing with much nearer places. Walking or driving would change the distances so the ability to refresh would be important.
It is outside the scope of this article, but if you manage to get this HTML to work offline, then you can make a nice web app which sits on your devices’ homescreens and works even without an internet connection. This could be ideal for travellers in an unknown city looking for your destination. Just with offline storage, base64 encoding and data URIs, it is possible to embed plenty of design and functionality into a small offline webpage.
Now you know how to use JavaScript to look up a destination’s location and figure out the distance and direction – never get lost again. |
2012 |
Brian Suda |
briansuda |
2012-12-19T00:00:00+00:00 |
https://24ways.org/2012/direction-distance-and-destinations/ |
code |
| 288 |
Displaying Icons with Fonts and Data- Attributes |
Traditionally, bitmap formats such as PNG have been the standard way of delivering iconography on websites. They’re quick and easy, and it also ensures they’re as pixel crisp as possible. Bitmaps have two drawbacks, however: multiple HTTP requests, affecting the page’s loading performance; and a lack of scalability, noticeable when the page is zoomed or viewed on a screen with a high pixel density, such as the iPhone 4 and 4S.
The requests problem is normally solved by using CSS sprites, combining the icon set into one (physically) large image file and showing the relevant portion via background-position. While this works well, it can get a bit fiddly to specify all the positions. In particular, scalability is still an issue. A vector-based format such as SVG sounds ideal to solve this, but browser support is still patchy.
The rise and adoption of web fonts have given us another alternative. By their very nature, they’re not only scalable, but resolution-independent too. No need to specify higher resolution graphics for high resolution screens!
That’s not all though:
Browser support: Unlike a lot of new shiny techniques, they have been supported by Internet Explorer since version 4, and, of course, by all modern browsers. We do need several different formats, however!
Design on the fly: The font contains the basic graphic, which can then be coloured easily with CSS – changing colours for themes or :hover and :focus styles is done with one line of CSS, rather than requiring a new graphic. You can also use CSS3 properties such as text-shadow to add further effects. Using -webkit-background-clip: text;, it’s possible to use gradient and inset shadow effects, although this creates a bitmap mask which spoils the scalability.
Small file size: specially designed icon fonts, such as Drew Wilson’s Pictos font, can be as little as 12Kb for the .woff font. This is because they contain fewer characters than a fully fledged font. You can see Pictos being used in the wild on sites like Garrett Murray’s Maniacal Rage.
As with all formats though, it’s not without its disadvantages:
Icons can only be rendered in monochrome or with a gradient fill in browsers that are capable of rendering CSS3 gradients. Specific parts of the icon can’t be a different colour.
It’s only appropriate when there is an accompanying text to provide meaning. This can be alleviated by wrapping the text label in a tag (I like to use <b> rather than <span>, due to the fact that it’s smaller and isn’ t being used elsewhere) and then hiding it from view with text-indent:-999em.
Creating an icon font can be a complex and time-consuming process. While font editors can carry out hinting automatically, the best results are achieved manually.
Unless you’re adept at creating your own fonts, you’re restricted to what is available in the font. However, fonts like Pictos will cover the most common needs, and icons are most effective when they’re using familiar conventions.
The main complaint about using fonts for icons is that it can mean adding a meaningless character to our markup. The good news is that we can overcome this by using one of two methods – CSS generated content or the data-icon attribute – in combination with the :before and :after pseudo-selectors, to keep our markup minimal and meaningful.
Our simple markup looks like this:
<a href="/basket" class="icon basket">View Basket</a>
Note the multiple class attributes. Next, we’ll import the Pictos font using the @font-face web fonts property in CSS:
@font-face {
font-family: 'Pictos';
src: url('pictos-web.eot');
src: local('☺'),
url('pictos-web.woff') format('woff'),
url('pictos-web.ttf') format('truetype'),
url('pictos-web.svg#webfontIyfZbseF') format('svg');
}
This rather complicated looking set of rules is (at the time of writing) the most bulletproof way of ensuring as many browsers as possible load the font we want. We’ll now use the content property applied to the :before pseudo-class selector to generate our icon. Once again, we’ll use those multiple class attribute values to set common icon styles, then specific styles for .basket. This helps us avoid repeating styles:
.icon {
font-family: 'Pictos';
font-size: 22px:
}
.basket:before {
content: "$";
}
What does the :before pseudo-class do? It generates the dollar character in a browser, even when it’s not present in the markup. Using the generated content approach means our markup stays simple, but we’ll need a new line of CSS, defining what letter to apply to each class attribute for every icon we add.
data-icon is a new alternative approach that uses the HTML5 data- attribute in combination with CSS attribute selectors. This new attribute lets us add our own metadata to elements, as long as its prefixed by data- and doesn’t contain any uppercase letters. In this case, we want to use it to provide the letter value for the icon. Look closely at this markup and you’ll see the data-icon attribute.
<a href="/basket" class="icon" data-icon="$">View Basket</a>
We could add others, in fact as many as we like.
<a href="/" class="icon" data-icon="k">Favourites</a>
<a href="/" class="icon" data-icon="t">History</a>
<a href="/" class="icon" data-icon="@">Location</a>
Then, we need just one CSS attribute selector to style all our icons in one go:
.icon:before {
content: attr(data-icon);
/* Insert your fancy colours here */
}
By placing our custom attribute data-icon in the selector in this way, we can enable CSS to read the value of that attribute and display it before the element (in this case, the anchor tag). It saves writing a lot of CSS rules. I can imagine that some may not like the extra attribute, but it does keep it out of the actual content – generated or not.
This could be used for all manner of tasks, including a media player and large simple illustrations. See the demo for live examples. Go ahead and zoom the page, and the icons will be crisp, with the exception of the examples that use -webkit-background-clip: text as mentioned earlier.
Finally, it’s worth pointing out that with both generated content and the data-icon method, the letter will be announced to people using screen readers. For example, with the shopping basket icon above, the reader will say “dollar sign view basket”. As accessibility issues go, it’s not exactly the worst, but could be confusing. You would need to decide whether this method is appropriate for the audience. Despite the disadvantages, icon fonts have huge potential. |
2011 |
Jon Hicks |
jonhicks |
2011-12-12T00:00:00+00:00 |
https://24ways.org/2011/displaying-icons-with-fonts-and-data-attributes/ |
code |
| 188 |
Don't Lose Your :focus |
For many web designers, accessibility conjures up images of blind users with screenreaders, and the difficulties in making sites accessible to this particular audience. Of course, accessibility covers a wide range of situations that go beyond the extreme example of screenreader users. And while it’s true that making a complex site accessible can often be a daunting prospect, there are also many small things that don’t take anything more than a bit of judicious planning, are very easy to test (without having to buy expensive assistive technology), and can make all the difference to certain user groups.
In this short article we’ll focus on keyboard accessibility and how careless use of CSS can potentially make your sites completely unusable.
Keyboard Access
Users who for whatever reason can’t use a mouse will employ a keyboard (or keyboard-like custom interface) to navigate around web pages. By default, they will use TAB and SHIFT + TAB to move from one focusable element (links, form controls and area) of a page to the next.
Note: in OS X, you’ll first need to turn on full keyboard access under System Preferences > Keyboard and Mouse > Keyboard Shortcuts. Safari under Windows needs to have the option Press Tab to highlight each item on a webpage in Preferences > Advanced enabled. Opera is the odd one out, as it has a variety of keyboard navigation options – the most relevant here being spatial navigation via Shift+Down, Shift+Up, Shift+Left, and Shift+Right).
But I Don’t Like Your Dotted Lines…
To show users where they are within a page, browsers place an outline around the element that currently has focus. The “problem” with these default outlines is that some browsers (Internet Explorer and Firefox) also display them when a user clicks on a focusable element with the mouse. Particularly on sites that make extensive use of image replacement on links with “off left” techniques this can create very unsightly outlines that stretch from the replaced element all the way to the left edge of the browser.
Outline bleeding off to the left (image-replacement example from carsonified.com)
There is a trivial workaround to prevent outlines from “spilling over” by adding a simple overflow:hidden, which keeps the outline in check around the clickable portion of the image-replaced element itself.
Outline tamed with overflow:hidden
But for many designers, even this is not enough. As a final solution, many actively suppress outlines altogether in their stylesheets. Controversially, even Eric Meyer’s popular reset.css – an otherwise excellent set of styles that levels the playing field of varying browser defaults – suppresses outlines.
html, body, div, span, applet, object, iframe ... {
...
outline: 0;
...
}
/* remember to define focus styles! */
:focus {
outline: 0;
}
Yes, in his explanation (and in the CSS itself) Eric does remind designers to define relevant styles for :focus… but judging by the number of sites that seem to ignore this (and often remove the related comment from the stylesheet altogether), the message doesn’t seem to have sunk in.
Anyway… hurrah! No more unsightly dotted lines on our lovely design. But what about keyboard users? Although technically they can still TAB from one element to the next, they now get no default cue as to where they are within the page (one notable exception here is Opera, where the outline is displayed regardless of stylesheets)… and if they’re Safari users, they won’t even get an indication of a link’s target in the status bar, like they would if they hovered over it with the mouse.
Only Suppress outline For Mouse Users
Is there a way to allow users navigating with the keyboard to retain the standard outline behaviour they’ve come to expect from their browser, while also ensuring that it doesn’t show display for mouse users?
Testing some convoluted style combinations
After playing with various approaches (see Better CSS outline suppression for more details), the most elegant solution also seemed to be the simplest: don’t remove the outline on :focus, do it on :active instead – after all, :active is the dynamic pseudo-class that deals explicitly with the styles that should be applied when a focusable element is clicked or otherwise activated.
a:active { outline: none; }
The only minor issues with this method: if a user activates a link and then uses the browser’s back button, the outline becomes visible. Oh, and old versions of Internet Explorer notoriously get confused by the exact meaning of :focus, :hover and :active, so this method fails in IE6 and below. Personally, I can live with both of these.
Note: at the last minute before submitting this article, I discovered a fatal flaw in my test. It appears that outline still manages to appear in the time between activating a link and the link target loading (which in hindsight is logical – after activation, the link does indeed receive focus). As my test page only used in-page links, this issue never came up before. The slightly less elegant solution is to also suppress the outline on :hover.
a:hover, a:active { outline: none; }
In Conclusion
Of course, many web designers may argue that they know what’s best, even for their keyboard-using audience. Maybe they’ve removed the default outline and are instead providing some carefully designed :focus styles. If they know for sure that these custom styles are indeed a reliable alternative for their users, more power to them… but, at the risk of sounding like Jakob “blue underlined links” Nielsen, I’d still argue that sometimes the default browser behaviours are best left alone. Complemented, yes (and if you’re already defining some fancy styles for :hover, by all means feel free to also make them display on :focus)… but not suppressed. |
2009 |
Patrick Lauke |
patricklauke |
2009-12-09T00:00:00+00:00 |
https://24ways.org/2009/dont-lose-your-focus/ |
code |
| 326 |
Don't be eval() |
JavaScript is an interpreted language, and like so many of its peers it includes the all powerful eval() function. eval() takes a string and executes it as if it were regular JavaScript code. It’s incredibly powerful and incredibly easy to abuse in ways that make your code slower and harder to maintain. As a general rule, if you’re using eval() there’s probably something wrong with your design.
Common mistakes
Here’s the classic misuse of eval(). You have a JavaScript object, foo, and you want to access a property on it – but you don’t know the name of the property until runtime. Here’s how NOT to do it:
var property = 'bar';
var value = eval('foo.' + property);
Yes it will work, but every time that piece of code runs JavaScript will have to kick back in to interpreter mode, slowing down your app. It’s also dirt ugly.
Here’s the right way of doing the above:
var property = 'bar';
var value = foo[property];
In JavaScript, square brackets act as an alternative to lookups using a dot. The only difference is that square bracket syntax expects a string.
Security issues
In any programming language you should be extremely cautious of executing code from an untrusted source. The same is true for JavaScript – you should be extremely cautious of running eval() against any code that may have been tampered with – for example, strings taken from the page query string. Executing untrusted code can leave you vulnerable to cross-site scripting attacks.
What’s it good for?
Some programmers say that eval() is B.A.D. – Broken As Designed – and should be removed from the language. However, there are some places in which it can dramatically simplify your code. A great example is for use with XMLHttpRequest, a component of the set of tools more popularly known as Ajax. XMLHttpRequest lets you make a call back to the server from JavaScript without refreshing the whole page. A simple way of using this is to have the server return JavaScript code which is then passed to eval(). Here is a simple function for doing exactly that – it takes the URL to some JavaScript code (or a server-side script that produces JavaScript) and loads and executes that code using XMLHttpRequest and eval().
function evalRequest(url) {
var xmlhttp = new XMLHttpRequest();
xmlhttp.onreadystatechange = function() {
if (xmlhttp.readyState==4 && xmlhttp.status==200) {
eval(xmlhttp.responseText);
}
}
xmlhttp.open("GET", url, true);
xmlhttp.send(null);
}
If you want this to work with Internet Explorer you’ll need to include this compatibility patch. |
2005 |
Simon Willison |
simonwillison |
2005-12-07T00:00:00+00:00 |
https://24ways.org/2005/dont-be-eval/ |
code |
| 314 |
Easy Ajax with Prototype |
There’s little more impressive on the web today than a appropriate touch of Ajax. Used well, Ajax brings a web interface much closer to the experience of a desktop app, and can turn a bear of an task into a pleasurable activity.
But it’s really hard, right? It involves all the nasty JavaScript that no one ever does often enough to get really good at, and the browser support is patchy, and urgh it’s just so much damn effort. Well, the good news is that – ta-da – it doesn’t have to be a headache. But man does it still look impressive. Here’s how to amaze your friends.
Introducing prototype.js
Prototype is a JavaScript framework by Sam Stephenson designed to help make developing dynamic web apps a whole lot easier. In basic terms, it’s a JavaScript file which you link into your page that then enables you to do cool stuff.
There’s loads of capability built in, a portion of which covers our beloved Ajax. The whole thing is freely distributable under an MIT-style license, so it’s good to go. What a nice man that Mr Stephenson is – friends, let us raise a hearty cup of mulled wine to his good name. Cheers! sluurrrrp.
First step is to download the latest Prototype and put it somewhere safe. I suggest underneath the Christmas tree.
Cutting to the chase
Before I go on and set up an example of how to use this, let’s just get to the crux. Here’s how Prototype enables you to make a simple Ajax call and dump the results back to the page:
var url = 'myscript.php';
var pars = 'foo=bar';
var target = 'output-div';
var myAjax = new Ajax.Updater(target, url, {method: 'get', parameters: pars});
This snippet of JavaScript does a GET to myscript.php, with the parameter foo=bar, and when a result is returned, it places it inside the element with the ID output-div on your page.
Knocking up a basic example
So to get this show on the road, there are three files we need to set up in our site alongside prototype.js. Obviously we need a basic HTML page with prototype.js linked in. This is the page the user interacts with. Secondly, we need our own JavaScript file for the glue between the interface and the stuff Prototype is doing. Lastly, we need the page (a PHP script in my case) that the Ajax is going to make its call too.
So, to that basic HTML page for the user to interact with. Here’s one I found whilst out carol singing:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8"/>
<title>Easy Ajax</title>
<script type="text/javascript" src="prototype.js"></script>
<script type="text/javascript" src="ajax.js"></script>
</head>
<body>
<form method="get" action="greeting.php" id="greeting-form">
<div>
<label for="greeting-name">Enter your name:</label>
<input id="greeting-name" type="text" />
<input id="greeting-submit" type="submit" value="Greet me!" />
</div>
<div id="greeting"></div>
</form>
</body>
</html>
As you can see, I’ve linked in prototype.js, and also a file called ajax.js, which is where we’ll be putting our glue. (Careful where you leave your glue, kids.)
Our basic example is just going to take a name and then echo it back in the form of a seasonal greeting. There’s a form with an input field for a name, and crucially a DIV (greeting) for the result of our call. You’ll also notice that the form has a submit button – this is so that it can function as a regular form when no JavaScript is available. It’s important not to get carried away and forget the basics of accessibility.
Meanwhile, back at the server
So we need a script at the server which is going to take input from the Ajax call and return some output. This is normally where you’d hook into a database and do whatever transaction you need to before returning a result. To keep this as simple as possible, all this example here will do is take the name the user has given and add it to a greeting message. Not exactly Web 2-point-HoHoHo, but there you have it.
Here’s a quick PHP script – greeting.php – that Santa brought me early.
<?php
$the_name = htmlspecialchars($_GET['greeting-name']);
echo "<p>Season's Greetings, $the_name!</p>";
?>
You’ll perhaps want to do something a little more complex within your own projects. Just sayin’.
Gluing it all together
Inside our ajax.js file, we need to hook this all together. We’re going to take advantage of some of the handy listener routines and such that Prototype also makes available. The first task is to attach a listener to set the scene once the window has loaded. He’s how we attach an onload event to the window object and get it to call a function named init():
Event.observe(window, 'load', init, false);
Now we create our init() function to do our evil bidding. Its first job of the day is to hide the submit button for those with JavaScript enabled. After that, it attaches a listener to watch for the user typing in the name field.
function init(){
$('greeting-submit').style.display = 'none';
Event.observe('greeting-name', 'keyup', greet, false);
}
As you can see, this is going to make a call to a function called greet() onkeyup in the greeting-name field. That function looks like this:
function greet(){
var url = 'greeting.php';
var pars = 'greeting-name='+escape($F('greeting-name'));
var target = 'greeting';
var myAjax = new Ajax.Updater(target, url, {method: 'get', parameters: pars});
}
The key points to note here are that any user input needs to be escaped before putting into the parameters so that it’s URL-ready. The target is the ID of the element on the page (a DIV in our case) which will be the recipient of the output from the Ajax call.
That’s it
No, seriously. That’s everything. Try the example. Amaze your friends with your 1337 Ajax sk1llz. |
2005 |
Drew McLellan |
drewmclellan |
2005-12-01T00:00:00+00:00 |
https://24ways.org/2005/easy-ajax-with-prototype/ |
code |
| 315 |
Edit-in-Place with Ajax |
Back on day one we looked at using the Prototype library to take all the hard work out of making a simple Ajax call. While that was fun and all, it didn’t go that far towards implementing something really practical. We dipped our toes in, but haven’t learned to swim yet.
So here is swimming lesson number one. Anyone who’s used Flickr to publish their photos will be familiar with the edit-in-place system used for quickly amending titles and descriptions on photographs. Hovering over an item turns its background yellow to indicate it is editable. A simple click loads the text into an edit box, right there on the page.
Prototype includes all sorts of useful methods to help reproduce something like this for our own projects. As well as the simple Ajax GETs we learned how to do last time, we can also do POSTs (which we’ll need here) and a whole bunch of manipulations to the user interface – all through simple library calls. Here’s what we’re building, so let’s do it.
Getting Started
There are two major components to this process; the user interface manipulation and the Ajax call itself. Our set-up is much the same as last time (you may wish to read the first article if you’ve not already done so). We have a basic HTML page which links in the prototype.js file and our own editinplace.js. Here’s what Santa dropped down my chimney:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8"/>
<title>Edit-in-Place with Ajax</title>
<link href="editinplace.css" rel="Stylesheet" type="text/css" />
<script src="prototype.js" type="text/javascript"></script>
<script src="editinplace.js" type="text/javascript"></script>
</head>
<body>
<h1>Edit-in-place</h1>
<p id="desc">Dashing through the snow on a one horse open sleigh.</p>
</body>
</html>
So that’s our page. The editable item is going to be the <p> called desc. The process goes something like this:
Highlight the area onMouseOver
Clear the highlight onMouseOut
If the user clicks, hide the area and replace with a <textarea> and buttons
Remove all of the above if the user cancels the operation
When the Save button is clicked, make an Ajax POST and show that something’s happening
When the Ajax call comes back, update the page with the new content
Events and Highlighting
The first step is to offer feedback to the user that the item is editable. This is done by shading the background colour when the user mouses over. Of course, the CSS :hover pseudo class is a straightforward way to do this, but for three reasons, I’m using JavaScript to switch class names.
:hover isn’t supported on many elements in Internet Explorer for Windows
I want to keep control over when the highlight switches off after an update, regardless of mouse position
If JavaScript isn’t available we don’t want to end up with the CSS suggesting it might be
With this in mind, here’s how editinplace.js starts:
Event.observe(window, 'load', init, false);
function init(){
makeEditable('desc');
}
function makeEditable(id){
Event.observe(id, 'click', function(){edit($(id))}, false);
Event.observe(id, 'mouseover', function(){showAsEditable($(id))}, false);
Event.observe(id, 'mouseout', function(){showAsEditable($(id), true)}, false);
}
function showAsEditable(obj, clear){
if (!clear){
Element.addClassName(obj, 'editable');
}else{
Element.removeClassName(obj, 'editable');
}
}
The first line attaches an onLoad event to the window, so that the function init() gets called once the page has loaded. In turn, init() sets up all the items on the page that we want to make editable. In this example I’ve just got one, but you can add as many as you like.
The function madeEditable() attaches the mouseover, mouseout and click events to the item we’re making editable. All showAsEditable does is add and remove the class name editable from the object. This uses the particularly cunning methods Element.addClassName() and Element.removeClassName() which enable you to cleanly add and remove effects without affecting any styling the object may otherwise have.
Oh, remember to add a rule for .editable to your style sheet:
.editable{
color: #000;
background-color: #ffffd3;
}
The Switch
As you can see above, when the user clicks on an editable item, a call is made to the function edit(). This is where we switch out the static item for a nice editable textarea. Here’s how that function looks.
function edit(obj){
Element.hide(obj);
var textarea ='<div id="' + obj.id + '_editor">
<textarea id="' + obj.id + '_edit" name="' + obj.id + '" rows="4" cols="60">'
+ obj.innerHTML + '</textarea>';
var button = '<input id="' + obj.id + '_save" type="button" value="SAVE" /> OR
<input id="' + obj.id + '_cancel" type="button" value="CANCEL" /></div>';
new Insertion.After(obj, textarea+button);
Event.observe(obj.id+'_save', 'click', function(){saveChanges(obj)}, false);
Event.observe(obj.id+'_cancel', 'click', function(){cleanUp(obj)}, false);
}
The first thing to do is to hide the object. Prototype comes to the rescue with Element.hide() (and of course, Element.show() too). Following that, we build up the textarea and buttons as a string, and then use Insertion.After() to place our new editor underneath the (now hidden) editable object.
The last thing to do before we leave the user to edit is it attach listeners to the Save and Cancel buttons to call either the saveChanges() function, or to cleanUp() after a cancel.
In the event of a cancel, we can clean up behind ourselves like so:
function cleanUp(obj, keepEditable){
Element.remove(obj.id+'_editor');
Element.show(obj);
if (!keepEditable) showAsEditable(obj, true);
}
Saving the Changes
This is where all the Ajax fun occurs. Whilst the previous article introduced Ajax.Updater() for simple Ajax calls, in this case we need a little bit more control over what happens once the response is received. For this purpose, Ajax.Request() is perfect. We can use the onSuccess and onFailure parameters to register functions to handle the response.
function saveChanges(obj){
var new_content = escape($F(obj.id+'_edit'));
obj.innerHTML = "Saving...";
cleanUp(obj, true);
var success = function(t){editComplete(t, obj);}
var failure = function(t){editFailed(t, obj);}
var url = 'edit.php';
var pars = 'id=' + obj.id + '&content=' + new_content;
var myAjax = new Ajax.Request(url, {method:'post',
postBody:pars, onSuccess:success, onFailure:failure});
}
function editComplete(t, obj){
obj.innerHTML = t.responseText;
showAsEditable(obj, true);
}
function editFailed(t, obj){
obj.innerHTML = 'Sorry, the update failed.';
cleanUp(obj);
}
As you can see, we first grab in the contents of the textarea into the variable new_content. We then remove the editor, set the content of the original object to “Saving…” to show that an update is occurring, and make the Ajax POST.
If the Ajax fails, editFailed() sets the contents of the object to “Sorry, the update failed.” Admittedly, that’s not a very helpful way to handle the error but I have to limit the scope of this article somewhere. It might be a good idea to stow away the original contents of the object (obj.preUpdate = obj.innerHTML) for later retrieval before setting the content to “Saving…”. No one likes a failure – especially a messy one.
If the Ajax call is successful, the server-side script returns the edited content, which we then place back inside the object from editComplete, and tidy up.
Meanwhile, back at the server
The missing piece of the puzzle is the server-side script for committing the changes to your database. Obviously, any solution I provide here is not going to fit your particular application. For the purposes of getting a functional demo going, here’s what I have in PHP.
<?php
$id = $_POST['id'];
$content = $_POST['content'];
echo htmlspecialchars($content);
?>
Not exactly rocket science is it? I’m just catching the content item from the POST and echoing it back. For your application to be useful, however, you’ll need to know exactly which record you should be updating. I’m passing in the ID of my <div>, which is not a fat lot of use. You can modify saveChanges() to post back whatever information your app needs to know in order to process the update.
You should also check the user’s credentials to make sure they have permission to edit whatever it is they’re editing. Basically the same rules apply as with any script in your application.
Limitations
There are a few bits and bobs that in an ideal world I would tidy up. The first is the error handling, as I’ve already mentioned. The second is that from an idealistic standpoint, I’d rather not be using innerHTML. However, the reality is that it’s presently the most efficient way of making large changes to the document. If you’re serving as XML, remember that you’ll need to replace these with proper DOM nodes.
It’s also important to note that it’s quite difficult to make something like this universally accessible. Whenever you start updating large chunks of a document based on user interaction, a lot of non-traditional devices don’t cope well. The benefit of this technique, though, is that if JavaScript is unavailable none of the functionality gets implemented at all – it fails silently. It is for this reason that this shouldn’t be used as a complete replacement for a traditional, universally accessible edit form. It’s a great time-saver for those with the ability to use it, but it’s no replacement.
See it in action
I’ve put together an example page using the inert PHP script above. That is to say, your edits aren’t committed to a database, so the example is reset when the page is reloaded. |
2005 |
Drew McLellan |
drewmclellan |
2005-12-23T00:00:00+00:00 |
https://24ways.org/2005/edit-in-place-with-ajax/ |
code |
| 238 |
Everything You Wanted To Know About Gradients (And a Few Things You Didn’t) |
Hello. I am here to discuss CSS3 gradients. Because, let’s face it, what the web really needed was more gradients.
Still, despite their widespread use (or is it overuse?), the smartly applied gradient can be a valuable contributor to a designer’s vocabulary. There’s always been a tension between the inherently two-dimensional nature of our medium, and our desire for more intensity, more depth in our designs. And a gradient can evoke so much: the splay of light across your desk, the slow decrease in volume toward the end of your favorite song, the sunset after a long day. When properly applied, graded colors bring a much needed softness to our work.
Of course, that whole ‘proper application’ thing is the tricky bit.
But given their place in our toolkit and their prominence online, it really is heartening to see we can create gradients directly with CSS. They’re part of the draft images module, and implemented in two of the major rendering engines.
Still, I’ve always found CSS gradients to be one of the more confusing aspects of CSS3. So if you’ll indulge me, let’s take a quick look at how to create CSS gradients—hopefully we can make them seem a bit more accessible, and bring a bit more art into the browser.
Gradient theory 101 (I hope that’s not really a thing)
Right. So before we dive into the code, let’s cover a few basics. Every gradient, no matter how complex, shares a few common characteristics. Here’s a straightforward one:
I spent seconds hours designing this gradient. I hope you like it.
At either end of our image, we have a final color value, or color stop: on the left, our stop is white; on the right, black. And more color-rich gradients are no different:
(Don’t ever really do this. Please. I beg you.)
It’s visually more intricate, sure. But at the heart of it, we have just seven color stops (red, orange, yellow, and so on), making for a fantastic gradient all the way.
Now, color stops alone do not a gradient make. Between each is a transition point, the fail-over point between the two stops. Now, the transition point doesn’t need to fall exactly between stops: it can be brought closer to one stop or the other, influencing the overall shape of the gradient.
A tale of two syntaxes
Armed with our new vocabulary, let’s look at a CSS gradient in the wild. Behold, the simple input button:
There’s a simple linear gradient applied vertically across the button, moving from a bright sunflowerish hue (#FAA51A, for you hex nuts in the audience) to a much richer orange (#F47A20). And here’s the CSS that makes it happen:
input[type=submit] {
background-color: #F47A20;
background-image: -moz-linear-gradient(
#FAA51A,
#F47A20
);
background-image: -webkit-gradient(linear, 0 0, 0 100%,
color-stop(0, #FAA51A),
color-stop(1, #F47A20)
);
}
I’ve borrowed David DeSandro’s most excellent formatting suggestions for gradients to make this snippet a bit more legible but, still, the code above might have turned your stomach a bit. And that’s perfectly understandable—heck, it sort of turned mine. But let’s step through the CSS slowly, and see if we can’t make it a little less terrifying.
Verbose WebKit is verbose
Here’s the syntax for our little gradient on WebKit:
background-image: -webkit-gradient(linear, 0 0, 0 100%,
color-stop(0, #FAA51A),
color-stop(1, #F47A20)
);
Woof. Quite a mouthful, no? Well, here’s what we’re looking at:
WebKit has a single -webkit-gradient property, which can be used to create either linear or radial gradients.
The next two values are the starting and ending positions for our gradient (0 0 and 0 100%, respectively). Linear gradients are simply drawn along the path between those two points, which allows us to change the direction of our gradient simply by altering its start and end points.
Afterward, we specify our color stops with the oh-so-aptly named color-stop parameter, which takes the stop’s position on the gradient (0 being the beginning, and 100% or 1 being the end) and the color itself.
For a simple two-color gradient like this, -webkit-gradient has a bit of shorthand notation to offer us:
background-image: -webkit-gradient(linear, 0 0, 0 100%,
from(#FAA51A),
to(#FAA51A)
);
from(#FAA51A) is equivalent to writing color-stop(0, #FAA51A), and to(#FAA51A) is the same as color-stop(1, #FAA51A) or color-stop(100%, #FAA51A)—in both cases, we’re simply declaring the first and last color stops in our gradient.
Terse Gecko is terse
WebKit proposed its syntax back in 2008, heavily inspired by the way gradients are drawn in the canvas specification. However, a different, leaner syntax came to the fore, eventually appearing in a draft module specification in CSS3.
Naturally, because nothing on the web was meant to be easy, this is the one that Mozilla has implemented.
Here’s how we get gradient-y in Gecko:
background-image: -moz-linear-gradient(
#FAA51A,
#F47A20
);
Wait, what? Done already? That’s right. By default, -moz-linear-gradient assumes you’re trying to create a vertical gradient, starting from the top of your element and moving to the bottom. And, if that’s the case, then you simply need to specify your color stops, delimited with a few commas.
I know: that was almost… painless. But the W3C/Mozilla syntax also affords us a fair amount of flexibility and control, by introducing features as we need them.
We can specify an origin point for our gradient:
background-image: -moz-linear-gradient(50% 100%,
#FAA51A,
#F47A20
);
As well as an angle, to give it a direction:
background-image: -moz-linear-gradient(50% 100%, 45deg,
#FAA51A,
#F47A20
);
And we can specify multiple stops, simply by adding to our comma-delimited list:
background-image: -moz-linear-gradient(50% 100%, 45deg,
#FAA51A,
#FCC,
#F47A20
);
By adding a percentage after a given color value, we can determine its position along the gradient path:
background-image: -moz-linear-gradient(50% 100%, 45deg,
#FAA51A,
#FCC 20%,
#F47A20
);
So that’s some of the flexibility implicit in the W3C/Mozilla-style syntax.
Now, I should note that both syntaxes have their respective fans. I will say that the W3C/Mozilla-style syntax makes much more sense to me, and lines up with how I think about creating gradients. But I can totally understand why some might prefer WebKit’s more verbose approach to the, well, looseness behind the -moz syntax. À chacun son gradient syntax.
Still, as the language gets refined by the W3C, I really hope some consensus is reached by the browser vendors. And with Opera signaling that it will support the W3C syntax, I suppose it falls on WebKit to do the same.
Reusing color stops for fun and profit
But CSS gradients aren’t all simple colors and shapes and whatnot: by getting inventive with individual color stops, you can create some really complex, compelling effects.
Tim Van Damme, whose brain, I believe, should be posthumously donated to science, has a particularly clever application of gradients on The Box, a site dedicated to his occasional podcast series. Now, there are a fair number of gradients applied throughout the UI, but it’s the feature image that really catches the eye.
You see, there’s nothing that says you can’t reuse color stops. And Tim’s exploited that perfectly.
He’s created a linear gradient, angled at forty-five degrees from the top left corner of the photo, starting with a fully transparent white (rgba(255, 255, 255, 0)). At the halfway mark, he’s established another color stop at an only slightly more opaque white (rgba(255, 255, 255, 0.1)), making for that incredibly gradual brightening toward the middle of the photo.
But then he has set another color stop immediately on top of it, bringing it back down to rgba(255, 255, 255, 0) again. This creates that fantastically hard edge that diagonally bisects the photo, giving the image that subtle gloss.
And his final color stop ends at the same fully transparent white, completing the effect. Hot? I do believe so.
Rocking the radials
We’ve been looking at linear gradients pretty exclusively. But I’d be remiss if I didn’t at least mention radial gradients as a viable option, including a modest one as a link accent on a navigation bar:
And here’s the relevant CSS:
background: -moz-radial-gradient(50% 100%, farthest-side,
rgb(204, 255, 255) 1%,
rgb(85, 85, 85) 15%,
rgba(85, 85, 85, 0)
);
background: -webkit-gradient(radial, 50% 100%, 0, 50% 100%, 15,
from(rgb(204, 255, 255)),
to(rgba(85, 85, 85, 0))
);
Now, the syntax builds on what we’ve already learned about linear gradients, so much of it might be familiar to you, picking out color stops and transition points, as well as the two syntaxes’ reliance on either a separate property (-moz-radial-gradient) or parameter (-webkit-gradient(radial, …)) to shift into circular mode.
Mozilla introduces another stand-alone property (-moz-radial-gradient), and accepts a starting point (50% 100%) from which the circle radiates. There’s also a size constant defined (farthest-side), which determines the reach and shape of our gradient.
WebKit is again the more verbose of the two syntaxes, requiring both starting and ending points (50% 100% in both cases). Each also accepts a radius in pixels, allowing you to control the skew and breadth of the circle.
Again, this is a fairly modest little radial gradient. Time and article length (and, let’s be honest, your author’s completely inadequate grasp of geometry) prevent me from covering radial gradients in much more detail, because they are incredibly powerful. For those interested in learning more, I can’t recommend the references at Mozilla and Apple strongly enough.
Leave no browser behind
But no matter the kind of gradients you’re working with, there is a large swathe of browsers that simply don’t support gradients. Thankfully, it’s fairly easy to declare a sensible fallback—it just depends on the kind of fallback you’d like. Essentially, gradient-blind browsers will disregard any properties containing references to either -moz-linear-gradient, -moz-radial-gradient, or -webkit-gradient, so you simply need to keep your fallback isolated from those properties.
For example: if you’d like to fall back to a flat color, simply declare a separate background-color:
.nav {
background-color: #000;
background-image: -moz-linear-gradient(rgba(0, 0, 0, 0), rgba(255, 255, 255, 0.45));
background-image: -webkit-gradient(linear, 0 0, 0 100%, from(rgba(0, 0, 0, 0)), to(rgba(255, 255, 255, 0.45)));
}
Or perhaps just create three separate background properties.
.nav {
background: #000;
background: #000 -moz-linear-gradient(rgba(0, 0, 0, 0), rgba(255, 255, 255, 0.45));
background: #000 -webkit-gradient(linear, 0 0, 0 100%, from(rgba(0, 0, 0, 0)), to(rgba(255, 255, 255, 0.45)));
}
We can even build on this to fall back to a non-gradient image:
.nav {
background: #000 <strong>url("faux-gradient-lol.png") repeat-x</strong>;
background: #000 -moz-linear-gradient(rgba(0, 0, 0, 0), rgba(255, 255, 255, 0.45));
background: #000 -webkit-gradient(linear, 0 0, 0 100%, from(rgba(0, 0, 0, 0)), to(rgba(255, 255, 255, 0.45)));
}
No matter the approach you feel most appropriate to your design, it’s really just a matter of keeping your fallback design quarantined from its CSS3-ified siblings.
(If you’re feeling especially masochistic, there’s even a way to get simple linear gradients working in IE via Microsoft’s proprietary filters. Of course, those come with considerable performance penalties that even Microsoft is quick to point out, so I’d recommend avoiding those.
And don’t tell Andy Clarke I told you, or he’ll probably unload his Derringer at me. Or something.)
Go forth and, um, gradientify!
It’s entirely possible your head’s spinning. Heck, mine is, but that might be the effects of the ’nog. But maybe you’re wondering why you should care about CSS gradients. After all, images are here right now, and work just fine.
Well, there are some quick benefits that spring to mind: fewer HTTP requests are needed; CSS3 gradients are easily made scalable, making them ideal for variable widths and heights; and finally, they’re easily modifiable by tweaking a few CSS properties. Because, let’s face it, less time spent yelling at Photoshop is a very, very good thing.
Of course, CSS-generated gradients are not without their drawbacks. The syntax can be confusing, and it’s still under development at the W3C. As we’ve seen, browser support is still very much in flux. And it’s possible that gradients themselves have some real performance drawbacks—so test thoroughly, and gradient carefully.
But still, as syntaxes converge, and support improves, I think generated gradients can make a compelling tool in our collective belts. The tasteful design is, of course, entirely up to you.
So have fun, and get gradientin’. |
2010 |
Ethan Marcotte |
ethanmarcotte |
2010-12-22T00:00:00+00:00 |
https://24ways.org/2010/everything-you-wanted-to-know-about-gradients/ |
code |
| 249 |
Fast Autocomplete Search for Your Website |
Every website deserves a great search engine - but building a search engine can be a lot of work, and hosting it can quickly get expensive.
I’m going to build a search engine for 24 ways that’s fast enough to support autocomplete (a.k.a. typeahead) search queries and can be hosted for free. I’ll be using wget, Python, SQLite, Jupyter, sqlite-utils and my open source Datasette tool to build the API backend, and a few dozen lines of modern vanilla JavaScript to build the interface.
Try it out here, then read on to see how I built it.
First step: crawling the data
The first step in building a search engine is to grab a copy of the data that you plan to make searchable.
There are plenty of potential ways to do this: you might be able to pull it directly from a database, or extract it using an API. If you don’t have access to the raw data, you can imitate Google and write a crawler to extract the data that you need.
I’m going to do exactly that against 24 ways: I’ll build a simple crawler using wget, a command-line tool that features a powerful “recursive” mode that’s ideal for scraping websites.
We’ll start at the https://24ways.org/archives/ page, which links to an archived index for every year that 24 ways has been running.
Then we’ll tell wget to recursively crawl the website, using the --recursive flag.
We don’t want to fetch every single page on the site - we’re only interested in the actual articles. Luckily, 24 ways has nicely designed URLs, so we can tell wget that we only care about pages that start with one of the years it has been running, using the -I argument like this: -I /2005,/2006,/2007,/2008,/2009,/2010,/2011,/2012,/2013,/2014,/2015,/2016,/2017
We want to be polite, so let’s wait for 2 seconds between each request rather than hammering the site as fast as we can: --wait 2
The first time I ran this, I accidentally downloaded the comments pages as well. We don’t want those, so let’s exclude them from the crawl using -X "/*/*/comments".
Finally, it’s useful to be able to run the command multiple times without downloading pages that we have already fetched. We can use the --no-clobber option for this.
Tie all of those options together and we get this command:
wget --recursive --wait 2 --no-clobber
-I /2005,/2006,/2007,/2008,/2009,/2010,/2011,/2012,/2013,/2014,/2015,/2016,/2017
-X "/*/*/comments"
https://24ways.org/archives/
If you leave this running for a few minutes, you’ll end up with a folder structure something like this:
$ find 24ways.org
24ways.org
24ways.org/2013
24ways.org/2013/why-bother-with-accessibility
24ways.org/2013/why-bother-with-accessibility/index.html
24ways.org/2013/levelling-up
24ways.org/2013/levelling-up/index.html
24ways.org/2013/project-hubs
24ways.org/2013/project-hubs/index.html
24ways.org/2013/credits-and-recognition
24ways.org/2013/credits-and-recognition/index.html
...
As a quick sanity check, let’s count the number of HTML pages we have retrieved:
$ find 24ways.org | grep index.html | wc -l
328
There’s one last step! We got everything up to 2017, but we need to fetch the articles for 2018 (so far) as well. They aren’t linked in the /archives/ yet so we need to point our crawler at the site’s front page instead:
wget --recursive --wait 2 --no-clobber
-I /2018
-X "/*/*/comments"
https://24ways.org/
Thanks to --no-clobber, this is safe to run every day in December to pick up any new content.
We now have a folder on our computer containing an HTML file for every article that has ever been published on the site! Let’s use them to build ourselves a search index.
Building a search index using SQLite
There are many tools out there that can be used to build a search engine. You can use an open-source search server like Elasticsearch or Solr, a hosted option like Algolia or Amazon CloudSearch or you can tap into the built-in search features of relational databases like MySQL or PostgreSQL.
I’m going to use something that’s less commonly used for web applications but makes for a powerful and extremely inexpensive alternative: SQLite.
SQLite is the world’s most widely deployed database, even though many people have never even heard of it. That’s because it’s designed to be used as an embedded database: it’s commonly used by native mobile applications and even runs as part of the default set of apps on the Apple Watch!
SQLite has one major limitation: unlike databases like MySQL and PostgreSQL, it isn’t really designed to handle large numbers of concurrent writes. For this reason, most people avoid it for building web applications.
This doesn’t matter nearly so much if you are building a search engine for infrequently updated content - say one for a site that only publishes new content on 24 days every year.
It turns out SQLite has very powerful full-text search functionality built into the core database - the FTS5 extension.
I’ve been doing a lot of work with SQLite recently, and as part of that, I’ve been building a Python utility library to make building new SQLite databases as easy as possible, called sqlite-utils. It’s designed to be used within a Jupyter notebook - an enormously productive way of interacting with Python code that’s similar to the Observable notebooks Natalie described on 24 ways yesterday.
If you haven’t used Jupyter before, here’s the fastest way to get up and running with it - assuming you have Python 3 installed on your machine. We can use a Python virtual environment to ensure the software we are installing doesn’t clash with any other installed packages:
$ python3 -m venv ./jupyter-venv
$ ./jupyter-venv/bin/pip install jupyter
# ... lots of installer output
# Now lets install some extra packages we will need later
$ ./jupyter-venv/bin/pip install beautifulsoup4 sqlite-utils html5lib
# And start the notebook web application
$ ./jupyter-venv/bin/jupyter-notebook
# This will open your browser to Jupyter at http://localhost:8888/
You should now be in the Jupyter web application. Click New -> Python 3 to start a new notebook.
A neat thing about Jupyter notebooks is that if you publish them to GitHub (either in a regular repository or as a Gist), it will render them as HTML. This makes them a very powerful way to share annotated code. I’ve published the notebook I used to build the search index on my GitHub account.
Here’s the Python code I used to scrape the relevant data from the downloaded HTML files. Check out the notebook for a line-by-line explanation of what’s going on.
from pathlib import Path
from bs4 import BeautifulSoup as Soup
base = Path("/Users/simonw/Dropbox/Development/24ways-search")
articles = list(base.glob("*/*/*/*.html"))
# articles is now a list of paths that look like this:
# PosixPath('...24ways-search/24ways.org/2013/why-bother-with-accessibility/index.html')
docs = []
for path in articles:
year = str(path.relative_to(base)).split("/")[1]
url = 'https://' + str(path.relative_to(base).parent) + '/'
soup = Soup(path.open().read(), "html5lib")
author = soup.select_one(".c-continue")["title"].split(
"More information about"
)[1].strip()
author_slug = soup.select_one(".c-continue")["href"].split(
"/authors/"
)[1].split("/")[0]
published = soup.select_one(".c-meta time")["datetime"]
contents = soup.select_one(".e-content").text.strip()
title = soup.find("title").text.split(" ◆")[0]
try:
topic = soup.select_one(
'.c-meta a[href^="/topics/"]'
)["href"].split("/topics/")[1].split("/")[0]
except TypeError:
topic = None
docs.append({
"title": title,
"contents": contents,
"year": year,
"author": author,
"author_slug": author_slug,
"published": published,
"url": url,
"topic": topic,
})
After running this code, I have a list of Python dictionaries representing each of the documents that I want to add to the index. The list looks something like this:
[
{
"title": "Why Bother with Accessibility?",
"contents": "Web accessibility (known in other fields as inclus...",
"year": "2013",
"author": "Laura Kalbag",
"author_slug": "laurakalbag",
"published": "2013-12-10T00:00:00+00:00",
"url": "https://24ways.org/2013/why-bother-with-accessibility/",
"topic": "design"
},
{
"title": "Levelling Up",
"contents": "Hello, 24 ways. Iu2019m Ashley and I sell property ins...",
"year": "2013",
"author": "Ashley Baxter",
"author_slug": "ashleybaxter",
"published": "2013-12-06T00:00:00+00:00",
"url": "https://24ways.org/2013/levelling-up/",
"topic": "business"
},
...
My sqlite-utils library has the ability to take a list of objects like this and automatically create a SQLite database table with the right schema to store the data. Here’s how to do that using this list of dictionaries.
import sqlite_utils
db = sqlite_utils.Database("/tmp/24ways.db")
db["articles"].insert_all(docs)
That’s all there is to it! The library will create a new database and add a table to it called articles with the necessary columns, then insert all of the documents into that table.
(I put the database in /tmp/ for the moment - you can move it to a more sensible location later on.)
You can inspect the table using the sqlite3 command-line utility (which comes with OS X) like this:
$ sqlite3 /tmp/24ways.db
sqlite> .headers on
sqlite> .mode column
sqlite> select title, author, year from articles;
title author year
------------------------------ ------------ ----------
Why Bother with Accessibility? Laura Kalbag 2013
Levelling Up Ashley Baxte 2013
Project Hubs: A Home Base for Brad Frost 2013
Credits and Recognition Geri Coady 2013
Managing a Mind Christopher 2013
Run Ragged Mark Boulton 2013
Get Started With GitHub Pages Anna Debenha 2013
Coding Towards Accessibility Charlie Perr 2013
...
<Ctrl+D to quit>
There’s one last step to take in our notebook. We know we want to use SQLite’s full-text search feature, and sqlite-utils has a simple convenience method for enabling it for a specified set of columns in a table. We want to be able to search by the title, author and contents fields, so we call the enable_fts() method like this:
db["articles"].enable_fts(["title", "author", "contents"])
Introducing Datasette
Datasette is the open-source tool I’ve been building that makes it easy to both explore SQLite databases and publish them to the internet.
We’ve been exploring our new SQLite database using the sqlite3 command-line tool. Wouldn’t it be nice if we could use a more human-friendly interface for that?
If you don’t want to install Datasette right now, you can visit https://search-24ways.herokuapp.com/ to try it out against the 24 ways search index data. I’ll show you how to deploy Datasette to Heroku like this later in the article.
If you want to install Datasette locally, you can reuse the virtual environment we created to play with Jupyter:
./jupyter-venv/bin/pip install datasette
This will install Datasette in the ./jupyter-venv/bin/ folder. You can also install it system-wide using regular pip install datasette.
Now you can run Datasette against the 24ways.db file we created earlier like so:
./jupyter-venv/bin/datasette /tmp/24ways.db
This will start a local webserver running. Visit http://localhost:8001/ to start interacting with the Datasette web application.
If you want to try out Datasette without creating your own 24ways.db file you can download the one I created directly from https://search-24ways.herokuapp.com/24ways-ae60295.db
Publishing the database to the internet
One of the goals of the Datasette project is to make deploying data-backed APIs to the internet as easy as possible. Datasette has a built-in command for this, datasette publish. If you have an account with Heroku or Zeit Now, you can deploy a database to the internet with a single command. Here’s how I deployed https://search-24ways.herokuapp.com/ (running on Heroku’s free tier) using datasette publish:
$ ./jupyter-venv/bin/datasette publish heroku /tmp/24ways.db --name search-24ways
-----> Python app detected
-----> Installing requirements with pip
-----> Running post-compile hook
-----> Discovering process types
Procfile declares types -> web
-----> Compressing...
Done: 47.1M
-----> Launching...
Released v8
https://search-24ways.herokuapp.com/ deployed to Heroku
If you try this out, you’ll need to pick a different --name, since I’ve already taken search-24ways.
You can run this command as many times as you like to deploy updated versions of the underlying database.
Searching and faceting
Datasette can detect tables with SQLite full-text search configured, and will add a search box directly to the page. Take a look at http://search-24ways.herokuapp.com/24ways-b607e21/articles to see this in action.
SQLite search supports wildcards, so if you want autocomplete-style search where you don’t need to enter full words to start getting results you can add a * to the end of your search term. Here’s a search for access* which returns articles on accessibility:
http://search-24ways.herokuapp.com/24ways-ae60295/articles?_search=acces%2A
A neat feature of Datasette is the ability to calculate facets against your data. Here’s a page showing search results for svg with facet counts calculated against both the year and the topic columns:
http://search-24ways.herokuapp.com/24ways-ae60295/articles?_search=svg&_facet=year&_facet=topic
Every page visible via Datasette has a corresponding JSON API, which can be accessed using the JSON link on the page - or by adding a .json extension to the URL:
http://search-24ways.herokuapp.com/24ways-ae60295/articles.json?_search=acces%2A
Better search using custom SQL
The search results we get back from ../articles?_search=svg are OK, but the order they are returned in is not ideal - they’re actually being returned in the order they were inserted into the database! You can see why this is happening by clicking the View and edit SQL link on that search results page.
This exposes the underlying SQL query, which looks like this:
select rowid, * from articles where rowid in (
select rowid from articles_fts where articles_fts match :search
) order by rowid limit 101
We can do better than this by constructing a custom SQL query. Here’s the query we will use instead:
select
snippet(articles_fts, -1, 'b4de2a49c8', '8c94a2ed4b', '...', 100) as snippet,
articles_fts.rank, articles.title, articles.url, articles.author, articles.year
from articles
join articles_fts on articles.rowid = articles_fts.rowid
where articles_fts match :search || "*"
order by rank limit 10;
You can try this query out directly - since Datasette opens the underling SQLite database in read-only mode and enforces a one second time limit on queries, it’s safe to allow users to provide arbitrary SQL select queries for Datasette to execute.
There’s a lot going on here! Let’s break the SQL down line-by-line:
select
snippet(articles_fts, -1, 'b4de2a49c8', '8c94a2ed4b', '...', 100) as snippet,
We’re using snippet(), a built-in SQLite function, to generate a snippet highlighting the words that matched the query. We use two unique strings that I made up to mark the beginning and end of each match - you’ll see why in the JavaScript later on.
articles_fts.rank, articles.title, articles.url, articles.author, articles.year
These are the other fields we need back - most of them are from the articles table but we retrieve the rank (representing the strength of the search match) from the magical articles_fts table.
from articles
join articles_fts on articles.rowid = articles_fts.rowid
articles is the table containing our data. articles_fts is a magic SQLite virtual table which implements full-text search - we need to join against it to be able to query it.
where articles_fts match :search || "*"
order by rank limit 10;
:search || "*" takes the ?search= argument from the page querystring and adds a * to the end of it, giving us the wildcard search that we want for autocomplete. We then match that against the articles_fts table using the match operator. Finally, we order by rank so that the best matching results are returned at the top - and limit to the first 10 results.
How do we turn this into an API? As before, the secret is to add the .json extension. Datasette actually supports multiple shapes of JSON - we’re going to use ?_shape=array to get back a plain array of objects:
JSON API call to search for articles matching SVG
The HTML version of that page shows the time taken to execute the SQL in the footer. Hitting refresh a few times, I get response times between 2 and 5ms - easily fast enough to power a responsive autocomplete feature.
A simple JavaScript autocomplete search interface
I considered building this using React or Svelte or another of the myriad of JavaScript framework options available today, but then I remembered that vanilla JavaScript in 2018 is a very productive environment all on its own.
We need a few small utility functions: first, a classic debounce function adapted from this one by David Walsh:
function debounce(func, wait, immediate) {
let timeout;
return function() {
let context = this, args = arguments;
let later = () => {
timeout = null;
if (!immediate) func.apply(context, args);
};
let callNow = immediate && !timeout;
clearTimeout(timeout);
timeout = setTimeout(later, wait);
if (callNow) func.apply(context, args);
};
};
We’ll use this to only send fetch() requests a maximum of once every 100ms while the user is typing.
Since we’re rendering data that might include HTML tags (24 ways is a site about web development after all), we need an HTML escaping function. I’m amazed that browsers still don’t bundle a default one of these:
const htmlEscape = (s) => s.replace(
/>/g, '>'
).replace(
/</g, '<'
).replace(
/&/g, '&'
).replace(
/"/g, '"'
).replace(
/'/g, '''
);
We need some HTML for the search form, and a div in which to render the results:
<h1>Autocomplete search</h1>
<form>
<p><input id="searchbox" type="search" placeholder="Search 24ways" style="width: 60%"></p>
</form>
<div id="results"></div>
And now the autocomplete implementation itself, as a glorious, messy stream-of-consciousness of JavaScript:
// Embed the SQL query in a multi-line backtick string:
const sql = `select
snippet(articles_fts, -1, 'b4de2a49c8', '8c94a2ed4b', '...', 100) as snippet,
articles_fts.rank, articles.title, articles.url, articles.author, articles.year
from articles
join articles_fts on articles.rowid = articles_fts.rowid
where articles_fts match :search || "*"
order by rank limit 10`;
// Grab a reference to the <input type="search">
const searchbox = document.getElementById("searchbox");
// Used to avoid race-conditions:
let requestInFlight = null;
searchbox.onkeyup = debounce(() => {
const q = searchbox.value;
// Construct the API URL, using encodeURIComponent() for the parameters
const url = (
"https://search-24ways.herokuapp.com/24ways-866073b.json?sql=" +
encodeURIComponent(sql) +
`&search=${encodeURIComponent(q)}&_shape=array`
);
// Unique object used just for race-condition comparison
let currentRequest = {};
requestInFlight = currentRequest;
fetch(url).then(r => r.json()).then(d => {
if (requestInFlight !== currentRequest) {
// Avoid race conditions where a slow request returns
// after a faster one.
return;
}
let results = d.map(r => `
<div class="result">
<h3><a href="${r.url}">${htmlEscape(r.title)}</a></h3>
<p><small>${htmlEscape(r.author)} - ${r.year}</small></p>
<p>${highlight(r.snippet)}</p>
</div>
`).join("");
document.getElementById("results").innerHTML = results;
});
}, 100); // debounce every 100ms
There’s just one more utility function, used to help construct the HTML results:
const highlight = (s) => htmlEscape(s).replace(
/b4de2a49c8/g, '<b>'
).replace(
/8c94a2ed4b/g, '</b>'
);
This is what those unique strings passed to the snippet() function were for.
Avoiding race conditions in autocomplete
One trick in this code that you may not have seen before is the way race-conditions are handled. Any time you build an autocomplete feature, you have to consider the following case:
User types acces
Browser sends request A - querying documents matching acces*
User continues to type accessibility
Browser sends request B - querying documents matching accessibility*
Request B returns. It was fast, because there are fewer documents matching the full term
The results interface updates with the documents from request B, matching accessibility*
Request A returns results (this was the slower of the two requests)
The results interface updates with the documents from request A - results matching access*
This is a terrible user experience: the user saw their desired results for a brief second, and then had them snatched away and replaced with those results from earlier on.
Thankfully there’s an easy way to avoid this. I set up a variable in the outer scope called requestInFlight, initially set to null.
Any time I start a new fetch() request, I create a new currentRequest = {} object and assign it to the outer requestInFlight as well.
When the fetch() completes, I use requestInFlight !== currentRequest to sanity check that the currentRequest object is strictly identical to the one that was in flight. If a new request has been triggered since we started the current request we can detect that and avoid updating the results.
It’s not a lot of code, really
And that’s the whole thing! The code is pretty ugly, but when the entire implementation clocks in at fewer than 70 lines of JavaScript, I honestly don’t think it matters. You’re welcome to refactor it as much you like.
How good is this search implementation? I’ve been building search engines for a long time using a wide variety of technologies and I’m happy to report that using SQLite in this way is genuinely a really solid option. It scales happily up to hundreds of MBs (or even GBs) of data, and the fact that it’s based on SQL makes it easy and flexible to work with.
A surprisingly large number of desktop and mobile applications you use every day implement their search feature on top of SQLite.
More importantly though, I hope that this demonstrates that using Datasette for an API means you can build relatively sophisticated API-backed applications with very little backend programming effort. If you’re working with a small-to-medium amount of data that changes infrequently, you may not need a more expensive database. Datasette-powered applications easily fit within the free tier of both Heroku and Zeit Now.
For more of my writing on Datasette, check out the datasette tag on my blog. And if you do build something fun with it, please let me know on Twitter. |
2018 |
Simon Willison |
simonwillison |
2018-12-19T00:00:00+00:00 |
https://24ways.org/2018/fast-autocomplete-search-for-your-website/ |
code |
| 209 |
Feeding the Audio Graph |
In 2004, I was given an iPod.
I count this as one of the most intuitive pieces of technology I’ve ever owned. It wasn’t because of the the snazzy (colour!) menus or circular touchpad. I loved how smoothly it fitted into my life. I could plug in my headphones and listen to music while I was walking around town. Then when I got home, I could plug it into an amplifier and carry on listening there.
There was no faff. It didn’t matter if I could find my favourite mix tape, or if my WiFi was flakey - it was all just there.
Nowadays, when I’m trying to pair my phone with some Bluetooth speakers, or can’t find my USB-to-headphone jack, or even access any music because I don’t have cellular reception; I really miss this simplicity.
The Web Audio API
I think the Web Audio API feels kind of like my iPod did.
It’s different from most browser APIs - rather than throwing around data, or updating DOM elements - you plug together a graph of audio nodes, which the browser uses to generate, process, and play sounds.
The thing I like about it is that you can totally plug it into whatever you want, and it’ll mostly just work.
So, let’s get started. First of all we want an audio source.
<audio src="night-owl.mp3" controls />
(Song - Night Owl by Broke For Free)
This totally works. However, it’s not using the Web Audio API, so we can’t access or modify the sound it makes.
To hook this up to our audio graph, we can use an AudioSourceNode. This captures the sound from the element, and lets us connect to other nodes in a graph.
const audioCtx = new AudioContext()
const audio = document.querySelector('audio')
const input = audioCtx.createAudioSourceNode(audio)
input.connect(audioCtx.destination)
Great. We’ve made something that looks and sounds exactly the same as it did before. Go us.
Gain
Let’s plug in a GainNode - this allows you to alter the amplitude (volume) of an an audio stream.
We can hook this node up to an <input> element by setting the gain property of the node. (The syntax for this is kind of weird because it’s an AudioParam which has options to set values at precise intervals).
const node = audioCtx.createGain()
const input = document.querySelector('input')
input.oninput = () => node.gain.value = parseFloat(input.value)
input.connect(node)
node.connect(audioCtx.destination)
You can now see a range input, which can be dragged to update the state of our graph. This input could be any kind of element, so now you’ll be free to build the volume control of your dreams.
There’s a number of nodes that let you modify/filter an audio stream in more interesting ways. Head over to the MDN Web Audio page for a list of them.
Analysers
Something else we can add to our graph is an AnalyserNode. This doesn’t modify the audio at all, but allows us to inspect the sounds that are flowing through it. We can put this into our graph between our AudioSourceNode and the GainNode.
const analyser = audioCtx.createAnalyser()
input.connect(analyser)
analyser.connect(gain)
gain.connect(audioCtx.destination)
And now we have an analyser. We can access it from elsewhere to drive any kind of visuals. For instance, if we wanted to draw lines on a canvas we could totally do that:
const waveform = new Uint8Array(analyser.fftSize)
const frequencies = new Uint8Array(analyser.frequencyBinCount)
const ctx = canvas.getContext('2d')
const loop = () => {
requestAnimationFrame(loop)
analyser.getByteTimeDomainData(waveform)
analyser.getByteFrequencyData(frequencies)
ctx.beginPath()
waveform.forEach((f, i) => ctx.lineTo(i, f))
ctx.lineTo(0,255)
frequencies.forEach((f, i) => ctx.lineTo(i, 255-f))
ctx.stroke()
}
loop()
You can see that we have two arrays of data available (I added colours for clarity):
The waveform - the raw samples of the audio being played.
The frequencies - a fourier transform of the audio passing through the node.
What’s cool about this is that you’re not tied to any specific functionality of the Web Audio API. If it’s possible for you to update something with an array of numbers, then you can just apply it to the output of the analyser node.
For instance, if we wanted to, we could definitely animate a list of emoji in time with our music.
spans.forEach(
(s, i) => s.style.transform = `scale(${1 + (frequencies[i]/100)})`
)
🔈🎤🎤🎤🎺🎷📯🎶🔊🎸🎺🎤🎸🎼🎷🎺🎻🎸🎻🎺🎸🎶🥁🎶🎵🎵🎷📯🎸🎹🎤🎷🎻🎷🔈🔊📯🎼🎤🎵🎼📯🥁🎻🎻🎤🔉🎵🎹🎸🎷🔉🔈🔉🎷🎶🔈🎸🎸🎻🎤🥁🎼📯🎸🎸🎼🎸🥁🎼🎶🎶🥁🎤🔊🎷🔊🔈🎺🔊🎻🎵🎻🎸🎵🎺🎤🎷🎸🎶🎼📯🔈🎺🎤🎵🎸🎸🔊🎶🎤🥁🎵🎹🎸🔈🎻🔉🥁🔉🎺🔊🎹🥁🎷📯🎷🎷🎤🎸🔉🎹🎷🎸🎺🎼🎤🎼🎶🎷🎤🎷📯📯🎻🎤🎷📯🎹🔈🎵🎹🎼🔊🔉🔉🔈🎶🎸🥁🎺🔈🎷🎵🔉🥁🎷🎹🎷🔊🎤🎤🔊🎤🎤🎹🎸🎹🔉🎷
Generating Audio
So far, we’ve been using the <audio> element as a source of sound.
There’s a few other sources of audio that we can use. We’ll look at the AudioBufferNode - which allows you to manually generate a sound sample, and then connect it to our graph.
First we have to create an AudioBuffer, which holds our raw data, then we pass that to an AudioBufferNode which we can then treat just like our AudioSource node. This can get a bit boring, so we’ll use a helper method that makes it simpler to generate sounds.
const generator = (audioCtx, target) => (seconds, fn) => {
const { sampleRate } = audioCtx
const buffer = audioCtx.createBuffer(
1, sampleRate * seconds, sampleRate
)
const data = buffer.getChannelData(0)
for (var i = 0; i < data.length; i++) {
data[i] = fn(i / sampleRate, seconds)
}
return () => {
const source = audioCtx.createBufferSource()
source.buffer = audioBuffer
source.connect(target || audioCtx.destination)
source.start()
}
}
const sound = generator(audioCtx, gain)
Our wrapper will let us provide a function that maps time (in seconds) to a sample (between 1 and -1). This generates a waveform, like we saw before with the analyser node.
For example, the following will generate 0.75 seconds of white noise at 20% volume.
const noise = sound(0.75, t => Math.random() * 0.2)
button.onclick = noise
Noise
Now we’ve got a noisy button! Handy.
Rather than having a static set of audio nodes, each time we click the button, we add a new node to our graph. Although this feels inefficient, it’s not actually too bad - the browser can do a good job of cleaning up old nodes once they’ve played.
An interesting property of defining sounds as functions is that we can combine multiple function to generate new sounds. So if we wanted to fade our noise in and out, we could write a higher order function that does that.
const ease = fn => (t, s) =>
fn(t) * Math.sin((t / s) * Math.PI)
const noise = sound(0.75, ease(t => Math.random() * 0.2))
ease(noise)
And we can do more than just white noise - if we use Math.sin, we can generate some nice pure tones.
// Math.sin with period of 0..1
const wave = v => Math.sin(Math.PI * 2 * v)
const hz = f => t => wave(t * f)
const _440hz = sound(0.75, ease(hz(440)))
const _880hz = sound(0.75, ease(hz(880)))
440Hz
880Hz
We can also make our functions more complex. Below we’re combining several frequencies to make a richer sounding tone.
const harmony = f => [4, 3, 2, 1].reduce(
(v, h, i) => (sin(f * h) * (i+1) ) + v
)
const a440 = sound(0.75, ease(harmony(440)))
440Hz
880Hz
Cool.
We’re still not using any audio-specific functionality, so we can repurpose anything that does an operation on data. For example, we can use d3.js - usually used for interactive data visualisations - to generate a triangular waveform.
const triangle = d3.scaleLinear()
.domain([0, .5, 1])
.range([-1, 1, -1])
const wave = t => triangle(t % 1)
const a440 = sound(0.75, ease(harmony(440)))
440Hz
880Hz
It’s pretty interesting to play around with different functions. I’ve plonked everything in jsbin if you want to have a play yourself.
A departure from best practice
We’ve been generating our audio from scratch, but most of what we’ve looked at can be implemented by a series of native Web Audio nodes. This would be way performant (because it’s not happening on the main thread), and more flexible in some ways (because you can set timings dynamically whilst the note is playing). But we’re going to stay with this approach because it’s fun, and sometimes the fun thing to do might not technically be the best thing to do.
Making a keyboard
Having a button that makes a sound is totally great, but how about lots of buttons that make lots of sounds? Yup, totally greater-er.
The first thing we need to know is the frequency of each note. I thought this would be awkward because pianos were invented more than 250 years before the Hz unit was defined, so surely there wouldn’t be a simple mapping between the two?
const freq = note => 27.5 * Math.pow(2, (note - 21) / 12)
This equation blows my mind; I’d never really figured how tightly music and maths fit together. When you see a chord or melody, you can directly map it back to a mathematical pattern.
Our keyboard is actually an SVG picture of a keyboard, so we can traverse the elements of it and map each element to a sound generated by one of the functions that we came up with before.
Array.from(svg.querySelector('rect'))
.sort((a, b) => + a.x - b.x)
.forEach((key, i) =>
key.addEventListener('touchstart',
sound(0.75, ease(harmony(freq(i + 48))))
)
)
rect {stroke: #ddd;}
rect:hover {opacity: 0.8; stroke: #000}
Et voilà. We have a keyboard.
What I like about this is that it’s completely pure - there’s no lookup tables or hardcoded attributes; we’ve just defined a mapping from SVG elements to the sound they should probably make.
Doing better in the future
As I mentioned before, this could be implemented more performantly with Web Audio nodes, or even better - use something like Tone.js to be performant for you.
Web Audio has been around for a while, though we’re getting new challenges with immersive WebXR experiences, where spatial audio becomes really important. There’s also always support and API improvements (if you like AudioBufferNode, you’re going to love AudioWorklet)
Conclusion
And that’s about it. Web Audio isn’t some black box, you can easily link it with whatever framework, or UI that you’ve built (whether you should is an entirely different question).
If anyone ever asks you “could you turn this SVG into a musical instrument?” you don’t have to stare blankly at them any more.
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2017 |
Ben Foxall |
benfoxall |
2017-12-17T00:00:00+00:00 |
https://24ways.org/2017/feeding-the-audio-graph/ |
code |
| 298 |
First Steps in VR |
The web is all around us. As web folk, it is our responsibility to consider the impact our work can have. Part of this includes thinking about the future; the web changes lives and if we are building the web then we are the ones making decisions that affect people in every corner of the world. I find myself often torn between wanting to make the right decisions, and just wanting to have fun. To fiddle and play. We all know how important it is to sometimes just try ideas, whether they will amount to much or not.
I think of these two mindsets as production and prototyping, though of course there are lots of overlap and phases in between. I mention this because virtual reality is currently seen as a toy for rich people, and in some ways at the moment it is. But with WebVR we are able to create interesting experiences with a relatively low entry point. I want us to have open minds, play around with things, and then see how we can use the tools we have at our disposal to make things that will help people.
Every year we see articles saying it will be the “year of virtual reality”, that was especially prevalent this year. 2016 has been a year of progress, VR isn’t quite mainstream but with efforts like Playstation VR and Google Cardboard, we are definitely seeing much more of it. This year also saw the consumer editions of the Oculus Rift and HTC Vive. So it does seem to be a good time for an overview of how to get involved with creating virtual reality on the web.
WebVR is an API for connecting to devices and retrieving continuous data such as the position and orientation. Unlike the Web Audio API and some other APIs, WebVR does not feel like a framework. You use it however you want, taking the data and using it as you wish. To make it easier, there are plenty of resources such as Three.js, A-Frame and ReactVR that help to make the heavy lifting a bit easier.
Getting Started with A-Frame
I like taking the opportunity to learn new things whenever I can. So while planning this article I thought that instead of trying to teach WebGL or even Three.js in a way that is approachable for all, I would create my first project using A-Frame and write about that. This is not a tutorial as such, I just want to show how to go about getting involved with VR. The beauty of A-Frame is that it is very similar to web components, you can just write HTML to build worlds that will automatically work on all the different types of devices. It uses WebGL and WebVR but in such a way that it quite drastically reduces the learning curve. That’s not to say you can’t build complex things, you have complete access to write JavaScript and shaders.
I’m lazy. Whenever I learn a new language or framework I have found that the best way, personally, for me to learn is to have a project and to copy the starting code from someone else. A project lets you have a good idea of what you want to produce and it means you can ignore a lot of the irrelevant documentation, focussing purely on what you need. That reduces the stress of figuring things out. Copying code also makes it easier, because you know your boilerplate code is working. There’s nothing worse than getting stuck before anything actually works the first time. So I tinker. I take code and I modify it, I play around. It’s fun.
For this project I wanted to keep things as simple as possible, so I can easily explain it without the classic “draw a circle then draw an owl”. I wrote a list of requirements, with some stretch goals that you can give a try yourself if you fancy:
Must work on Google Cardboard at a minimum, because of price
Therefore, it must not rely on having a controller
Auto-moving around a maze would be a good example
Move in direction you look
Stretch goal: Scoring, time until you hit a wall or get stuck in maze
Stretch goal: Levels, so the map doesn’t need to be random
Stretch goal: Snow!
I decided to base this project on an example, Platforms, by Don McCurdy who wrote the really useful aframe-extras. Platforms has random 3D blocks that you can jump onto, going up into the sky. So I took his code and reduced it so that the blocks are randomly spread on the ground.
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width">
<title>24 ways</title>
<script src="https://aframe.io/releases/0.3.2/aframe.js"></script>
<script src="//cdn.rawgit.com/donmccurdy/aframe-extras/v2.6.1/dist/aframe-extras.min.js"></script>
</head>
<body>
<a-scene>
<a-entity id="player"
camera
universal-controls
kinematic-body
position="0 1.8 0">
</a-entity>
<a-entity id="walls"></a-entity>
<a-grid id="ground" static-body></a-grid>
<a-sky id="sky" color="#AADDF0"></a-sky>
<!-- Lighting -->
<a-light type="ambient" color="#ccc"></a-light>
</a-scene>
<script>
document.querySelector('a-scene').addEventListener('render-target-loaded', function () {
var MAP_SIZE = 10,
PLATFORM_SIZE = 5,
NUM_PLATFORMS = 50;
var platformsEl = document.querySelector('#walls');
var v, box;
for (var i = 0; i < NUM_PLATFORMS; i++) {
// y: 0 is ground
v = {
x: (Math.floor(Math.random() * MAP_SIZE) - PLATFORM_SIZE) * PLATFORM_SIZE,
y: PLATFORM_SIZE / 2,
z: (Math.floor(Math.random() * MAP_SIZE) - PLATFORM_SIZE) * PLATFORM_SIZE
};
box = document.createElement('a-box');
platformsEl.appendChild(box);
box.setAttribute('color', '#39BB82');
box.setAttribute('width', PLATFORM_SIZE);
box.setAttribute('height', PLATFORM_SIZE);
box.setAttribute('depth', PLATFORM_SIZE);
box.setAttribute('position', v.x + ' ' + v.y + ' ' + v.z);
box.setAttribute('static-body', '');
}
console.info('Platforms loaded.');
});
</script>
</body>
</html>
As you can see, this is very readable. Especially if you ignore the JavaScript that is used to create the maze. A-Frame (with A-Frame Extras) gives you a lot of power with relatively little to learn. We start with an <a-scene> which is the container for everything that is going to show up on the screen. There are a few <a-entity> which can be compared to <div> as they are essentially non-semantic containers, able to be used for any purpose. The attributes are used to define functionality, for example the camera attribute sets the entity to function as a camera and kinematic-body makes it collide instead of go through objects. Attributes are also used to set position and sizes, often using JavaScript to dynamically define them.
Styling
Now we’ve got the HTML written, we need to style it. To do this we add A-Frame compatible attributes such as color and material. I recommend playing around, you can get some quite impressive effects fairly easily. Originally I wanted a light snowy maze but it ended up being dark and foggy, as I really liked the feeling it gave.
Note, you will probably need a server running for images to work. You can do this by running python -m "SimpleHTTPServer" in the folder where the code is, then go to localhost:8000 in browser.
Textures
Unless you are going for a cartoony style, you probably want to find some textures. I found some on textures.com, one image worked well for the walls and the other for the floor.
<a-assets>
<img id="texture-floor" src="floor.jpg">
<img id="texture-wall" src="wall.jpg">
</a-assets>
The <a-assets> is used to define (as well as preload and cache) all assets, including images, audio and video. As you can see, images in the Asset Management System just use normal img tags. The ids are important here as we can use them later for using the textures.
To apply a texture to an object, you create a material. For a simple material where it just shows the image, you set the src to the id selector of the image.
Replace:
<a-grid id="ground" static-body></a-grid>
With:
<a-grid id="ground" static-body material="src: #texture-floor"></a-grid>
This will automatically make the image repeat over the entire floor, in my case filling it with bricks. The walls are pretty much identical, with the slight exception that it is set in JavaScript as they are dynamically defined.
box.setAttribute('material', 'src: #texture-wall');
That’s it for the textures, for now at least. These will not look completely realistic, as the light will bump off the rectangular wall rather than texture itself. This can be improved by using maps, textures that are used to modify the shape and physical properties of the object.
Lighting
The next part of styling is lighting. By using fog and different types of lighting, we are able to add atmospheric details to the game to make it feel that bit more realistic and polished.
There are lots of types of light in A-Frame (most coming from Three.js). You can add a light either by using the <a-light> entity or by attaching a light attribute to any other entity. If there are no lights defined then A-Frame adds some by default so that the scene is always lit.
To start with I wanted to light up the scene with a general light, type="ambient", so that the whole game felt slightly dark. I chose to set the light to a reddish colour #92455E. After playing around with intensity I chose 0.4, it added enough light to get the feeling I wanted without it being overly red. I also added a blue skybox (<a-sky>), as it looked a bit odd with a white sky.
<a-light type="ambient" color="#92455E" intensity="0.4"></a-light>
<a-sky id="sky" color="#0000ff"></a-sky>
I felt that the maze looked good with a red tinge but it was a bit flat, everything was the same colour and it was a bit dark. So I added a light within the #player entity, this could have been as an attribute but I set it as a child a-light instead. By using type="point" with a high intensity and low distance, it showed close walls as being lighter. It also added a sort-of object to the player, it isn’t a walking human or anything but by moving light where the player is it feels a bit more physical.
<a-light color="#fff" distance="5" intensity="0.7" type="point"></a-light>
By this point it was starting to look decent, so I wanted to add the fog to really give some personality and depth to the maze. To do this I added the fog attribute to the <a-scene> with type=exponential so it looks thicker the further away it is and a mid intensity, so you feel a bit lost but can still see.
I was very happy with this result. It took a lot of playing around with colours and values, which is fun in itself. I highly recommend you take the code (or write your own) and play around with the numbers.
Movement
One of the reasons I decided to use aframe-extras is that it has a few different camera controls built in. As you saw earlier, I am using the universal-controls which gives WASD (keyboard) controls by default. I wanted to make it automatically move in the direction that you’re looking, but I wasn’t quite sure how without rewriting the controls. So I asked Don McCurdy for advice and he very nicely gave me a small snippet of code to get it working.
AFRAME.registerComponent('automove-controls', {
init: function () {
this.speed = 0.1;
this.isMoving = true;
this.velocityDelta = new THREE.Vector3();
},
isVelocityActive: function () {
return this.isMoving;
},
getVelocityDelta: function () {
this.velocityDelta.z = this.isMoving ? -speed : 0;
return this.velocityDelta.clone();
}
});
Replace:
universal-controls
With:
universal-controls="movementControls: automove, gamepad, keyboard"
This works by creating a component automove-controls that adds auto-move to the player without overriding movement completely. It doesn’t even touch direction, it just checks if isMoving is true then moves the player by the set speed. Components can be creating for adding all kinds of functionality with relative ease. It makes it very powerful for people of all difficulty levels.
Building a map
Currently the maze is created randomly, which is great but means there will often be walls that overlap or the player gets trapped with nowhere to go. So to solve this, I decided to use a map editor (Tiled) so that we can create the mazes ourselves. This is a great start towards one of the stretch goals, levels.
I made the maze in Tiled by finding a random tileset online (we don’t need to actually show the images), I used one tile for the wall and another for the player. Then I exported as a JavaScript file and modified it in my text editor to get rid of everything I didn’t need. I made it so 0 is the path, 1 is the wall and 2 is the player. I then added the script to the HTML, as a separate file so it’s easy to update in the future.
var map =
{
"data":[1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 1, 0, 1, 1, 0, 1, 1, 0, 1, 1, 1, 0, 1, 1, 0, 1, 0, 0, 0, 0, 0, 0, 1, 1, 0, 1, 0, 1, 0, 1, 0, 0, 1, 1, 0, 0, 0, 1, 0, 1, 1, 0, 1, 1, 0, 1, 0, 0, 0, 0, 1, 1, 1, 1, 0, 1, 1, 1, 1, 0, 0, 0, 1, 1, 0, 0, 1, 0, 0, 0, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1],
"height":10,
"width":10
}
As you can see, this gives a simple 10x10 maze with some dead ends. The player starts in the bottom right corner (my choice, could be anywhere). I rewrote the random platforms code (from Don’s example) to instead loop over the map data and place walls where it is 1 and position the player where data is 2. I set the position so that the origin of the map would be 0,1.5,0. The y axis is in this case the height (ground being 0), but if a wall is positioned at 0 by its centre then some of it is underground. So the y needed to be the height divided by 2.
document.querySelector('a-scene').addEventListener('render-target-loaded', function () {
var WALL_SIZE = 5,
WALL_HEIGHT = 3;
var el = document.querySelector('#walls');
var wall;
for (var x = 0; x < map.height; x++) {
for (var y = 0; y < map.width; y++) {
var i = y*map.width + x;
var position = (x-map.width/2)*WALL_SIZE + ' ' + 1.5 + ' ' + (y-map.height/2)*WALL_SIZE;
if (map.data[i] === 1) {
// Create wall
wall = document.createElement('a-box');
el.appendChild(wall);
wall.setAttribute('color', '#fff');
wall.setAttribute('material', 'src: #texture-wall;');
wall.setAttribute('width', WALL_SIZE);
wall.setAttribute('height', WALL_HEIGHT);
wall.setAttribute('depth', WALL_SIZE);
wall.setAttribute('position', position);
wall.setAttribute('static-body', ');
}
if (map.data[i] === 2) {
// Set player position
document.querySelector('#player').setAttribute('position', position);
}
}
}
console.info('Walls added.');
});
With this added, it makes it nice and easy to change around the map as well as to add new features. Perhaps you want monsters or objects. Just set the number in the map data and add an if statement to the loop. In the future you could add layers, so multiple things can be in the same position. Or perhaps even make the maze go up the y axis too, with ramps or staircases. There’s a lot you can do with relative ease. As you can see, A-Frame really does reduce the learning curve of 3D and VR on the web.
It’s Not All Fun And Games
A lot of examples of virtual reality are games, including this one. So it is understandable to think that VR is for gaming, but actually that’s just a tiny subset. There are all sorts of applications for VR, including story telling, data visualisation and even meditation.
There have been a number of cases where it has been shown virtual reality can help as a tool for therapies:
Oxford study finds virtual reality can help treat severe paranoia
Virtual Reality Therapy for Phobias at the Duke Faculty Practice
Bravemind: Virtual Reality Exposure Therapy at the University of Southern California
These are just a few examples of where virtual reality is being used around the world to help people feel better and get through some very tough times. There have also been examples of it being used for simulating war zones or medical situations, both as a teaching and journalism tool.
Wrapping Up
Ten years ago, on this very site, Cameron Moll wrote an article explaining the mobile web. He explained how mobile phones with data plans were becoming increasingly common, that WAP 2.0 included the XHTML Mobile Profile meaning it would be familiar with web folk. “The mobile web is rapidly becoming an XHTML environment, and thus you and I can apply our existing “desktop web” skills to understand how to develop content for it.”
We can look at that and laugh a little, we have come a very long way in the last decade. Even people in developing countries with very little money have mobile phones with access to a web that is far more capable than the “desktop web” Cameron was referring to.
So while I am not saying virtual reality is going to change the world or replace our phones, who knows! We can use our skills as web folk to dabble, we don’t need to learn any new languages. If on the 2026 edition of 24 ways, somebody references this article and looks at how far we have come… well, let’s hope we have used our skills well and made the world just that little bit better. And if VR is a fad? Well it’s fun… have a go anyway. |
2016 |
Shane Hudson |
shanehudson |
2016-12-11T00:00:00+00:00 |
https://24ways.org/2016/first-steps-in-vr/ |
code |
| 289 |
Front-End Developers Are Information Architects Too |
The theme of this year’s World IA Day was “Information Everywhere, Architects Everywhere”. This article isn’t about what you may consider an information architect to be: someone in the user-experience field, who maybe studied library science, and who talks about taxonomies. This is about a realisation I had a couple of years ago when I started to run an increasing amount of usability-testing sessions with people who have disabilities: that the structure, labelling, and connections that can be made in front-end code is information architecture. People’s ability to be successful online is unequivocally connected to the quality of the code that is written.
Places made of information
In information architecture we talk about creating places made of information. These places are made of ones and zeros, but we talk about them as physical structures. We talk about going onto a social media platform, posting in blogs, getting locked out of an environment, and building applications. In 2002, Andrew Hinton stated:
People live and work in these structures, just as they live and work in their homes, offices, factories and malls. These places are not virtual: they are as real as our own minds.
25 Theses
We’re creating structures which people rely on for significant parts of their lives, so it’s critical that we carry out our work responsibly. This means we must use our construction materials correctly. Luckily, our most important material, HTML, has a well-documented specification which tells us how to build robust and accessible places. What is most important, I believe, is to understand the semantics of HTML.
Semantics
The word “semantic” has its origin in Greek words meaning “significant”, “signify”, and “sign”. In the physical world, a structure can have semantic qualities that tell us something about it. For example, the stunning Westminster Abbey inspires awe and signifies much about the intent and purpose of the structure. The building’s size; the quality of the stone work; the massive, detailed stained glass: these are all signs that this is a building meant for something the creators deemed important. Alternatively consider a set of large, clean, well-positioned, well-lit doors on the ground floor of an office block: they don’t need an “entrance” sign to communicate their use and to stop people trying to use a nearby fire exit to get into the building. The design of the doors signify their usage. Sometimes a more literal and less awe-inspiring approach to communicating a building’s purpose happens, but the affect is similar: the building is signifying something about its purpose.
HTML has over 115 elements, many of which have semantics to signify structure and affordance to people, browsers, and assistive technology. The HTML 5.1 specification mentions semantics, stating:
Elements, attributes, and attribute values in HTML are defined … to have certain meanings (semantics). For example, the <ol> element represents an ordered list, and the lang attribute represents the language of the content.
HTML 5.1 Semantics, structure, and APIs of HTML documents
HTML’s baked-in semantics means that developers can architect their code to signify structure, create relationships between elements, and label content so people can understand what they’re interacting with. Structuring and labelling information to make it available, usable, and understandable to people is what an information architect does. It’s also what a front-end developer does, whether they realise it or not.
A brief introduction to information architecture
We’re going to start by looking at what an information architect is. There are many definitions, and I’m going to quote Richard Saul Wurman, who is widely regarded as the father of information architecture. In 1976 he said an information architect is:
the individual who organizes the patterns inherent in data, making the complex clear; a person who creates the structure or map of information which allows others to find their personal paths to knowledge; the emerging 21st century professional occupation addressing the needs of the age focused upon clarity, human understanding, and the science of the organization of information.
Of Patterns And Structures
To me, this clearly defines any developer who creates code that a browser, or other user agent (for example, a screen reader), uses to create a structured, navigable place for people.
Just as there are many definitions of what an information architect is, there are for information architecture itself. I’m going to use the definition from the fourth edition of Information Architecture For The World Wide Web, in which the authors define it as:
The structural design of shared information environments.
The synthesis of organization, labeling, search, and navigation systems within digital, physical, and cross-channel ecosystems.
The art and science of shaping information products and experiences to support usability, findability, and understanding.
Information Architecture For The World Wide Web, 4th Edition
To me, this describes front-end development. Done properly, there is an art to creating robust, accessible, usable, and findable spaces that delight all our users. For example, at 2015’s State Of The Browser conference, Edd Sowden talked about the accessibility of <table>s. He discovered that by simply not using the semantically-correct <th> element to mark up <table> headings, in some situations browsers will decide that a <table> is being used for layout and essentially make it invisible to assistive technology. Another example of how coding practices can affect the usability and findability of content is shown by Léonie Watson in her How ARIA landmark roles help screen reader users video. By using ARIA landmark roles, people who use screen readers are quickly able to identify and jump to common parts of a web page.
Our definitions of information architects and information architecture mention patterns, rules, organisation, labelling, structure, and relationships. There are numerous different models for how these elements get boiled down to their fundamentals. In his Understanding Context book, Andrew Hinton calls them Labels, Relationships, and Rules; Jorge Arango calls them Links, Nodes, And Order; and Dan Klyn uses Ontology, Taxonomy, and Choreography, which is the one we’re going to use. Dan defines these terms as:
Ontology
The definition and articulation of the rules and patterns that govern the meaning of what we intend to communicate.
What we mean when we say what we say.
Taxonomy
The arrangements of the parts. Developing systems and structures for what everything’s called, where everything’s sorted, and the relationships between labels and categories
Choreography
Rules for interaction among the parts. The structures it creates foster specific types of movement and interaction; anticipating the way users and information want to flow and making affordance for change over time.
We now have definitions of an information architect, information architecture, and a model of the elements of information architecture. But is writing HTML really creating information or is it just wrangling data and metadata? When does data turn into information? In his book Managing For The Future Peter Drucker states:
… data is not information. Information is data endowed with relevance and purpose.
Managing For The Future
If we use the correct semantic element to mark up content then we’re developing with purpose and creating relevance. For example, if we follow the advice of the HTML 5.1 specification and mark up headings using heading rank instead of the outline algorithm, we’re creating a structure where the depth of one heading is relevant to the previous one. Architected correctly, an <h2> element should be relevant to its parent, which should be the <h1>. By following the HTML specification we can create a structured, searchable, labeled document that will hopefully be relevant to what our users need to be successful. If you’ve never used a screen reader, you might be wondering how the headings on a page are searchable. Screen readers give users the ability to interact with headings in a couple of ways:
by creating a list of headings so users can quickly scan the page for information
by using a keyboard command to cycle through one heading at a time
If we had a document for Christmas Day TV we might structure it something like this:
<h1>Christmas Day TV schedule</h1>
<h2>BBC1</h2>
<h3>Morning</h3>
<h3>Evening</h3>
<h2>BBC2</h2>
<h3>Morning</h3>
<h3>Evening</h3>
<h2>ITV</h2>
<h3>Morning</h3>
<h3>Evening</h3>
<h2>Channel 4</h2>
<h3>Morning</h3>
<h3>Evening</h3>
If I use VoiceOver to generate a list of headings, I get this:
Once I have that list I can use keyboard commands to filter the list based on the heading level. For example, I can press 2 to hear just the <h2>s:
If we hadn’t used headings, of if we’d nested them incorrectly, our users would be frustrated.
Putting this together
Let’s put this together with an example of a button that, when pressed, toggles the appearance of a panel of links. There are numerous ways we could create a button on a web page, but the best way is to just use a <button>. Every browser understands what a <button> is, how it works, and what keyboard shortcuts should be used with them. The HTML specification for the <button> element says:
The <button> element represents a button labeled by its contents.
The contents that a <button> can have include the type attribute, any relevant ARIA attributes, and the actual text label that the user sees. This information is more important than the visual design: it doesn’t matter how beautiful or obtuse the design is, if the underlying code is non-semantic and poorly labelled, people are going to struggle to use it. Here are three buttons, each created with the same HTML but with different designs:
Regardless of what they look like, because we’ve used semantic HTML instead of a bunch of meaningless <div>s or <span>s, people who use assistive technology are going to benefit. Out of the box, without any extra development effort, a <button> is accessible and usable with a keyboard. We don’t have to write event handlers to listen for people pressing the Enter key or the space bar, which we would have to do if we’d faked a button with non-semantic elements. Our <button> can also be quickly findable: for example, in the same way it’s possible to create a list of headings with a screen reader, I can also create a list of form elements and then quickly jump to the one I want.
Now we have our <button>, let’s add the panel we’re toggling the appearance of. Here’s our code:
<button aria-controls="panel" aria-expanded="false" class="settings" id="settings" type="button">Settings</button>
<div class="panel hidden" id="panel">
<ul aria-labelledby="settings">
<li><a href="…">Account</a></li>
<li><a href="…">Privacy</a></li>
<li><a href="…">Security</a></li>
</ul>
</div>
There’s quite a bit going on here. We’re using the:
aria-controls attribute to architect a connection between the <button> element and the panel whose appearance it controls. When some assistive technology, for example the JAWS screen reader, encounters an element with aria-controls it audibly tells a user about the controlled expanded element and gives them the ability to move focus to it.
aria-expanded attribute to denote whether the panel is visible or not. We toggle this value using JavaScript to true when the panel is visible and false when it’s not. This important attribute tells people who use screen readers about the state of the elements they’re interacting with. For example, VoiceOver announces Settings expanded button when the panel is visible and Settings collapsed button when it’s hidden.
aria-labelledby attribute to give the list a title of “Settings”. This can benefit some users of assistive technology. For example, screen readers can cycle through all the lists on a page, so being able to title them can improve findability. Being able to hear list Settings three items is, I’d argue, more useful than list three items. By doing this we’re supporting usability and findability.
<ul> element to contain our list of links in our panel.
Let’s look at the choice of <ul> to contain our settings choices. Firstly, our settings are related items, so they belong in a structure that semantically groups things. This is something that a list can do that other elements or patterns can’t. This pattern, for example, isn’t semantic and has no structure:
<div><a href="…">Account</a></div>
<div><a href="…">Privacy</a></div>
<div><a href="…">Security</a></div>
All we have there is three elements next to each other on the screen and in the DOM. That is not robust code that signifies anything.
Why are we using an unordered list as opposed to an ordered list or a definition list? A quick look at the HTML specification tells us why:
The <ul> element represents a list of items, where the order of the items is not important — that is, where changing the order would not materially change the meaning of the document.
The HTML 5.1 specification’s description of the element
Will the meaning of our document materially change if we moved the order of our links around? Nope. Therefore, I’d argue, we’ve used the correct element to structure our content.
These coding decisions are information architecture
I believe that what we’ve done here is pure information architecture. Going back to Dan Klyn’s model, we’ve practiced ontology by looking at the meaning of what we’re intending to communicate:
we want to communicate there is an interactive element that toggles the appearance of an element on a page so we’ve used one, a <button>, with those semantics.
programmatically we’ve used the type='button' attribute to signify that the button isn’t a menu, reset, or submit element.
visually we’ve designed our <button> look like something that can be interacted with and, importantly, we haven’t removed the focus ring.
we’ve labelled the <button> with the word “Settings” so that our users will hopefully understand what the button is for.
we’ve used an <ul> element to structure and communicate our list of related items.
We’ve also practiced taxonomy by developing systems and structures and creating relationships between our elements:
by connecting the <button> to the panel using the aria-controls attribute we’ve programmatically created a relationship between two elements.
we’ve developed a structure in our elements by labelling our <ul> with the same name as the <button> that controls its appearance.
And finally we’ve practiced choreography by creating elements that foster movement and interaction. We’ve anticipated the way users and information want to flow:
we’ve used a <button> element that is interactive and accessible out of the box.
our aria-controls attribute can help some people who use screen readers move easily from the <button> to the panel it controls.
by toggling the value of the aria-expanded attribute we’ve developed a system that tells assistive technology about the status of the relationship between our elements: the panel is visible or the panel is hidden.
we’ve made sure our information is more usable and findable no matter how our users want or need to interact with it. Regardless of how someone “sees” our work they’re going to be able to use it because we’ve architected multiple ways to access our information.
Information architecture, robust code, and accessibility
The United Nations estimates that around 10% of the world’s population has some form of disability which, at the time of writing, is around 740,000,000 people. That’s a lot of people who rely on well-architected semantic code that can be interpreted by whatever assistive technology they may need to use.
If everyone involved in the creation of our places made of information practiced information architecture it would make satisfying the WCAG 2.0 POUR principles so much easier. Our digital construction practices directly affect the quality of life of millions of people, and we have a responsibility to make technology available to them. In her book How To Make Sense Of Any Mess, Abby Covert states:
If we’re going to be successful in this new world, we need to see information as a workable material and learn to architect it in a way that gets us to our goals.
How To Make Sense Of Any Mess
I believe that the world will be a better place if we start treating front-end development as information architecture. |
2016 |
Francis Storr |
francisstorr |
2016-12-17T00:00:00+00:00 |
https://24ways.org/2016/front-end-developers-are-information-architects-too/ |
code |
| 109 |
Geotag Everywhere with Fire Eagle |
A note from the editors: Since this article was written Yahoo! has retired the Fire Eagle service.
Location, they say, is everywhere. Everyone has one, all of the time. But on the web, it’s taken until this year to see the emergence of location in the applications we use and build.
The possibilities are broad. Increasingly, mobile phones provide SDKs to approximate your location wherever you are, browser extensions such as Loki and Mozilla’s Geode provide browser-level APIs to establish your location from the proximity of wireless networks to your laptop. Yahoo’s Brickhouse group launched Fire Eagle, an ambitious location broker enabling people to take their location from any of these devices or sources, and provide it to a plethora of web services. It enables you to take the location information that only your iPhone knows about and use it anywhere on the web.
That said, this is still a time of location as an emerging technology. Fire Eagle stores your location on the web (protected by application-specific access controls), but to try and give an idea of how useful and powerful your location can be — regardless of the services you use now — today’s 24ways is going to build a bookmarklet to call up your location on demand, in any web application.
Location Support on the Web
Over the past year, the number of applications implementing location features has increased dramatically. Plazes and Brightkite are both full featured social networks based around where you are, whilst Pownce rolled in Fire Eagle support to allow geotagging of all the content you post to their microblogging service. Dipity’s beautiful timeline shows for you moving from place to place and Six Apart’s activity stream for Movable Type started exposing your movements.
The number of services that hook into Fire Eagle will increase as location awareness spreads through the developer community, but you can use your location on other sites indirectly too.
Consider Flickr. Now world renowned for their incredible mapping and places features, geotagging on Flickr started out as a grassroots extension of regular tagging. That same technique can be used to start rolling geotagging in any publishing platform you come across, for any kind of content. Machine-tags (geo:lat= and geo:lon=) and the adr and geo microformats can be used to enhance anything you write with location information.
A crash course in avian inflammability
Fire Eagle is a location store. A broker between services and devices which provide location and those which consume it. It’s a switchboard that controls which pieces of your location different applications can see and use, and keeps hidden anything you want kept private. A blog widget that displays your current location in public can be restricted to display just your current city, whilst a service that provides you with a list of the nearest ATMs will operate better with a precise street address.
Even if your iPhone tells Fire Eagle exactly where you are, consuming applications only see what you want them to see. That’s important for users to realise that they’re in control, but also important for application developers to remember that you cannot rely on having super-accurate information available all the time. You need to build location aware applications which degrade gracefully, because users will provide fuzzier information — either through choice, or through less accurate sources.
Application specific permissions are controlled through an OAuth API. Each application has a unique key, used to request a second, user-specific key that permits access to that user’s information. You store that user key and it remains valid until such a time as the user revokes your application’s access. Unlike with passwords, these keys are unique per application, so revoking the access rights of one application doesn’t break all the others.
Building your first Fire Eagle app; Geomarklet
Fire Eagle’s developer documentation can take you through examples of writing simple applications using server side technologies (PHP, Python). Here, we’re going to write a client-side bookmarklet to make your location available in every site you use. It’s designed to fast-track the experience of having location available everywhere on web, and show you how that can be really handy. Hopefully, this will set you thinking about how location can enhance the new applications you build in 2009.
An oddity of bookmarklets
Bookmarklets (or ‘favlets’, for those of an MSIE persuasion) are a strange environment to program in. Critically, you have no persistent storage available. As such, using token-auth APIs in a static environment requires you to build you application in a slightly strange way; authing yourself in advance and then hardcoding the keys into your script.
Get started
Before you do anything else, go to http://fireeagle.com and log in, get set up if you need to and by all means take a look around. Take a look at the mobile updaters section of the application gallery and perhaps pick out an app that will update Fire Eagle from your phone or laptop.
Once that’s done, you need to register for an application key in the developer section. Head straight to /developer/create and complete the form. Since you’re building a standalone application, choose ‘Auth for desktop applications’ (rather than web applications), and select that you’ll be ‘accessing location’, not updating.
At the end of this process, you’ll have two application keys, a ‘Consumer Key’ and a ‘Consumer Secret’, which look like these:
Consumer Key
luKrM9U1pMnu
Consumer Secret
ZZl9YXXoJX5KLiKyVrMZffNEaBnxnd6M
These keys combined allow your application to make requests to Fire Eagle.
Next up, you need to auth yourself; granting your new application permission to use your location. Because bookmarklets don’t have local storage, you can’t integrate the auth process into the bookmarklet itself — it would have no way of storing the returned key. Instead, I’ve put together a simple web frontend through which you can auth with your application.
Head to Auth me, Amadeus!, enter the application keys you just generated and hit ‘Authorize with Fire Eagle’. You’ll be taken to the Fire Eagle website, just as in regular Fire Eagle applications, and after granting access to your app, be redirected back to Amadeus which will provide you your user tokens. These tokens are used in subsequent requests to read your location.
And, skip to the end…
The process of building the bookmarklet, making requests to Fire Eagle, rendering it to the page and so forth follows, but if you’re the impatient type, you might like to try this out right now. Take your four API keys from above, and drag the following link to your Bookmarks Toolbar; it contains all the code described below. Before you can use it, you need to edit in your own API keys. Open your browser’s bookmark editor and where you find text like ‘YOUR_CONSUMER_KEY_HERE’, swap in the corresponding key you just generated.
Get Location
Bookmarklet Basics
To start on the bookmarklet code, set out a basic JavaScript module-pattern structure:
var Geomarklet = function() {
return ({
callback: function(json) {},
run: function() {}
});
};
Geomarklet.run();
Next we’ll add the keys obtained in the setup step, and also some basic Fire Eagle support objects:
var Geomarklet = function() {
var Keys = {
consumer_key: 'IuKrJUHU1pMnu',
consumer_secret: 'ZZl9YXXoJX5KLiKyVEERTfNEaBnxnd6M',
user_token: 'xxxxxxxxxxxx',
user_secret: 'xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx'
};
var LocationDetail = {
EXACT: 0,
POSTAL: 1,
NEIGHBORHOOD: 2,
CITY: 3,
REGION: 4,
STATE: 5,
COUNTRY: 6
};
var index_offset;
return ({
callback: function(json) {},
run: function() {}
});
};
Geomarklet.run();
The Location Hierarchy
A successful Fire Eagle query returns an object called the ‘location hierarchy’. Depending on the level of detail shared, the index of a particular piece of information in the array will vary. The LocationDetail object maps the array indices of each level in the hierarchy to something comprehensible, whilst the index_offset variable is an adjustment based on the detail of the result returned.
The location hierarchy object looks like this, providing a granular breakdown of a location, in human consumable and machine-friendly forms.
"user": {
"location_hierarchy": [{
"level": 0,
"level_name": "exact",
"name": "707 19th St, San Francisco, CA",
"normal_name": "94123",
"geometry": {
"type": "Point",
"coordinates": [ - 0.2347530752, 67.232323]
},
"label": null,
"best_guess": true,
"id": ,
"located_at": "2008-12-18T00:49:58-08:00",
"query": "q=707%2019th%20Street,%20Sf"
},
{
"level": 1,
"level_name": "postal",
"name": "San Francisco, CA 94114",
"normal_name": "12345",
"woeid": ,
"place_id": "",
"geometry": {
"type": "Polygon",
"coordinates": [],
"bbox": []
},
"label": null,
"best_guess": false,
"id": 59358791,
"located_at": "2008-12-18T00:49:58-08:00"
},
{
"level": 2,
"level_name": "neighborhood",
"name": "The Mission, San Francisco, CA",
"normal_name": "The Mission",
"woeid": 23512048,
"place_id": "Y12JWsKbApmnSQpbQg",
"geometry": {
"type": "Polygon",
"coordinates": [],
"bbox": []
},
"label": null,
"best_guess": false,
"id": 59358801,
"located_at": "2008-12-18T00:49:58-08:00"
},
}
In this case the first object has a level of 0, so the index_offset is also 0.
Prerequisites
To query Fire Eagle we call in some existing libraries to handle the OAuth layer and the Fire Eagle API call. Your bookmarklet will need to add the following scripts into the page:
The SHA1 encryption algorithm
The OAuth wrapper
An extension for the OAuth wrapper
The Fire Eagle wrapper itself
When the bookmarklet is first run, we’ll insert these scripts into the document. We’re also inserting a stylesheet to dress up the UI that will be generated.
If you want to follow along any of the more mundane parts of the bookmarklet, you can download the full source code.
Rendering
This bookmarklet can be extended to support any formatting of your location you like, but for sake of example I’m going to build three common formatters that you’ll find useful for common location scenarios: Sites which already ask for your location; and in publishing systems that accept tags or HTML mark-up.
All the rendering functions are items in a renderers object, so they can be iterated through easily, making it trivial to add new formatting functions as your find new use cases (just add another function to the object).
var renderers = {
geotag: function(user) {
if(LocationDetail.EXACT !== index_offset) {
return false;
}
else {
var coords =
user.location_hierarchy[LocationDetail.EXACT].geometry.coordinates;
return "geo:lat=" + coords[0] + ", geo:lon=" + coords[1];
}
},
city: function(user) {
if(LocationDetail.CITY < index_offset) {
return false;
}
else {
return user.location_hierarchy[LocationDetail.CITY - index_offset].name;
}
}
You should always fail gracefully, and in line with catering to users who choose not to share their location precisely, always check that the location has been returned at the level you require. Geotags are expected to be precise, so if an exact location is unavailable, returning false will tell the rendering aspect of the bookmarklet to ignore the function altogether.
These first two are quite simple, geotag returns geo:lat=-0.2347530752, geo:lon=67.232323 and city returns San Francisco, CA.
This final renderer creates a chunk of HTML using the adr and geo microformats, using all available aspects of the location hierarchy, and can be used to geotag any content you write on your blog or in comments:
html: function(user) {
var geostring = '';
var adrstring = '';
var adr = [];
adr.push('<p class="adr">');
// city
if(LocationDetail.CITY >= index_offset) {
adr.push(
'\n <span class="locality">'
+ user.location_hierarchy[LocationDetail.CITY-index_offset].normal_name
+ '</span>,'
);
}
// county
if(LocationDetail.REGION >= index_offset) {
adr.push(
'\n <span class="region">'
+ user.location_hierarchy[LocationDetail.REGION-index_offset].normal_name
+ '</span>,'
);
}
// locality
if(LocationDetail.STATE >= index_offset) {
adr.push(
'\n <span class="region">'
+ user.location_hierarchy[LocationDetail.STATE-index_offset].normal_name
+ '</span>,'
);
}
// country
if(LocationDetail.COUNTRY >= index_offset) {
adr.push(
'\n <span class="country-name">'
+ user.location_hierarchy[LocationDetail.COUNTRY-index_offset].normal_name
+ '</span>'
);
}
// postal
if(LocationDetail.POSTAL >= index_offset) {
adr.push(
'\n <span class="postal-code">'
+ user.location_hierarchy[LocationDetail.POSTAL-index_offset].normal_name
+ '</span>,'
);
}
adr.push('\n</p>\n');
adrstring = adr.join('');
if(LocationDetail.EXACT === index_offset) {
var coords =
user.location_hierarchy[LocationDetail.EXACT].geometry.coordinates;
geostring = '<p class="geo">'
+'\n <span class="latitude">'
+ coords[0]
+ '</span>;'
+ '\n <span class="longitude">'
+ coords[1]
+ '</span>\n</p>\n';
}
return (adrstring + geostring);
}
Here we check the availability of every level of location and build it into the adr and geo patterns as appropriate. Just as for the geotag function, if there’s no exact location the geo markup won’t be returned.
Finally, there’s a rendering method which creates a container for all this data, renders all the applicable location formats and then displays them in the page for a user to copy and paste. You can throw this together with DOM methods and some simple styling, or roll in some components from YUI or JQuery to handle drawing full featured overlays.
You can see this simple implementation for rendering in the full source code.
Make the call
With a framework in place to render Fire Eagle’s location hierarchy, the only thing that remains is to actually request your location. Having already authed through Amadeus earlier, that’s as simple as instantiating the Fire Eagle JavaScript wrapper and making a single function call. It’s a big deal that whilst a lot of new technologies like OAuth add some complexity and require new knowledge to work with, APIs like Fire Eagle are really very simple indeed.
return {
run: function() {
insert_prerequisites();
setTimeout(
function() {
var fe = new FireEagle(
Keys.consumer_key,
Keys.consumer_secret,
Keys.user_token,
Keys.user_secret
);
var script = document.createElement('script');
script.type = 'text/javascript';
script.src = fe.getUserUrl(
FireEagle.RESPONSE_FORMAT.json,
'Geomarklet.callback'
);
document.body.appendChild(script);
},
2000
);
},
callback: function(json) {
if(json.rsp && 'fail' == json.rsp.stat) {
alert('Error ' + json.rsp.code + ": " + json.rsp.message);
}
else {
index_offset = json.user.location_hierarchy[0].level;
draw_selector(json);
}
}
};
We first insert the prerequisite scripts required for the Fire Eagle request to function, and to prevent trying to instantiate the FireEagle object before it’s been loaded over the wire, the remaining instantiation and request is wrapped inside a setTimeout delay.
We then create the request URL, referencing the Geomarklet.callback callback function and then append the script to the document body — allowing a cross-domain request.
The callback itself is quite simple. Check for the presence and value of rsp.status to test for errors, and display them as required. If the request is successful set the index_offset — to adjust for the granularity of the location hierarchy — and then pass the object to the renderer.
The result? When Geomarklet.run() is called, your location from Fire Eagle is read, and each renderer displayed on the page in an easily copy and pasteable form, ready to be used however you need.
Deploy
The final step is to convert this code into a long string for use as a bookmarklet. Easiest for Mac users is the JavaScript bundle in TextMate — choose Bundles: JavaScript: Copy as Bookmarklet to Clipboard. Then create a new ‘Get Location’ bookmark in your browser of choice and paste in.
Those without TextMate can shrink their code down into a single line by first running their code through the JSLint tool (to ensure the code is free from errors and has all the required semi-colons) and then use a find-and-replace tool to remove line breaks from your code (or even run your code through JSMin to shrink it down).
With the bookmarklet created and added to your bookmarks bar, you can now call up your location on any page at all. Get a feel for a web where your location is just another reliable part of the browsing experience.
Where next?
So, the Geomarklet you’ve been guided through is a pretty simple premise and pretty simple output. But from this base you can start to extend: Add code that will insert each of the location renderings directly into form fields, perhaps, or how about site-specific handlers to add your location tags into the correct form field in Wordpress or Tumblr? Paste in your current location to Google Maps? Or Flickr?
Geomarklet gives you a base to start experimenting with location on your own pages and the sites you browse daily.
The introduction of consumer accessible geo to the web is an adventure of discovery; not so much discovering new locations, but discovering location itself. |
2008 |
Ben Ward |
benward |
2008-12-21T00:00:00+00:00 |
https://24ways.org/2008/geotag-everywhere-with-fire-eagle/ |
code |
| 95 |
Giving Content Priority with CSS3 Grid Layout |
Browser support for many of the modules that are part of CSS3 have enabled us to use CSS for many of the things we used to have to use images for. The rise of mobile browsers and the concept of responsive web design has given us a whole new way of looking at design for the web. However, when it comes to layout, we haven’t moved very far at all. We have talked for years about separating our content and source order from the presentation of that content, yet most of us have had to make decisions on source order in order to get a certain visual layout.
Owing to some interesting specifications making their way through the W3C process at the moment, though, there is hope of change on the horizon. In this article I’m going to look at one CSS module, the CSS3 grid layout module, that enables us to define a grid and place elements on to it. This article comprises a practical demonstration of the basics of grid layout, and also a discussion of one way in which we can start thinking of content in a more adaptive way.
Before we get started, it is important to note that, at the time of writing, these examples work only in Internet Explorer 10. CSS3 grid layout is a module created by Microsoft, and implemented using the -ms prefix in IE10. My examples will all use the -ms prefix, and not include other prefixes simply because this is such an early stage specification, and by the time there are implementations in other browsers there may be inconsistencies. The implementation I describe today may well change, but is also there for your feedback.
If you don’t have access to IE10, then one way to view and test these examples is by signing up for an account with Browserstack – the free trial would give you time to have a look. I have also included screenshots of all relevant stages in creating the examples.
What is CSS3 grid layout?
CSS3 grid layout aims to let developers divide up a design into a grid and place content on to that grid. Rather than trying to fabricate a grid from floats, you can declare an actual grid on a container element and then use that to position the elements inside. Most importantly, the source order of those elements does not matter.
Declaring a grid
We declare a grid using a new value for the display property: display: grid. As we are using the IE10 implementation here, we need to prefix that value: display: -ms-grid;.
Once we have declared our grid, we set up the columns and rows using the grid-columns and grid-rows properties.
.wrapper {
display: -ms-grid;
-ms-grid-columns: 200px 20px auto 20px 200px;
-ms-grid-rows: auto 1fr;
}
In the above example, I have declared a grid on the .wrapper element. I have used the grid-columns property to create a grid with a 200 pixel-wide column, a 20 pixel gutter, a flexible width auto column that will stretch to fill the available space, another 20 pixel-wide gutter and a final 200 pixel sidebar: a flexible width layout with two fixed width sidebars. Using the grid-rows property I have created two rows: the first is set to auto so it will stretch to fill whatever I put into it; the second row is set to 1fr, a new value used in grids that means one fraction unit. In this case, one fraction unit of the available space, effectively whatever space is left.
Positioning items on the grid
Now I have a simple grid, I can pop items on to it. If I have a <div> with a class of .main that I want to place into the second row, and the flexible column set to auto I would use the following CSS:
.content {
-ms-grid-column: 3;
-ms-grid-row: 2;
-ms-grid-row-span: 1;
}
If you are old-school, you may already have realised that we are essentially creating an HTML table-like layout structure using CSS. I found the concept of a table the most helpful way to think about the grid layout module when trying to work out how to place elements.
Creating grid systems
As soon as I started to play with CSS3 grid layout, I wanted to see if I could use it to replicate a flexible grid system like this fluid 16-column 960 grid system.
I started out by defining a grid on my wrapper element, using fractions to make this grid fluid.
.wrapper {
width: 90%;
margin: 0 auto 0 auto;
display: -ms-grid;
-ms-grid-columns: 1fr (4.25fr 1fr)[16];
-ms-grid-rows: (auto 20px)[24];
}
Like the 960 grid system I was using as an example, my grid starts with a gutter, followed by the first actual column, plus another gutter repeated sixteen times. What this means is that if I want to span two columns, as far as the grid layout module is concerned that is actually three columns: two wide columns, plus one gutter. So this needs to be accounted for when positioning items.
I created a CSS class for each positioning option: column position; rows position; and column span. For example:
.grid1 {-ms-grid-column: 2;} /* applying this class positions an item in the first column (the gutter is column 1) */
.grid2 {-ms-grid-column: 4;} /* 2nd column - gutter|column 1|gutter */
.grid3 {-ms-grid-column: 6;} /* 3rd column - gutter|column 1|gutter|column2|gutter */
.row1 {-ms-grid-row:1;}
.row2 {-ms-grid-row:3;}
.row3 {-ms-grid-row:5;}
.colspan1 {-ms-grid-column-span:1;}
.colspan2 {-ms-grid-column-span:3;}
.colspan3 {-ms-grid-column-span:5;}
I could then add multiple classes to each element to set the position on on the grid.
This then gives me a replica of the fluid grid using CSS3 grid layout. To see this working fire up IE10 and view Example 1.
This works, but…
This worked, but isn’t ideal. I considered not showing this stage of my experiment – however, I think it clearly shows how the grid layout module works and is a useful starting point. That said, it’s not an approach I would take in production. First, we have to add classes to our markup that tie an element to a position on the grid. This might not be too much of a problem if we are always going to maintain the sixteen-column grid, though, as I will show you that the real power of the grid layout module appears once you start to redefine the grid, using different grids based on media queries. If you drop to a six-column layout for small screens, positioning items into column 16 makes no sense any more.
Calculating grid position using LESS
As we’ve seen, if you want to use a grid with main columns and gutters, you have to take into account the spacing between columns as well as the actual columns. This means we have to do some calculating every time we place an item on the grid. In my example above I got around this by creating a CSS class for each position, allowing me to think in sixteen rather than thirty-two columns. But by using a CSS preprocessor, I can avoid using all the classes yet still think in main columns.
I’m using LESS for my example. My simple grid framework consists of one simple mixin.
.position(@column,@row,@colspan,@rowspan) {
-ms-grid-column: @column*2;
-ms-grid-row: @row*2-1;
-ms-grid-column-span: @colspan*2-1;
-ms-grid-row-span: @rowspan*2-1;
}
My mixin takes four parameters: column; row; colspan; and rowspan. So if I wanted to place an item on column four, row three, spanning two columns and one row, I would write the following CSS:
.box {
.position(4,3,2,1);
}
The mixin would return:
.box {
-ms-grid-column: 8;
-ms-grid-row: 5;
-ms-grid-column-span: 3;
-ms-grid-row-span: 1;
}
This saves me some typing and some maths. I could also add other prefixed values into my mixin as other browsers started to add support.
We can see this in action creating a new grid. Instead of adding multiple classes to each element, I can add one class; that class uses the mixin to create the position. I have also played around with row spans using my mixin and you can see we end up with a quite complicated arrangement of boxes. Have a look at example two in IE10. I’ve used the JavaScript LESS parser so that you can view the actual LESS that I use. Note that I have needed to escape the -ms prefixed properties with ~"" to get LESS to accept them.
This is looking better. I don’t have direct positioning information on each element in the markup, just a class name – I’ve used grid(x), but it could be something far more semantic. We can now take the example a step further and redefine the grid based on screen width.
Media queries and the grid
This example uses exactly the same markup as the previous example. However, we are now using media queries to detect screen width and redefine the grid using a different number of columns depending on that width.
I start out with a six-column grid, defining that on .wrapper, then setting where the different items sit on this grid:
.wrapper {
width: 90%;
margin: 0 auto 0 auto;
display: ~"-ms-grid"; /* escaped for the LESS parser */
-ms-grid-columns: ~"1fr (4.25fr 1fr)[6]"; /* escaped for the LESS parser */
-ms-grid-rows: ~"(auto 20px)[40]"; /* escaped for the LESS parser */
}
.grid1 { .position(1,1,1,1); }
.grid2 { .position(2,1,1,1); }
/* ... see example for all declarations ... */
Using media queries, I redefine the grid to nine columns when we hit a minimum width of 700 pixels.
@media only screen and (min-width: 700px) {
.wrapper {
-ms-grid-columns: ~"1fr (4.25fr 1fr)[9]";
-ms-grid-rows: ~"(auto 20px)[50]";
}
.grid1 { .position(1,1,1,1); }
.grid2 { .position(2,1,1,1); }
/* ... */
}
Finally, we redefine the grid for 960 pixels, back to the sixteen-column grid we started out with.
@media only screen and (min-width: 940px) {
.wrapper {
-ms-grid-columns:~" 1fr (4.25fr 1fr)[16]";
-ms-grid-rows:~" (auto 20px)[24]";
}
.grid1 { .position(1,1,1,1); }
.grid2 { .position(2,1,1,1); }
/* ... */
}
If you view example three in Internet Explorer 10 you can see how the items reflow to fit the window size. You can also see, looking at the final set of blocks, that source order doesn’t matter. You can pick up a block from anywhere and place it in any position on the grid.
Laying out a simple website
So far, like a toddler on Christmas Day, we’ve been playing with boxes rather than thinking about what might be in them. So let’s take a quick look at a more realistic layout, in order to see why the CSS3 grid layout module can be really useful. At this time of year, I am very excited to get out of storage my collection of odd nativity sets, prompting my family to suggest I might want to open a museum. Should I ever do so, I’ll need a website, and here is an example layout.
As I am using CSS3 grid layout, I can order my source in a logical manner. In this example my document is as follows, though these elements could be in any order I please:
<div class="wrapper">
<div class="welcome">
...
</div>
<article class="main">
...
</article>
<div class="info">
...
</div>
<div class="ads">
...
</div>
</div>
For wide viewports I can use grid layout to create a sidebar, with the important information about opening times on the top righ,t with the ads displayed below it. This creates the layout shown in the screenshot above.
@media only screen and (min-width: 940px) {
.wrapper {
-ms-grid-columns:~" 1fr (4.25fr 1fr)[16]";
-ms-grid-rows:~" (auto 20px)[24]";
}
.welcome {
.position(1,1,12,1);
padding: 0 5% 0 0;
}
.info {
.position(13,1,4,1);
border: 0;
padding:0;
}
.main {
.position(1,2,12,1);
padding: 0 5% 0 0;
}
.ads {
.position(13,2,4,1);
display: block;
margin-left: 0;
}
}
In a floated layout, a sidebar like this often ends up being placed under the main content at smaller screen widths. For my situation this is less than ideal. I want the important information about opening times to end up above the main article, and to push the ads below it. With grid layout I can easily achieve this at the smallest width .info ends up in row two and .ads in row five with the article between.
.wrapper {
display: ~"-ms-grid";
-ms-grid-columns: ~"1fr (4.25fr 1fr)[4]";
-ms-grid-rows: ~"(auto 20px)[40]";
}
.welcome {
.position(1,1,4,1);
}
.info {
.position(1,2,4,1);
border: 4px solid #fff;
padding: 10px;
}
.content {
.position(1,3,4,5);
}
.main {
.position(1,3,4,1);
}
.ads {
.position(1,4,4,1);
}
Finally, as an extra tweak I add in a breakpoint at 600 pixels and nest a second grid on the ads area, arranging those three images into a row when they sit below the article at a screen width wider than the very narrow mobile width but still too narrow to support a sidebar.
@media only screen and (min-width: 600px) {
.ads {
display: ~"-ms-grid";
-ms-grid-columns: ~"20px 1fr 20px 1fr 20px 1fr";
-ms-grid-rows: ~"1fr";
margin-left: -20px;
}
.ad:nth-child(1) {
.position(1,1,1,1);
}
.ad:nth-child(2) {
.position(2,1,1,1);
}
.ad:nth-child(3) {
.position(3,1,1,1);
}
}
View example four in Internet Explorer 10.
This is a very simple example to show how we can use CSS grid layout without needing to add a lot of classes to our document. It also demonstrates how we can mainpulate the content depending on the context in which the user is viewing it.
Layout, source order and the idea of content priority
CSS3 grid layout isn’t the only module that starts to move us away from the issue of visual layout being linked to source order. However, with good support in Internet Explorer 10, it is a nice way to start looking at how this might work. If you look at the grid layout module as something to be used in conjunction with the flexible box layout module and the very interesting CSS regions and exclusions specifications, we have, tantalizingly on the horizon, a powerful set of tools for layout.
I am particularly keen on the potential separation of source order from layout as it dovetails rather neatly into something I spend a lot of time thinking about. As a CMS developer, working on larger scale projects as well as our CMS product Perch, I am interested in how we better enable content editors to create content for the web. In particular, I search for better ways to help them create adaptive content; content that will work in a variety of contexts rather than being tied to one representation of that content.
If the concept of adaptive content is new to you, then Karen McGrane’s presentation Adapting Ourselves to Adaptive Content is the place to start. Karen talks about needing to think of content as chunks, that might be used in many different places, displayed differently depending on context.
I absolutely agree with Karen’s approach to content. We have always attempted to move content editors away from thinking about creating a page and previewing it on the desktop. However at some point content does need to be published as a page, or a collection of content if you prefer, and bits of that content have priority. Particularly in a small screen context, content gets linearized, we can only show so much at a time, and we need to make sure important content rises to the top. In the case of my example, I wanted to ensure that the address information was clearly visible without scrolling around too much. Dropping it with the entire sidebar to the bottom of the page would not have been so helpful, though neither would moving the whole sidebar to the top of the screen so a visitor had to scroll past advertising to get to the article.
If our layout is linked to our source order, then enabling the content editor to make decisions about priority is really hard. Only a system that can do some regeneration of the source order on the server-side – perhaps by way of multiple templates – can allow those kinds of decisions to be made. For larger systems this might be a possibility; for smaller ones, or when using an off-the-shelf CMS, it is less likely to be. Fortunately, any system that allows some form of custom field type can be used to pop a class on to an element, and with CSS grid layout that is all that is needed to be able to target that element and drop it into the right place when the content is viewed, be that on a desktop or a mobile device.
This approach can move us away from forcing editors to think visually. At the moment, I might have to explain to an editor that if a certain piece of content needs to come first when viewed on a mobile device, it needs to be placed in the sidebar area, tying it to a particular layout and design. I have to do this because we have to enforce fairly strict rules around source order to make the mechanics of the responsive design work. If I can instead advise an editor to flag important content as high priority in the CMS, then I can make decisions elsewhere as to how that is displayed, and we can maintain the visual hierarchy across all the different ways content might be rendered.
Why frustrate ourselves with specifications we can’t yet use in production?
The CSS3 grid layout specification is listed under the Exploring section of the list of current work of the CSS Working Group. While discussing a module at this stage might seem a bit pointless if we can’t use it in production work, there is a very real reason for doing so. If those of us who will ultimately be developing sites with these tools find out about them early enough, then we can start to give our feedback to the people responsible for the specification. There is information on the same page about how to get involved with the disussions.
So, if you have a bit of time this holiday season, why not have a play with the CSS3 grid layout module? I have outlined here some of my thoughts on how grid layout and other modules that separate layout from source order can be used in the work that I do. Likewise, wherever in the stack you work, playing with and thinking about new specifications means you can think about how you would use them to enhance your work. Spot a problem? Think that a change to the specification would improve things for a specific use case? Then you have something you could post to www-style to add to the discussion around this module.
All the examples are on CodePen so feel free to play around and fork them. |
2012 |
Rachel Andrew |
rachelandrew |
2012-12-18T00:00:00+00:00 |
https://24ways.org/2012/css3-grid-layout/ |
code |
| 68 |
Grid, Flexbox, Box Alignment: Our New System for Layout |
Three years ago for 24 ways 2012, I wrote an article about a new CSS layout method I was excited about. A specification had emerged, developed by people from the Internet Explorer team, bringing us a proper grid system for the web. In 2015, that Internet Explorer implementation is still the only public implementation of CSS grid layout. However, in 2016 we should be seeing it in a new improved form ready for our use in browsers.
Grid layout has developed hidden behind a flag in Blink, and in nightly builds of WebKit and, latterly, Firefox. By being developed in this way, breaking changes could be safely made to the specification as no one was relying on the experimental implementations in production work.
Another new layout method has emerged over the past few years in a more public and perhaps more painful way. Shipped prefixed in browsers, The flexible box layout module (flexbox) was far too tempting for developers not to use on production sites. Therefore, as changes were made to the specification, we found ourselves with three different flexboxes, and browser implementations that did not match one another in completeness or in the version of specified features they supported.
Owing to the different ways these modules have come into being, when I present on grid layout it is often the very first time someone has heard of the specification. A question I keep being asked is whether CSS grid layout and flexbox are competing layout systems, as though it might be possible to back the loser in a CSS layout competition. The reality, however, is that these two methods will sit together as one system for doing layout on the web, each method playing to certain strengths and serving particular layout tasks.
If there is to be a loser in the battle of the layouts, my hope is that it will be the layout frameworks that tie our design to our markup. They have been a necessary placeholder while we waited for a true web layout system, but I believe that in a few years time we’ll be easily able to date a website to circa 2015 by seeing <div class="row"> or <div class="col-md-3"> in the markup.
In this article, I’m going to take a look at the common features of our new layout systems, along with a couple of examples which serve to highlight the differences between them.
To see the grid layout examples you will need to enable grid in your browser. The easiest thing to do is to enable the experimental web platform features flag in Chrome. Details of current browser support can be found here.
Relationship
Items only become flex or grid items if they are a direct child of the element that has display:flex, display:grid or display:inline-grid applied. Those direct children then understand themselves in the context of the complete layout. This makes many things possible. It’s the lack of relationship between elements that makes our existing layout methods difficult to use. If we float two columns, left and right, we have no way to tell the shorter column to extend to the height of the taller one. We have expended a lot of effort trying to figure out the best way to make full-height columns work, using techniques that were never really designed for page layout.
At a very simple level, the relationship between elements means that we can easily achieve full-height columns. In flexbox:
See the Pen Flexbox equal height columns by rachelandrew (@rachelandrew) on CodePen.
And in grid layout (requires a CSS grid-supporting browser):
See the Pen Grid equal height columns by rachelandrew (@rachelandrew) on CodePen.
Alignment
Full-height columns rely on our flex and grid items understanding themselves as part of an overall layout. They also draw on a third new specification: the box alignment module. If vertical centring is a gift you’d like to have under your tree this Christmas, then this is the box you’ll want to unwrap first.
The box alignment module takes the alignment and space distribution properties from flexbox and applies them to other layout methods. That includes grid layout, but also other layout methods. Once implemented in browsers, this specification will give us true vertical centring of all the things.
Our examples above achieved full-height columns because the default value of align-items is stretch. The value ensured our columns stretched to the height of the tallest. If we want to use our new vertical centring abilities on all items, we would set align-items:center on the container. To align one flex or grid item, apply the align-self property.
The examples below demonstrate these alignment properties in both grid layout and flexbox. The portrait image of Widget the cat is aligned with the default stretch. The other three images are aligned using different values of align-self.
Take a look at an example in flexbox:
See the Pen Flexbox alignment by rachelandrew (@rachelandrew) on CodePen.
And also in grid layout (requires a CSS grid-supporting browser):
See the Pen Grid alignment by rachelandrew (@rachelandrew) on CodePen.
The alignment properties used with CSS grid layout.
Fluid grids
A cornerstone of responsive design is the concept of fluid grids.
“[…]every aspect of the grid—and the elements laid upon it—can be expressed as a proportion relative to its container.”
—Ethan Marcotte, “Fluid Grids”
The method outlined by Marcotte is to divide the target width by the context, then use that value as a percentage value for the width property on our element.
h1 {
margin-left: 14.575%; /* 144px / 988px = 0.14575 */
width: 70.85%; /* 700px / 988px = 0.7085 */
}
In more recent years, we’ve been able to use calc() to simplify this (at least, for those of us able to drop support for Internet Explorer 8). However, flexbox and grid layout make fluid grids simple.
The most basic of flexbox demos shows this fluidity in action. The justify-content property – another property defined in the box alignment module – can be used to create an equal amount of space between or around items. As the available width increases, more space is assigned in proportion.
In this demo, the list items are flex items due to display:flex being added to the ul. I have given them a maximum width of 250 pixels. Any remaining space is distributed equally between the items as the justify-content property has a value of space-between.
See the Pen Flexbox: justify-content by rachelandrew (@rachelandrew) on CodePen.
For true fluid grid-like behaviour, your new flexible friends are flex-grow and flex-shrink. These properties give us the ability to assign space in proportion.
The flexbox flex property is a shorthand for:
flex-grow
flex-shrink
flex-basis
The flex-basis property sets the default width for an item. If flex-grow is set to 0, then the item will not grow larger than the flex-basis value; if flex-shrink is 0, the item will not shrink smaller than the flex-basis value.
flex: 1 1 200px: a flexible box that can grow and shrink from a 200px basis.
flex: 0 0 200px: a box that will be 200px and cannot grow or shrink.
flex: 1 0 200px: a box that can grow bigger than 200px, but not shrink smaller.
In this example, I have a set of boxes that can all grow and shrink equally from a 100 pixel basis.
See the Pen Flexbox: flex-grow by rachelandrew (@rachelandrew) on CodePen.
What I would like to happen is for the first element, containing a portrait image, to take up less width than the landscape images, thus keeping it more in proportion. I can do this by changing the flex-grow value. By giving all the items a value of 1, they all gain an equal amount of the available space after the 100 pixel basis has been worked out.
If I give them all a value of 3 and the first box a value of 1, the other boxes will be assigned three parts of the available space while box 1 is assigned only one part. You can see what happens in this demo:
See the Pen Flexbox: flex-grow by rachelandrew (@rachelandrew) on CodePen.
Once you understand flex-grow, you should easily be able to grasp how the new fraction unit (fr, defined in the CSS grid layout specification) works. Like flex-grow, this unit allows us to assign available space in proportion. In this case, we assign the space when defining our track sizes.
In this demo (which requires a CSS grid-supporting browser), I create a four-column grid using the fraction unit to define my track sizes. The first track is 1fr in width, and the others 2fr.
grid-template-columns: 1fr 2fr 2fr 2fr;
See the Pen Grid fraction units by rachelandrew (@rachelandrew) on CodePen.
The four-track grid.
Separation of concerns
My younger self petitioned my peers to stop using tables for layout and to move to CSS. One of the rallying cries of that movement was the concept of separating our source and content from how they were displayed. It was something of a failed promise given the tools we had available: the display leaked into the markup with the need for redundant elements to cope with browser bugs, or visual techniques that just could not be achieved without supporting markup.
Browsers have improved, but even now we can find ourselves compromising the ideal document structure so we can get the layout we want at various breakpoints. In some ways, the situation has returned to tables-for-layout days. Many of the current grid frameworks rely on describing our layout directly in the markup. We add divs for rows, and classes to describe the number of desired columns. We nest these constructions of divs inside one another.
Here is a snippet from the Bootstrap grid examples – two columns with two nested columns:
<div class="row">
<div class="col-md-8">
.col-md-8
<div class="row">
<div class="col-md-6">
.col-md-6
</div>
<div class="col-md-6">
.col-md-6
</div>
</div>
</div>
<div class="col-md-4">
.col-md-4
</div>
</div>
Not a million miles away from something I might have written in 1999.
<table>
<tr>
<td class="col-md-8">
.col-md-8
<table>
<tr>
<td class="col-md-6">
.col-md-6
</td>
<td class="col-md-6">
.col-md-6
</td>
</tr>
</table>
</td>
<td class="col-md-4">
.col-md-4
</td>
</tr>
</table>
Grid and flexbox layouts do not need to be described in markup. The layout description happens entirely in the CSS, meaning that elements can be moved around from within the presentation layer.
Flexbox gives us the ability to reverse the flow of elements, but also to set the order of elements with the order property. This is demonstrated here, where Widget the cat is in position 1 in the source, but I have used the order property to display him after the things that are currently unimpressive to him.
See the Pen Flexbox: order by rachelandrew (@rachelandrew) on CodePen.
Grid layout takes this a step further. Where flexbox lets us set the order of items in a single dimension, grid layout gives us the ability to position things in two dimensions: both rows and columns. Defined in the CSS, this positioning can be changed at any breakpoint without needing additional markup. Compare the source order with the display order in this example (requires a CSS grid-supporting browser):
See the Pen Grid positioning in two dimensions by rachelandrew (@rachelandrew) on CodePen.
Laying out our items in two dimensions using grid layout.
As these demos show, a straightforward way to decide if you should use grid layout or flexbox is whether you want to position items in one dimension or two. If two, you want grid layout.
A note on accessibility and reordering
The issues arising from this powerful ability to change the way items are ordered visually from how they appear in the source have been the subject of much discussion. The current flexbox editor’s draft states
“Authors must use order only for visual, not logical, reordering of content. Style sheets that use order to perform logical reordering are non-conforming.”
—CSS Flexible Box Layout Module Level 1, Editor’s Draft (3 December 2015)
This is to ensure that non-visual user agents (a screen reader, for example) can rely on the document source order as being correct. Take care when reordering that you do so from the basis of a sound document that makes sense in terms of source order. Avoid using visual order to convey meaning.
Automatic content placement with rules
Having control over the order of items, or placing items on a predefined grid, is nice. However, we can often do that already with one method or another and we have frameworks and tools to help us. Tools such as Susy mean we can even get away from stuffing our markup full of grid classes. However, our new layout methods give us some interesting new possibilities.
Something that is useful to be able to do when dealing with content coming out of a CMS or being pulled from some other source, is to define a bunch of rules and then say, “Display this content, using these rules.”
As an example of this, I will leave you with a Christmas poem displayed in a document alongside Widget the cat and some of the decorations that are bringing him no Christmas cheer whatsoever.
The poem is displayed first in the source as a set of paragraphs. I’ve added a class identifying each of the four paragraphs but they are displayed in the source as one text. Below that are all my images, some landscape and some portrait; I’ve added a class of landscape to the landscape ones.
The mobile-first grid is a single column and I use line-based placement to explicitly position my poem paragraphs. The grid layout auto-placement rules then take over and place the images into the empty cells left in the grid.
At wider screen widths, I declare a four-track grid, and position my poem around the grid, keeping it in a readable order.
I also add rules to my landscape class, stating that these items should span two tracks. Once again the grid layout auto-placement rules position the rest of my images without my needing to position them. You will see that grid layout takes items out of source order to fill gaps in the grid. It does this because I have set the property grid-auto-flow to dense. The default is sparse meaning that grid will not attempt this backfilling behaviour.
Take a look and play around with the full demo (requires a CSS grid layout-supporting browser):
See the Pen Grid auto-flow with rules by rachelandrew (@rachelandrew) on CodePen.
The final automatic placement example.
My wish for 2016
I really hope that in 2016, we will see CSS grid layout finally emerge from behind browser flags, so that we can start to use these features in production — that we can start to move away from using the wrong tools for the job.
However, I also hope that we’ll see developers fully embracing these tools as the new system that they are. I want to see people exploring the possibilities they give us, rather than trying to get them to behave like the grid systems of 2015. As you discover these new modules, treat them as the new paradigm that they are, get creative with them. And, as you find the edges of possibility with them, take that feedback to the CSS Working Group. Help improve the layout systems that will shape the look of the future web.
Some further reading
I maintain a site of grid layout examples and resources at Grid by Example.
The three CSS specifications I’ve discussed can be found as editor’s drafts: CSS grid, flexbox, box alignment.
I wrote about the last three years of my interest in CSS grid layout, which gives something of a history of the specification.
More examples of box alignment and grid layout.
My presentation at Fronteers earlier this year, in which I explain more about these concepts. |
2015 |
Rachel Andrew |
rachelandrew |
2015-12-15T00:00:00+00:00 |
https://24ways.org/2015/grid-flexbox-box-alignment-our-new-system-for-layout/ |
code |
| 80 |
HTML5 Video Bumpers |
Video is a bigger part of the web experience than ever before. With native browser support for HTML5 video elements freeing us from the tyranny of plugins, and the availability of faster internet connections to the workplace, home and mobile networks, it’s now pretty straightforward to publish video in a way that can be consumed in all sorts of ways on all sorts of different web devices.
I recently worked on a project where the client had shot some dedicated video shorts to publish on their site. They also had some five-second motion graphics produced to top and tail the videos with context and branding. This pretty common requirement is a great idea on the web, where a user might land at your video having followed a link and be viewing a page without much context.
Known as bumpers, these short introduction clips help brand a video and make it look a lot more professional.
Adding bumpers to a video
The simplest way to add bumpers to a video would be to edit them on to the start and end of the video file itself. Cooking the bumpers into the video file is easy, but should you ever want to update them it can become a real headache. If the branding needs updating, for example, you’d need to re-edit and re-encode all your videos. Not a fun task.
What if the bumpers could be added dynamically? That would enable you to use the same bumper for multiple videos (decreasing download time for users who might watch more than one) and to update the bumpers whenever you wanted. You could change them seasonally, update them for special promotions, run different advertising slots, perform multivariate testing, or even target different bumpers to different users.
The trade-off, of course, is that if you dynamically add your bumpers, there’s a chance that a user in a given circumstance might not see the bumper. For example, if the main video feature was uploaded to YouTube, you’d have no way to control the playback. As always, you need to weigh up the pros and cons and make your choice.
HTML5 bumpers
If you wanted to dynamically add bumpers to your HTML5 video, how would you go about it? That was the question I found myself needing to answer for this particular client project.
My initial thought was to treat it just like an image slideshow. If I were building a slideshow that moved between images, I’d use CSS absolute positioning with z-index to stack the images up on top of each other in a pile, with the first image on top. To transition to the second image, I’d use JavaScript to fade the top image out, revealing the second image beneath it.
Now that video is just a native object in the DOM, just like an image, why not do the same? Stack the videos up with the opening bumper on top, listen for the video’s onended event, and fade it out to reveal the main feature behind. Good idea, right?
Wrong
Remember that this is the web. It’s never going to be that easy. The problem here is that many non-desktop devices use native, dedicated video players. Think about watching a video on a mobile phone – when you play the video, the phone often goes full-screen in its native player, leaving the web page behind. There’s no opportunity to fade or switch z-index, as the video isn’t being viewed in the page. Your page is left powerless. Powerless!
So what can we do? What can we control?
Those of us with particularly long memories might recall a time before CSS, when we’d have to use JavaScript to perform image rollovers. As CSS background images weren’t a practical reality, we would use lots of <img> elements, and perform a rollover by modifying the src attribute of the image.
Turns out, this old trick of modifying the source can help us out with video, too. In most cases, modifying the src attribute of a <video> element, or perhaps more likely the src attribute of a source element, will swap from one video to another.
Swappin’ it
Let’s take a deliberately simple example of a super-basic video tag:
<video src="mycat.webm" controls>no fallback coz i is lame, innit.</video>
We could very simply write a script to find all video tags and give them a new src to show our bumper.
<script>
var videos, i, l;
videos = document.getElementsByTagName('video');
for(i=0, l=videos.length; i<l; i++) {
videos[i].setAttribute('src', 'bumper-in.webm');
}
</script>
View the example in a browser with WebM support. You’ll see that the video is swapped out for the opening bumper. Great!
Beefing it up
Of course, we can’t just publish video in one format. In practical use, you need a <video> element with multiple <source> elements containing your different source formats.
<video controls>
<source src="mycat.mp4" type="video/mp4" />
<source src="mycat.webm" type="video/webm" />
<source src="mycat.ogv" type="video/ogg" />
</video>
This time, our script needs to loop through the sources, not the videos. We’ll use a regular expression replacement to swap out the file name while maintaining the correct file extension.
<script>
var sources, i, l, orig;
sources = document.getElementsByTagName('source');
for(i=0, l=sources.length; i<l; i++) {
orig = sources[i].getAttribute('src');
sources[i].setAttribute('src', orig.replace(/(w+).(w+)/, 'bumper-in.$2'));
// reload the video
sources[i].parentNode.load();
}
</script>
The difference this time is that when changing the src of a <source> we need to call the .load() method on the video to get it to acknowledge the change.
See the code in action, this time in a wider range of browsers.
But, my video!
I guess we should get the original video playing again. Keeping the same markup, we need to modify the script to do two things:
Store the original src in a data- attribute so we can access it later
Add an event listener so we can detect the end of the bumper playing, and load the original video back in
As we need to loop through the videos this time to add the event listener, I’ve moved the .load() call into that loop. It’s a bit more efficient to call it only once after modifying all the video’s sources.
<script>
var videos, sources, i, l, orig;
sources = document.getElementsByTagName('source');
for(i=0, l=sources.length; i<l; i++) {
orig = sources[i].getAttribute('src');
sources[i].setAttribute('data-orig', orig);
sources[i].setAttribute('src', orig.replace(/(w+).(w+)/, 'bumper-in.$2'));
}
videos = document.getElementsByTagName('video');
for(i=0, l=videos.length; i<l; i++) {
videos[i].load();
videos[i].addEventListener('ended', function(){
sources = this.getElementsByTagName('source');
for(i=0, l=sources.length; i<l; i++) {
orig = sources[i].getAttribute('data-orig');
if (orig) {
sources[i].setAttribute('src', orig);
}
sources[i].setAttribute('data-orig','');
}
this.load();
this.play();
});
}
</script>
Again, view the example to see the bumper play, followed by our spectacular main feature. (That’s my cat, Widget. His interests include sleeping and internet marketing.)
Tidying things up
The final thing to do is add our closing bumper after the main video has played. This involves the following changes:
We need to keep track of whether the src has been changed, so we only play the video if it’s changed. I’ve added the modified variable to track this, and it stops us getting into a situation where the video just loops forever.
Add an else to the event listener, for when the orig is false (so the main feature has been playing) to load in the end bumper. We also check that we’re not already playing the end bumper. Because looping.
<script>
var videos, sources, i, l, orig, current, modified;
sources = document.getElementsByTagName('source');
for(i=0, l=sources.length; i<l; i++) {
orig = sources[i].getAttribute('src');
sources[i].setAttribute('data-orig', orig);
sources[i].setAttribute('src', orig.replace(/(w+).(w+)/, 'bumper-in.$2'));
}
videos = document.getElementsByTagName('video');
for(i=0, l=videos.length; i<l; i++) {
videos[i].load();
modified = false;
videos[i].addEventListener('ended', function(){
sources = this.getElementsByTagName('source');
for(i=0, l=sources.length; i<l; i++) {
orig = sources[i].getAttribute('data-orig');
if (orig) {
sources[i].setAttribute('src', orig);
modified = true;
}else{
current = sources[i].getAttribute('src');
if (current.indexOf('bumper-out')==-1) {
sources[i].setAttribute('src', current.replace(/([w]+).(w+)/, 'bumper-out.$2'));
modified = true;
}else{
this.pause();
modified = false;
}
}
sources[i].setAttribute('data-orig','');
}
if (modified) {
this.load();
this.play();
}
});
}
</script>
Yo ho ho, that’s a lot of JavaScript. See it in action – you should get a bumper, the cat video, and an end bumper.
Of course, this code works fine for demonstrating the principle, but it’s very procedural. Nothing wrong with that, but to do something similar in production, you’d probably want to make the code more modular to ease maintainability. Besides, you may want to use a framework, rather than basic JavaScript.
The end credits
One really important principle here is that of progressive enhancement. If the browser doesn’t support JavaScript, the user won’t see your bumper, but they will get the main video. If the browser supports JavaScript but doesn’t allow you to modify the src (as was the case with older versions of iOS), the user won’t see your bumper, but they will get the main video.
If a search engine or social media bot grabs your page and looks for content, they won’t see your bumper, but they will get the main video – which is absolutely what you want.
This means that if the bumper is absolutely crucial, you may still need to cook it into the video. However, for many applications, running it dynamically can work quite well.
As always, it comes down to three things:
Measure your audience: know how people access your site
Test the solution: make sure it works for your audience
Plan for failure: it’s the web and that’s how things work ‘round these parts
But most of all play around with it, have fun and build something awesome. |
2012 |
Drew McLellan |
drewmclellan |
2012-12-01T00:00:00+00:00 |
https://24ways.org/2012/html5-video-bumpers/ |
code |
| 177 |
HTML5: Tool of Satan, or Yule of Santa? |
It would lead to unseasonal arguments to discuss the title of this piece here, and the arguments are as indigestible as the fourth turkey curry of the season, so we’ll restrict our article to the practical rather than the philosophical: what HTML5 can you reasonably expect to be able to use reliably cross-browser in the early months of 2010?
The answer is that you can use more than you might think, due to the seasonal tinsel of feature-detection and using the sparkly pixie-dust of IE-only VML (but used in a way that won’t damage your Elf).
Canvas
canvas is a 2D drawing API that defines a blank area of the screen of arbitrary size, and allows you to draw on it using JavaScript. The pictures can be animated, such as in this canvas mashup of Wolfenstein 3D and Flickr. (The difference between canvas and SVG is that SVG uses vector graphics, so is infinitely scalable. It also keeps a DOM, whereas canvas is just pixels so you have to do all your own book-keeping yourself in JavaScript if you want to know where aliens are on screen, or do collision detection.)
Previously, you needed to do this using Adobe Flash or Java applets, requiring plugins and potentially compromising keyboard accessibility. Canvas drawing is supported now in Opera, Safari, Chrome and Firefox. The reindeer in the corner is, of course, Internet Explorer, which currently has zero support for canvas (or SVG, come to that).
Now, don’t pull a face like all you’ve found in your Yuletide stocking is a mouldy satsuma and a couple of nuts—that’s not the end of the story. Canvas was originally an Apple proprietary technology, and Internet Explorer had a similar one called Vector Markup Language which was submitted to the W3C for standardisation in 1998 but which, unlike canvas, was not blessed with retrospective standardisation.
What you need, then, is some way for Internet Explorer to translate canvas to VML on-the-fly, while leaving the other, more standards-compliant browsers to use the HTML5. And such a way exists—it’s a JavaScript library called excanvas. It’s downloadable from http://code.google.com/p/explorercanvas/ and it’s simple to include it via a conditional comment in the head for IE:
<!--[if IE]>
<script src="excanvas.js"></script>
<![endif]-->
Simply include this, and your canvas will be natively supported in the modern browsers (and the library won’t even be downloaded) whereas IE will suddenly render your canvas using its own VML engine. Be sure, however, to check it carefully, as the IE JavaScript engine isn’t so fast and you’ll need to be sure that performance isn’t too degraded to use.
Forms
Since the beginning of the Web, developers have been coding forms, and then writing JavaScript to check whether an input is a correctly formed email address, URL, credit card number or conforms to some other pattern. The cumulative labour of the world’s developers over the last 15 years makes whizzing round in a sleigh and delivering presents seem like popping to the corner shop in comparison.
With HTML5, that’s all about to change. As Yaili began to explore on Day 3, a host of new attributes to the input element provide built-in validation for email address formats (input type=email), URLs (input type=url), any pattern that can be expressed with a JavaScript-syntax regex (pattern="[0-9][A-Z]{3}") and the like. New attributes such as required, autofocus, input type=number min=3 max=50 remove much of the tedious JavaScript from form validation.
Other, really exciting input types are available (see all input types). The datalist is reminiscent of a select box, but allows the user to enter their own text if they don’t want to choose one of the pre-defined options. input type=range is rendered as a slider, while input type=date pops up a date picker, all natively in the browser with no JavaScript required at all.
Currently, support is most complete in an experimental implementation in Opera and a number of the new attributes in Webkit-based browsers. But don’t let that stop you! The clever thing about the specification of the new Web Forms is that all the new input types are attributes (rather than elements). input defaults to input type=text, so if a browser doesn’t understand a new HTML5 type, it gracefully degrades to a plain text input.
So where does that leave validation in those browsers that don’t support Web Forms? The answer is that you don’t retire your pre-existing JavaScript validation just yet, but you leave it as a fallback after doing some feature detection. To detect whether (say) input type=email is supported, you make a new input type=email with JavaScript but don’t add it to the page. Then, you interrogate your new element to find out what its type attribute is. If it’s reported back as “email”, then the browser supports the new feature, so let it do its work and don’t bring in any JavaScript validation. If it’s reported back as “text”, it’s fallen back to the default, indicating that it’s not supported, so your code should branch to your old validation routines. Alternatively, use the small (7K) Modernizr library which will do this work for you and give you JavaScript booleans like Modernizr.inputtypes[email] set to true or false.
So what does this buy you? Well, first and foremost, you’re future-proofing your code for that time when all browsers support these hugely useful additions to forms. Secondly, you buy a usability and accessibility win. Although it’s tempting to style the stuffing out of your form fields (which can, incidentally, lead to madness), whatever your branding people say, it’s better to leave forms as close to the browser defaults as possible. A browser’s slider and date pickers will be the same across different sites, making it much more comprehensible to users. And, by using native controls rather than faking sliders and date pickers with JavaScript, your forms are much more likely to be accessible to users of assistive technology.
HTML5 DOCTYPE
You can use the new DOCTYPE !doctype html now and – hey presto – you’re writing HTML5, as it’s pretty much a superset of HTML4. There are some useful advantages to doing this. The first is that the HTML5 validator (I use http://html5.validator.nu) also validates ARIA information, whereas the HTML4 validator doesn’t, as ARIA is a new spec developed after HTML4. (Actually, it’s more accurate to say that it doesn’t validate your ARIA attributes, but it doesn’t automatically report them as an error.)
Another advantage is that HTML5 allows tabindex as a global attribute (that is, on any element). Although originally designed as an accessibility bolt-on, I ordinarily advise you don’t use it; a well-structured page should provide a logical tab order through links and form fields already.
However, tabindex="-1" is a legal value in HTML5 as it allows for the element to be programmatically focussable by JavaScript. It’s also very useful for correcting a bug in Internet Explorer when used with a keyboard; in-page links go nowhere if the destination doesn’t have a proprietary property called hasLayout set or a tabindex of -1.
So, whether it is the tool of Satan or yule of Santa, HTML5 is just around the corner. Some you can use now, and by the end of 2010 I predict you’ll be able to use a whole lot more as new browser versions are released. |
2009 |
Bruce Lawson |
brucelawson |
2009-12-05T00:00:00+00:00 |
https://24ways.org/2009/html5-tool-of-satan-or-yule-of-santa/ |
code |
| 121 |
Hide And Seek in The Head |
If you want your JavaScript-enhanced pages to remain accessible and understandable to scripted and noscript users alike, you have to think before you code. Which functionalities are required (ie. should work without JavaScript)? Which ones are merely nice-to-have (ie. can be scripted)? You should only start creating the site when you’ve taken these decisions.
Special HTML elements
Once you have a clear idea of what will work with and without JavaScript, you’ll likely find that you need a few HTML elements for the noscript version only.
Take this example: A form has a nifty bit of Ajax that automatically and silently sends a request once the user enters something in a form field. However, in order to preserve accessibility, the user should also be able to submit the form normally. So the form should have a submit button in noscript browsers, but not when the browser supports sufficient JavaScript.
Since the button is meant for noscript browsers, it must be hard-coded in the HTML:
<input type="submit" value="Submit form" id="noScriptButton" />
When JavaScript is supported, it should be removed:
var checkJS = [check JavaScript support];
window.onload = function () {
if (!checkJS) return;
document.getElementById('noScriptButton').style.display = 'none';
}
Problem: the load event
Although this will likely work fine in your testing environment, it’s not completely correct. What if a user with a modern, JavaScript-capable browser visits your page, but has to wait for a huge graphic to load? The load event fires only after all assets, including images, have been loaded. So this user will first see a submit button, but then all of a sudden it’s removed. That’s potentially confusing.
Fortunately there’s a simple solution: play a bit of hide and seek in the <head>:
var checkJS = [check JavaScript support];
if (checkJS) {
document.write('<style>#noScriptButton{display: none}</style>');
}
First, check if the browser supports enough JavaScript. If it does, document.write an extra <style> element that hides the button.
The difference with the previous technique is that the document.write command is outside any function, and is therefore executed while the JavaScript is being parsed. Thus, the #noScriptButton{display: none} rule is written into the document before the actual HTML is received.
That’s exactly what we want. If the rule is already present at the moment the HTML for the submit button is received and parsed, the button is hidden immediately. Even if the user (and the load event) have to wait for a huge image, the button is already hidden, and both scripted and noscript users see the interface they need, without any potentially confusing flashes of useless content.
In general, if you want to hide content that’s not relevant to scripted users, give the hide command in CSS, and make sure it’s given before the HTML element is loaded and parsed.
Alternative
Some people won’t like to use document.write. They could also add an empty <link /> element to the <head> and give it an href attribute once the browser’s JavaScript capabilities have been evaluated. The <link /> element is made to refer to a style sheet that contains the crucial #noScriptButton{display: none}, and everything works fine.
Important note: The script needs access to the <link />, and the only way to ensure that access is to include the empty <link /> element before your <script> tag. |
2006 |
Peter-Paul Koch |
ppk |
2006-12-06T00:00:00+00:00 |
https://24ways.org/2006/hide-and-seek-in-the-head/ |
code |
| 55 |
How Tabs Should Work |
Tabs in browsers (not browser tabs) are one of the oldest custom UI elements in a browser that I can think of. They’ve been done to death. But, sadly, most of the time I come across them, the tabs have been badly, or rather partially, implemented.
So this post is my definition of how a tabbing system should work, and one approach of implementing that.
But… tabs are easy, right?
I’ve been writing code for tabbing systems in JavaScript for coming up on a decade, and at one point I was pretty proud of how small I could make the JavaScript for the tabbing system:
var tabs = $('.tab').click(function () {
tabs.hide().filter(this.hash).show();
}).map(function () {
return $(this.hash)[0];
});
$('.tab:first').click();
Simple, right? Nearly fits in a tweet (ignoring the whole jQuery library…). Still, it’s riddled with problems that make it a far from perfect solution.
Requirements: what makes the perfect tab?
All content is navigable and available without JavaScript (crawler-compatible and low JS-compatible).
ARIA roles.
The tabs are anchor links that:
are clickable
have block layout
have their href pointing to the id of the panel element
use the correct cursor (i.e. cursor: pointer).
Since tabs are clickable, the user can open in a new tab/window and the page correctly loads with the correct tab open.
Right-clicking (and Shift-clicking) doesn’t cause the tab to be selected.
Native browser Back/Forward button correctly changes the state of the selected tab (think about it working exactly as if there were no JavaScript in place).
The first three points are all to do with the semantics of the markup and how the markup has been styled. I think it’s easy to do a good job by thinking of tabs as links, and not as some part of an application. Links are navigable, and they should work the same way other links on the page work.
The last three points are JavaScript problems. Let’s investigate that.
The shitmus test
Like a litmus test, here’s a couple of quick ways you can tell if a tabbing system is poorly implemented:
Change tab, then use the Back button (or keyboard shortcut) and it breaks
The tab isn’t a link, so you can’t open it in a new tab
These two basic things are, to me, the bare minimum that a tabbing system should have.
Why is this important?
The people who push their so-called native apps on users can’t have more reasons why the web sucks. If something as basic as a tab doesn’t work, obviously there’s more ammo to push a closed native app or platform on your users.
If you’re going to be a web developer, one of your responsibilities is to maintain established interactivity paradigms. This doesn’t mean don’t innovate. But it does mean: stop fucking up my scrolling experience with your poorly executed scroll effects. </rant> :breath:
URI fragment, absolute URL or query string?
A URI fragment (AKA the # hash bit) would be using mysite.com/config#content to show the content panel. A fully addressable URL would be mysite.com/config/content. Using a query string (by way of filtering the page): mysite.com/config?tab=content.
This decision really depends on the context of your tabbing system. For something like GitHub’s tabs to view a pull request, it makes sense that the full URL changes.
For our problem though, I want to solve the issue when the page doesn’t do a full URL update; that is, your regular run-of-the-mill tabbing system.
I used to be from the school of using the hash to show the correct tab, but I’ve recently been exploring whether the query string can be used. The biggest reason is that multiple hashes don’t work, and comma-separated hash fragments don’t make any sense to control multiple tabs (since it doesn’t actually link to anything).
For this article, I’ll keep focused on using a single tabbing system and a hash on the URL to control the tabs.
Markup
I’m going to assume subcontent, so my markup would look like this (yes, this is a cat demo…):
<ul class="tabs">
<li><a class="tab" href="#dizzy">Dizzy</a></li>
<li><a class="tab" href="#ninja">Ninja</a></li>
<li><a class="tab" href="#missy">Missy</a></li>
</ul>
<div id="dizzy">
<!-- panel content -->
</div>
<div id="ninja">
<!-- panel content -->
</div>
<div id="missy">
<!-- panel content -->
</div>
It’s important to note that in the markup the link used for an individual tab references its panel content using the hash, pointing to the id on the panel. This will allow our content to connect up without JavaScript and give us a bunch of features for free, which we’ll see once we’re on to writing the code.
URL-driven tabbing systems
Instead of making the code responsive to the user’s input, we’re going to exclusively use the browser URL and the hashchange event on the window to drive this tabbing system. This way we get Back button support for free.
With that in mind, let’s start building up our code. I’ll assume we have the jQuery library, but I’ve also provided the full code working without a library (vanilla, if you will), but it depends on relatively new (polyfillable) tech like classList and dataset (which generally have IE10 and all other browser support).
Note that I’ll start with the simplest solution, and I’ll refactor the code as I go along, like in places where I keep calling jQuery selectors.
function show(id) {
// remove the selected class from the tabs,
// and add it back to the one the user selected
$('.tab').removeClass('selected').filter(function () {
return (this.hash === id);
}).addClass('selected');
// now hide all the panels, then filter to
// the one we're interested in, and show it
$('.panel').hide().filter(id).show();
}
$(window).on('hashchange', function () {
show(location.hash);
});
// initialise by showing the first panel
show('#dizzy');
This works pretty well for such little code. Notice that we don’t have any click handlers for the user and the Back button works right out of the box.
However, there’s a number of problems we need to fix:
The initialised tab is hard-coded to the first panel, rather than what’s on the URL.
If there’s no hash on the URL, all the panels are hidden (and thus broken).
If you scroll to the bottom of the example, you’ll find a “top” link; clicking that will break our tabbing system.
I’ve purposely made the page long, so that when you click on a tab, you’ll see the page scrolls to the top of the tab. Not a huge deal, but a bit annoying.
From our criteria at the start of this post, we’ve already solved items 4 and 5. Not a terrible start. Let’s solve items 1 through 3 next.
Using the URL to initialise correctly and protect from breakage
Instead of arbitrarily picking the first panel from our collection, the code should read the current location.hash and use that if it’s available.
The problem is: what if the hash on the URL isn’t actually for a tab?
The solution here is that we need to cache a list of known panel IDs. In fact, well-written DOM scripting won’t continuously search the DOM for nodes. That is, when the show function kept calling $('.tab').each(...) it was wasteful. The result of $('.tab') should be cached.
So now the code will collect all the tabs, then find the related panels from those tabs, and we’ll use that list to double the values we give the show function (during initialisation, for instance).
// collect all the tabs
var tabs = $('.tab');
// get an array of the panel ids (from the anchor hash)
var targets = tabs.map(function () {
return this.hash;
}).get();
// use those ids to get a jQuery collection of panels
var panels = $(targets.join(','));
function show(id) {
// if no value was given, let's take the first panel
if (!id) {
id = targets[0];
}
// remove the selected class from the tabs,
// and add it back to the one the user selected
tabs.removeClass('selected').filter(function () {
return (this.hash === id);
}).addClass('selected');
// now hide all the panels, then filter to
// the one we're interested in, and show it
panels.hide().filter(id).show();
}
$(window).on('hashchange', function () {
var hash = location.hash;
if (targets.indexOf(hash) !== -1) {
show(hash);
}
});
// initialise
show(targets.indexOf(location.hash) !== -1 ? location.hash : '');
The core of working out which tab to initialise with is solved in that last line: is there a location.hash? Is it in our list of valid targets (panels)? If so, select that tab.
The second breakage we saw in the original demo was that clicking the “top” link would break our tabs. This was due to the hashchange event firing and the code didn’t validate the hash that was passed. Now this happens, the panels don’t break.
So far we’ve got a tabbing system that:
Works without JavaScript.
Supports right-click and Shift-click (and doesn’t select in these cases).
Loads the correct panel if you start with a hash.
Supports native browser navigation.
Supports the keyboard.
The only annoying problem we have now is that the page jumps when a tab is selected. That’s due to the browser following the default behaviour of an internal link on the page. To solve this, things are going to get a little hairy, but it’s all for a good cause.
Removing the jump to tab
You’d be forgiven for thinking you just need to hook a click handler and return false. It’s what I started with. Only that’s not the solution. If we add the click handler, it breaks all the right-click and Shift-click support.
There may be another way to solve this, but what follows is the way I found – and it works. It’s just a bit… hairy, as I said.
We’re going to strip the id attribute off the target panel when the user tries to navigate to it, and then put it back on once the show code starts to run. This change will mean the browser has nowhere to navigate to for that moment, and won’t jump the page.
The change involves the following:
Add a click handle that removes the id from the target panel, and cache this in a target variable that we’ll use later in hashchange (see point 4).
In the same click handler, set the location.hash to the current link’s hash. This is important because it forces a hashchange event regardless of whether the URL actually changed, which prevents the tabs breaking (try it yourself by removing this line).
For each panel, put a backup copy of the id attribute in a data property (I’ve called it old-id).
When the hashchange event fires, if we have a target value, let’s put the id back on the panel.
These changes result in this final code:
/*global $*/
// a temp value to cache *what* we're about to show
var target = null;
// collect all the tabs
var tabs = $('.tab').on('click', function () {
target = $(this.hash).removeAttr('id');
// if the URL isn't going to change, then hashchange
// event doesn't fire, so we trigger the update manually
if (location.hash === this.hash) {
// but this has to happen after the DOM update has
// completed, so we wrap it in a setTimeout 0
setTimeout(update, 0);
}
});
// get an array of the panel ids (from the anchor hash)
var targets = tabs.map(function () {
return this.hash;
}).get();
// use those ids to get a jQuery collection of panels
var panels = $(targets.join(',')).each(function () {
// keep a copy of what the original el.id was
$(this).data('old-id', this.id);
});
function update() {
if (target) {
target.attr('id', target.data('old-id'));
target = null;
}
var hash = window.location.hash;
if (targets.indexOf(hash) !== -1) {
show(hash);
}
}
function show(id) {
// if no value was given, let's take the first panel
if (!id) {
id = targets[0];
}
// remove the selected class from the tabs,
// and add it back to the one the user selected
tabs.removeClass('selected').filter(function () {
return (this.hash === id);
}).addClass('selected');
// now hide all the panels, then filter to
// the one we're interested in, and show it
panels.hide().filter(id).show();
}
$(window).on('hashchange', update);
// initialise
if (targets.indexOf(window.location.hash) !== -1) {
update();
} else {
show();
}
This version now meets all the criteria I mentioned in my original list, except for the ARIA roles and accessibility. Getting this support is actually very cheap to add.
ARIA roles
This article on ARIA tabs made it very easy to get the tabbing system working as I wanted.
The tasks were simple:
Add aria-role set to tab for the tabs, and tabpanel for the panels.
Set aria-controls on the tabs to point to their related panel (by id).
I use JavaScript to add tabindex=0 to all the tab elements.
When I add the selected class to the tab, I also set aria-selected to true and, inversely, when I remove the selected class I set aria-selected to false.
When I hide the panels I add aria-hidden=true, and when I show the specific panel I set aria-hidden=false.
And that’s it. Very small changes to get full sign-off that the tabbing system is bulletproof and accessible.
Check out the final version (and the non-jQuery version as promised).
In conclusion
There’s a lot of tab implementations out there, but there’s an equal amount that break the browsing paradigm and the simple linkability of content. Clearly there’s a special hell for those tab systems that don’t even use links, but I think it’s clear that even in something that’s relatively simple, it’s the small details that make or break the user experience.
Obviously there are corners I’ve not explored, like when there’s more than one set of tabs on a page, and equally whether you should deliver the initial markup with the correct tab selected. I think the answer lies in using query strings in combination with hashes on the URL, but maybe that’s for another year! |
2015 |
Remy Sharp |
remysharp |
2015-12-22T00:00:00+00:00 |
https://24ways.org/2015/how-tabs-should-work/ |
code |
| 308 |
How to Make a Chrome Extension to Delight (or Troll) Your Friends |
If you’re like me, you grew up drawing mustaches on celebrities. Every photograph was subject to your doodling wrath, and your brilliance was taken to a whole new level with computer programs like Microsoft Paint. The advent of digital cameras meant that no one was safe from your handiwork, especially not your friends. And when you finally got your hands on Photoshop, you spent hours maniacally giggling at your artistic genius.
But today is different. You’re a serious adult with important things to do and a reputation to uphold. You keep up with modern web techniques and trends, and have little time for fun other than a random Giphy on Slack… right?
Nope.
If there’s one thing 2016 has taught me, it’s that we—the self-serious, world-changing tech movers and shakers of the universe—haven’t changed one bit from our younger, more delightable selves.
How do I know? This year I created a Chrome extension called Tabby Cat and watched hundreds of thousands of people ditch productivity for randomly generated cats. Tabby Cat replaces your new tab page with an SVG cat featuring a silly name like “Stinky Dinosaur” or “Tiny Potato”. Over time, the cats collect goodies that vary in absurdity from fishbones to lawn flamingos to Raybans. Kids and adults alike use this extension, and analytics show the majority of use happens Monday through Friday from 9-5. The popularity of Tabby Cat has convinced me there’s still plenty of room in our big, grown-up hearts for fun.
Today, we’re going to combine the formula behind Tabby Cat with your intrinsic desire to delight (or troll) your friends, and create a web app that generates your friends with random objects and environments of your choosing. You can publish it as a Chrome extension to replace your new tab, or simply host it as a website and point to it with the New Tab Redirect extension.
Here’s a sneak peek at my final result featuring my partner, my cat, and I in cheerfully weird accessories. Your result will look however you want it to.
Along the way, we’ll cover how to build a Chrome extension that replaces the new tab page, and explore ways to program randomness into your work to create something truly delightful.
What you’ll need
Adobe Illustrator (or a similar illustration program to export PNG)
Some images of your friends
A text editor
Note: This can be as simple or as complex as you want it to be. Most of the application is pre-built so you can focus on kicking back and getting in touch with your creative side. If you want to dive in deeper, you’ll find ways to do it.
Getting started
Download a local copy of the boilerplate for today’s tutorial here, and open it in a text editor. Inside, you’ll find a simple web app that you can run in Chrome.
Open index.html in Chrome. You should see a grey page that says “Noname”.
Open template.pdf in Adobe Illustrator or a similar program that can export PNG. The file contains an artboard measuring 800px x 800px, with a dotted blue outline of a face. This is your template.
Note: We’re using Google Chrome to build and preview this application because the end-result is a Chrome extension. This means that the application isn’t totally cross-browser compatible, but that’s okay.
Step 1: Gather your friends
The first thing to do is choose who your muses are. Since the holidays are upon us, I’d suggest finding inspiration in your family.
Create your artwork
For each person, find an image where their face is pointed as forward as possible. Place the image onto the Artwork layer of the Illustrator file, and line up their face with the template. Then, rename the artboard something descriptive like face_bob. Here’s my crew:
As you can see, my use of the word “family” extends to cats. There’s no judgement here.
Notice that some of my photos don’t completely fill the artboard–that’s fine. The images will be clipped into ovals when they’re rendered in the application.
Now, export your images by following these steps:
Turn the Template layer off and export the images as PNGs.
In the Export dialog, tick the “Use Artboards” checkbox and enter the range with your faces.
Export at 72ppi to keep things running fast.
Save your images into the images/ folder in your project.
Add your images to config.js
Open scripts/config.js. This is where you configure your extension.
Add key value pairs to the faces object. The key should be the person’s name, and the value should be the filepath to the image.
faces: {
leslie: 'images/face_leslie.png',
kyle: 'images/face_kyle.png',
beep: 'images/face_beep.png'
}
The application will choose one of these options at random each time you open a new tab. This pattern is used for everything in the config file. You give the application groups of choices, and it chooses one at random each time it loads. The only thing that’s special about the faces object is that person’s name will also be displayed when their face is chosen.
Now, when you refresh the project in Chrome, you should see one of your friends along with their name, like this:
Congrats, you’re off and running!
Step 2: Add adjectives
Now that you’ve loaded your friends into the application, it’s time to call them names. This step definitely yields the most laughs for the least amount of effort.
Add a list of adjectives into the prefixes array in config.js. To get the words flowing, I took inspiration from ways I might describe some of my relatives during a holiday gathering…
prefixes: [
'Loving',
'Drunk',
'Chatty',
'Merry',
'Creepy',
'Introspective',
'Cheerful',
'Awkward',
'Unrelatable',
'Hungry',
...
]
When you refresh Chrome, you should see one of these words prefixed before your friend’s name. Voila!
Step 3: Choose your color palette
Real talk: I’m bad at choosing color palettes, so I have a trick up my sleeve that I want to share with you. If you’ve been blessed with the gift of color aptitude, skip ahead.
How to choose colors
To create a color palette, I start by going to a Coolors.co, and I hit the spacebar until I find a palette that I like. We need a wide gamut of hues for our palette, so lock down colors you like and keep hitting the spacebar until you find a nice, full range. You can use as many or as few colors as you like.
Copy these colors into your swatches in Adobe Illustrator. They’ll be the base for any illustrations you create later.
Now you need a set of background colors. Here’s my trick to making these consistent with your illustration palette without completely blending in. Use the “Adjust Palette” tool in Coolors to dial up the brightness a few notches, and the saturation down just a tad to remove any neon effect. These will be your background colors.
Add your background colors to config.js
Copy your hex codes into the bgColors array in config.js.
bgColors: [
'#FFDD77',
'#FF8E72',
'#ED5E84',
'#4CE0B3',
'#9893DA',
...
]
Now when you go back to Chrome and refresh the page, you’ll see your new palette!
Step 4: Accessorize
This is the fun part. We’re going to illustrate objects, accessories, lizards—whatever you want—and layer them on top of your friends.
Your objects will be categorized into groups, and one option from each group will be randomly chosen each time you load the page. Think of a group like “hats” or “glasses”. This will allow combinations of accessories to show at once, without showing two of the same type on the same person.
Create a group of accessories
To get started, open up Illustrator and create a new artboard out of the template. Think of a group of objects that you can riff on. I found hats to be a good place to start. If you don’t feel like illustrating, you can use cut-out images instead.
Next, follow the same steps as you did when you exported the faces. Here they are again:
Turn the Template layer off and export the images as PNGs.
In the Export dialog, tick the “Use Artboards” checkbox and enter the range with your hats.
Export at 72ppi to keep things running fast.
Save your images into the images/ folder in your project.
Add your accessories to config.js
In config.js, add a new key to the customProps object that describes the group of accessories that you just created. Its value should be an array of the filepaths to your images. This is my hats array:
customProps: {
hats: [
'images/hat_crown.png',
'images/hat_santa.png',
'images/hat_tophat.png',
'images/hat_antlers.png'
]
}
Refresh Chrome and behold, accessories!
Create as many more accessories as you want
Repeat the steps above to create as many groups of accessories as you want. I went on to make glasses and hairstyles, so my final illustrator file looks like this:
The last step is adding your new groups to the config object. List your groups in the order that you want them to be stacked in the DOM. My final output will be hair, then hats, then glasses:
customProps: {
hair: [
'images/hair_bowl.png',
'images/hair_bob.png'
],
hats: [
'images/hat_crown.png',
'images/hat_santa.png',
'images/hat_tophat.png',
'images/hat_antlers.png'
],
glasses: [
'images/glasses_aviators.png',
'images/glasses_monacle.png'
]
}
And, there you have it! Randomly generated friends with random accessories.
Feel free to go much crazier than I did. I considered adding a whole group of animals in celebration of the new season of Planet Earth, or even adding Sir David Attenborough himself, or doing a bit of role reversal and featuring the animals with little safari hats! But I digress…
Step 5: Publish it
It’s time to put this in your new tabs! You have two options:
Publish it as a Chrome extension in the Chrome Web Store.
Host it as a website and point to it with the New Tab Redirect extension.
Today, we’re going to cover Option #1 because I want to show you how to make the simplest Chrome extension possible. However, I recommend Option #2 if you want to keep your project private. Every Chrome extension that you publish is made publicly available, so unless your friends want their faces published to an extension that anyone can use, I’d suggest sticking to Option #2.
How to make a simple Chrome extension to replace the new tab page
All you need to do to make your project into a Chrome extension is add a manifest.json file to the root of your project with the following contents. There are plenty of other properties that you can add to your manifest file, but these are the only ones that are required for a new tab replacement:
{
"manifest_version": 2,
"name": "Your extension name",
"version": "1.0",
"chrome_url_overrides" : {
"newtab": "index.html"
}
}
To test your extension, you’ll need to run it in Developer Mode. Here’s how to do that:
Go to the Extensions page in Chrome by navigating to chrome://extensions/.
Tick the checkbox in the upper-right corner labelled “Developer Mode”.
Click “Load unpacked extension…” and select this project.
If everything is running smoothly, you should see your project when you open a new tab. If there are any errors, they should appear in a yellow box on the Extensions page.
Voila! Like I said, this is a very light example of a Chrome extension, but Google has tons of great documentation on how to take things further. Check it out and see what inspires you.
Share the love
Now that you know how to make a new tab extension, go forth and create! But wield your power responsibly. New tabs are opened so often that they’ve become a part of everyday life–just consider how many tabs you opened today. Some people prefer to-do lists in their tabs, and others prefer cats.
At the end of the day, let’s make something that makes us happy. Cheers! |
2016 |
Leslie Zacharkow |
lesliezacharkow |
2016-12-08T00:00:00+00:00 |
https://24ways.org/2016/how-to-make-a-chrome-extension/ |
code |
| 327 |
Improving Form Accessibility with DOM Scripting |
The form label element is an incredibly useful little element – it lets you link the form field unquestionably with the descriptive label text that sits alongside or above it. This is a very useful feature for people using screen readers, but there are some problems with this element.
What happens if you have one piece of data that, for various reasons (validation, the way your data is collected/stored etc), needs to be collected using several form elements?
The classic example is date of birth – ideally, you’ll ask for the date of birth once but you may have three inputs, one each for day, month and year, that you also need to provide hints about the format required. The problem is that to be truly accessible you need to label each field. So you end up needing something to say “this is a date of birth”, “this is the day field”, “this is the month field” and “this is the day field”. Seems like overkill, doesn’t it? And it can uglify a form no end.
There are various ways that you can approach it (and I think I’ve seen them all). Some people omit the label and rely on the title attribute to help the user through; others put text in a label but make the text 1 pixel high and merging in to the background so that screen readers can still get that information. The most common method, though, is simply to set the label to not display at all using the CSS display:none property/value pairing (a technique which, for the time being, seems to work on most screen readers). But perhaps we can do more with this?
The technique I am suggesting as another alternative is as follows (here comes the pseudo-code):
Start with a totally valid and accessible form
Ensure that each form input has a label that is linked to its related form control
Apply a class to any label that you don’t want to be visible (for example superfluous)
Then, through the magic of unobtrusive JavaScript/the DOM, manipulate the page as follows once the page has loaded:
Find all the label elements that are marked as superfluous and hide them
Find out what input element each of these label elements is related to
Then apply a hint about formatting required for input (gleaned from the original, now-hidden label text) – add it to the form input as default text
Finally, add in a behaviour that clears or selects the default text (as you choose)
So, here’s the theory put into practice – a date of birth, grouped using a fieldset, and with the behaviours added in using DOM, and here’s the JavaScript that does the heavy lifting.
But why not just use display:none? As demonstrated at Juicy Studio, display:none seems to work quite well for hiding label elements. So why use a sledge hammer to crack a nut? In all honesty, this is something of an experiment, but consider the following:
Using the DOM, you can add extra levels of help, potentially across a whole form – or even range of forms – without necessarily increasing your markup (it goes beyond simply hiding labels)
Screen readers today may identify a label that is set not to display, but they may not in the future – this might provide a way around
By expanding this technique above, it might be possible to visually change the parent container that groups these items – in this case, a fieldset and legend, which are notoriously difficult to style consistently across different browsers – while still retaining the underlying semantic/logical structure
Well, it’s an idea to think about at least. How is it for you? How else might you use DOM scripting to improve the accessiblity or usability of your forms? |
2005 |
Ian Lloyd |
ianlloyd |
2005-12-03T00:00:00+00:00 |
https://24ways.org/2005/improving-form-accessibility-with-dom-scripting/ |
code |
| 255 |
Inclusive Considerations When Restyling Form Controls |
I would like to begin by saying 2018 was the year that we, as developers, visual designers, browser implementers, and inclusive design and experience specialists rallied together and achieved a long-sought goal: We now have the ability to fully style form controls, across all modern browsers, while retaining their ease of declaration, native functionality and accessibility.
I would like to begin by saying all these things. However, they’re not true. I think we spent the year debating about what file extension CSS should be written in, or something. Or was that last year? Maybe I’m thinking of next year.
Returning to reality, styling form controls is more tricky and time consuming these days rather than flat out “hard”. In fact, depending on the length of the styling-leash a particular browser provides, there are controls you can style quite a bit. As for browsers with shorter leashes, there are other options to force their controls closer to the visual design you’re tasked to match.
However, when striving for custom styled controls, one must be careful not to forget about the inherent functionality and accessibility that many provide. People expect and deserve the products and services they use and pay for to work for them. If these services are visually pleasing, but only function for those who fit the handful of personas they’ve been designed for, then we’ve potentially deprived many people the experiences they deserve.
Quick level setting
Getting down to brass tacks, when creating custom styled form controls that should retain their expected semantics and functionality, we have to consider the following:
Many form elements can be styled directly through standard and browser specific selectors, as well as through some clever styling of markup patterns. We should leverage these native options before reinventing any wheels.
It is important to preserve the underlying semantics of interactive controls. We must not unintentionally exclude people who use assistive technologies (ATs) that rely on these semantics.
Make sure you test what you create. There is a lot of underlying complexity to form controls which may not be immediately apparent if they’re judged solely by their visual presentation in a single browser, or with limited AT testing.
Visually resetting and restyling form controls
Over the course of 2018, I worked on a project where I tested and reported on the accessibility impact of styling various form controls. In conducting my research, I reviewed many of the form controls available in HTML, testing to see how malleable they were to direct styling from standardized CSS selectors.
As I expected, controls such as the various text fields could be restyled rather easily. However, other controls like radio buttons and checkboxes, or sub-elements of special text fields like date, search, and number spinners were resistant to standard-based styling. These particular controls and their sub-elements required specific pseudo-elements to reset and allow for restyling of some of their default presentation.
See the Pen form control styling comparisons by Scott (@scottohara) on CodePen.
https://codepen.io/scottohara/pen/gZOrZm/
Over the years, the ability to directly style form controls has been something many people have clamored for. However, one should realize the benefits of being able to restyle some of these controls may involve more effort than originally anticipated.
If you want to restyle a control from the ground up, then you must also recreate any :active, :focus, and :hover states for the control—all those things that were previously taken care of by browsers. Not only that, but anything you restyle should also work with Windows High Contrast mode, styling for dark mode, and other OS-level settings that browser respect without you even realizing.
You ever try playing with the accessibility settings of your display on macOS, or similar Windows setting?
It is also worth mentioning that any browser prefixed pseudo-elements are not standardized CSS selectors. As MDN mentions at the top of their pages documenting these pseudo-elements:
Non-standard
This feature is non-standard and is not on a standards track. Do not use it on production sites facing the Web: it will not work for every user. There may also be large incompatibilities between implementations and the behavior may change in the future.
While this may be a deterrent for some, it’s my opinion the risks are often only skin-deep. By which I mean if a non-standard selector does change, the control may look a bit quirky, but likely won’t cease to function. A bug report which requires a CSS selector change can be an easy JIRA ticket to close, after all.
Can’t make it? Fake it.
Internet Explorer 11 (IE11) is still neck-and-neck with other browsers in vying for the number 2 spot in desktop browser share. Due to IE not recognizing vendor-prefixed appearance properties, some essential controls like checkboxes won’t render as intended.
Additionally, some controls like select boxes, file uploads, and sub-elements of date fields (calendar popups) cannot be modified by just relying on styling their HTML selectors alone. This means that unless your company designs and develops with a progressive enhancement, or graceful degradation mindset, you’ll need to take a different approach in styling.
Getting clever with markup and CSS
The following CodePen demonstrates how we can create a custom checkbox markup pattern. By mindfully utilizing CSS sibling selectors and positioning of the native control, we can create custom visual styling while also retaining the functionality and accessibility expectations of a native checkbox.
See the Pen Accessible Styled Native Checkbox by Scott (@scottohara) on CodePen.
https://codepen.io/scottohara/pen/RqEayN/
Customizing checkboxes by visually hiding the input and styling well-placed markup with sibling selectors may seem old hat to some. However, many variations of these patterns do not take into account how their method of visually hiding the checkboxes can create discovery issues for certain screen reader navigation methods. For instance, if someone is using a mobile device and exploring by touch, how will they be able to drag their finger over an input that has been reduced to a single pixel, or positioned off screen?
As we move away from the simplicity of declaring a single HTML element and using clever CSS and markup patterns to create restyled form controls, we increase the need for additional testing to ensure no expected behaviors are lost. In other words, what should work in theory may not work in practice when you introduce the various different ways people may engage with a form control. It’s worth remembering: what might be typical interactions for ourselves may be problematic if not impossible for others.
Limitations to cleverness
Creative coding will allow us to apply more consistent custom styles to some of the more problematic form controls. There will be a varied amount of custom markup, CSS, and sometimes JavaScript that will be needed to preserve the control’s inherent usability and accessibility for each control we take this approach to.
However, this method of restyling still doesn’t solve for the lack of feature parity across different browsers. Nor is it a means to account for controls which don’t have a native HTML element equivalent, such as a switch or multi-thumb range slider? Maybe there’s a control that calls for a visual design or proposed user experience that would require too much fighting with a native control’s behavior to be worth the level of effort to implement. Here’s where we need to take another approach.
Using ARIA when appropriate
Sometimes we have no other option than to roll up our sleeves and start building custom form controls from scratch. Fair warning though: just because we’re not leveraging a native HTML control as our foundation, it doesn’t mean we have carte blanche to throw semantics out the window. Enter Accessible Rich Internet Applications (ARIA).
ARIA is a set of attributes that can modify existing elements, or extend HTML to include roles, properties and states that aren’t native to the language. While divs and spans have no meaningful semantic information for us to leverage, with help from the ARIA specification and ARIA Authoring Practices we can incorporate these elements to help create the UI that we need while still following the first rule of Using ARIA:
If you can use a native HTML element or attribute with the semantics and behavior you require already built in, instead of re-purposing an element and adding an ARIA role, state or property to make it accessible, then do so.
By using these documents as guidelines, and testing our custom controls with people of various abilities, we can do our best to make sure a custom control performs as expected for as many people as possible.
Exceptions to the rule
One example of a control that allows for an exception to the first rule of Using ARIA would be a switch control.
Switches and checkboxes are similar components, in that they have both on/checked and off/unchecked states. However, checkboxes are often expected within the context of forms, or used to filter search queries on e-commerce sites. Switches are typically used to instantly enable or deactivate a particular setting at a component or app-based level, as this is their behavior in the native mobile apps in which they were popularized.
While a switch control could be created by visually restyling a checkbox, this does not automatically mean that the underlying semantics and functionality will match the visual representation of the control. For example, the following CodePen restyles checkboxes to look like a switch control, but the semantics of the checkboxes remain which communicate a different way of interacting with the control than what you might expect from a native switch control.
See the Pen Switch Boxes - custom styled checkboxes posing as switches by Scott (@scottohara) on CodePen.
https://codepen.io/scottohara/pen/XyvoeE/
By adding a role="switch" to these checkboxes, we can repurpose the inherent checked/unchecked states of the native control, it’s inherent ability to be focused by Tab key, and Space key to toggle state.
But while this is a valid approach to take in building a switch, how does this actually match up to reality?
Does it pass the test(s)?
Whether deconstructing form controls to fully restyle them, or leveraging them and other HTML elements as a base to expand on, or create, a non-native form control, building it is just the start. We must test that what we’ve restyled or rebuilt works the way people expect it to, if not better.
What we must do here is run a gamut of comparative tests to document the functionality and usability of native form controls. For example:
Is the control implemented in all supported browsers?
If not: where are the gaps? Will it be necessary to implement a custom solution for the situations that degrade to a standard text field?
If so: is each browser’s implementation a good user experience? Is there room for improvement that can be tested against the native baseline?
Test with multiple input devices.
Where the control is implemented, what is the quality of the user experience when using different input devices, such as mouse, touchscreen, keyboard, speech recognition or switch device, to name a few.
You’ll find some HTML5 controls (like date pickers and number spinners) have additional UI elements that may not be announced to AT, or even allow keyboard accessibility. Often these controls can be adjusted by other means, such as text entry, or using arrow keys to increase or decrease values. If restyling or recreating a custom version of a control like these, it may make sense to maintain these native experiences as well.
How well does the control take to custom styles?
If a control can be styled enough to not need to be rebuilt from scratch, that’s great! But make sure that there are no adverse affects on the accessibility of it. For instance, range sliders can be restyled and maintain their functionality and accessibility. However, elements like progress bars can be negatively affected by direct styling.
Always test with different browser and AT pairings to ensure nothing is lost when controls are restyled.
Do specifications match reality?
If recreating controls to get around native limitations, such as the inability to style the options of a select element, or requiring a Switch control which is not native to HTML, do your solutions match user expectations?
For instance, selects have unique picker interfaces on touch devices. And switches have varied levels of support for different browser and screen reader pairings. Test with real people, and check your analytics. If these experiences don’t match people’s expectations, then maybe another solution is in order?
Wrapping up
While styling form controls is definitely easier than it’s ever been, that doesn’t mean that it’s at all simple, nor will it likely ever be. The level of difficulty you’re going to face is going to depend entirely on what it is you’re hoping to style, add-on to, or recreate. And even if you build your custom control exactly to specification, you’ll still be reliant on browsers and assistive technologies being able to fully understand the component they’ve been presented.
Forms and their controls are an incredibly important part of what we need the Internet for. Paying bills, scheduling appointments, ordering groceries, renewing your license or even ordering gifts for the holidays. These are all important tasks that people should be able to complete with as little effort as possible. Especially since for some, completing these tasks online might be their only option.
2018 didn’t end up being the year we got full customization of form controls sorted out. But that’s OK. If we can continue to mindfully work with what we have, and instead challenge ourselves to follow inclusive design principles, well thought out Form Design Patterns, and solve problems with an accessibility first approach, we may come to realize that we can get along just fine without fully branded drop downs.
And hey. There’s always next year, right? |
2018 |
Scott O'Hara |
scottohara |
2018-12-13T00:00:00+00:00 |
https://24ways.org/2018/inclusive-considerations-when-restyling-form-controls/ |
code |
| 91 |
Infinite Canvas: Moving Beyond the Page |
Remember Web 2.0? I do. In fact, that phrase neatly bifurcates my life on the internet. Pre-2.0, I was occupied by chatting on AOL and eventually by learning HTML so I could build sites on Geocities. Around 2002, however, I saw a WYSIWYG demo in Dreamweaver. The instructor was dragging boxes and images around a canvas. With a few clicks he was able to build a dynamic, single-page interface. Coming from the world of tables and inline HTML styles, I was stunned.
As I entered college the next year, the web was blossoming: broadband, Wi-Fi, mobile (proud PDA owner, right here), CSS, Ajax, Bloglines, Gmail and, soon, Google Maps. I was a technology fanatic and a hobbyist web developer. For me, the web had long been informational. It was now rapidly becoming something else, something more: sophisticated, presentational, actionable.
In 2003 we watched as the internet changed. The predominant theme of those early Web 2.0 years was the withering of Internet Explorer 6 and the triumph of web standards. Upon cresting that mountain, we looked around and collectively breathed the rarefied air of pristine HMTL and CSS, uncontaminated by toxic hacks and forks – only to immediately begin hurtling down the other side at what is, frankly, terrifying speed.
Ten years later, we are still riding that rocket. Our days (and nights) are spent cramming for exams on CSS3 and RWD and Sass and RESS. We are the proud, frazzled owners of tiny pocket computers that annihilate the best laptops we could have imagined, and the architects of websites that are no longer restricted to big screens nor even segregated by device. We dragoon our sites into working any time, anywhere. At this point, we can hardly ask the spec developers to slow down to allow us to catch our breath, nor should we. It is, without a doubt, a most wonderful time to be a web developer.
But despite the newfound luxury of rounded corners, gradients, embeddable fonts, low-level graphics APIs, and, glory be, shadows, the canyon between HTML and native appears to be as wide as ever. The improvements in HTML and CSS have, for the most part, been conveniences rather than fundamental shifts. What I’d like to do now, if you’ll allow me, is outline just a few of the remaining gaps that continue to separate web sites and applications from their native companions.
What I’d like for Christmas
There is one irritant which is the grandfather of them all, the one from which all others flow and have their being, and it is, simply, the page refresh. That’s right, the foundational principle of the web is our single greatest foe. To paraphrase a patron saint of designers everywhere, if you see a page refresh, we blew it.
The page refresh brings with it, of course, many noble and lovely benefits: addressability, for one; and pagination, for another. (See also caching, resource loading, and probably half a dozen others.) Still, those concerns can be answered (and arguably answered more compellingly) by replacing the weary page with the young and hearty document. Flash may be dead, but it has many lessons yet to bequeath.
Preparing a single document when the site loads allows us to engage the visitor in a smooth and engrossing experience. We have long known this, of course. Twitter was not the first to attempt, via JavaScript, to envelop the user in a single-page application, nor the first to abandon it. Our shared task is to move those technologies down the stack, to make them more primitive, so that the next Twitter can be built with the most basic combination of HTML and CSS rather than relying on complicated, slow, and unreliable scripted solutions.
So, let’s take a look at what we can do, right now, that we might have a better idea of where our current tools fall short.
A print magazine in HTML clothing
Like many others, I suspect, one of my earliest experiences with publishing was laying out newsletters and newspapers on a computer for print. If you’ve ever used InDesign or Quark or even Microsoft Publisher, you’ll remember reflowing content from page to page. The advent of the internet signaled, in many ways, the abandonment of that model. Articles were no longer constrained by the physical limitations of paper. In shedding our chains, however, it is arguable that we’ve lost something useful. We had a self-contained and complete package, a closed loop. It was a thing that could be handled and finished, and doing so provided a sense of accomplishment that our modern, infinitely scrolling, ever-fractal web of content has stolen.
For our purposes today, we will treat 24 ways as the online equivalent of that newspaper or magazine. A single year’s worth of articles could easily be considered an issue. Right now, navigating between articles means clicking on the article you’d like to view and being taken to that specific address via a page reload. If Drew wanted to, it wouldn’t be difficult to update the page in place (via JavaScript) and change the address (again via JavaScript with the History API) to reflect the new content found at the new location. But what if Drew wanted to do that without JavaScript? And what if he wanted the site to not merely load the content but actually whisk you along the page in a compelling and delightful way, à la the Mag+ demo we all saw a few years ago when the iPad was first introduced? Uh, no.
We’re all familiar with websites that have attempted to go beyond the page by weaving many chunks of content together into a large document and for good reason. There is tremendous appeal in opening and exploring the canvas beyond the edges of our screens.
In one rather straightforward example from last year, Mozilla contacted Full Stop to build a website promoting Aza Raskin’s proposal for a set of Creative Commons-style privacy icons. Like a lot of the sites we build (including our own), the amount of information we were presenting was minimal. In these instances, we encourage our clients to consider including everything on a single page. The result was a horizontally driven site that was, if not whimsical, at least clever and attractive to the intended audience. An experience that is taken for granted when using device-native technology is utterly, maddeningly impossible to replicate on the web without jumping through JavaScript hoops.
In another, more complex example, we again had the pleasure of working with Aza earlier this year, this time on a redesign of the Massive Health website. Our assignment was to design and build a site that communicated Massive’s commitment to modern personal health. The site had to be visually and interactively stunning while maintaining a usable and clear interface for the casual visitor. Our solution was to extend the infinite company logo into a ribbon that carried the visitor through the site narrative. It also meant we’d be asking the browser to accommodate something it was never designed to handle: a non-linear design. (Be sure to play around. There’s a lot going on under the hood. We were also this close to a ZUI, if WebKit didn’t freak out when pages were scaled beyond 10×.) Despite the apparent and deliberate design simplicity, the techniques necessary to implement it are anything but. From updating the URL to moving the visitor from section to section, we’re firmly in JavaScript territory. And that’s a shame.
What can we do?
We might not be able to specify these layouts in HTML and CSS just yet, but that doesn’t mean we can’t learn a few new tricks while we wait. Let’s see how close we can come to recreating the privacy icons design, the Massive design, or the Mag+ design without resorting to JavaScript.
A horizontally paginated site
The first thing we’re going to need is the concept of a page within our HTML document. Using plain old HTML and CSS, we can stack a series of <div>s sideways (with a little assist from our new friend, the viewport-width unit, not that he was strictly necessary). All we need to know is how many pages we have. (And, boy, wouldn’t it be nice to be able to know that without having to predetermine it or use JavaScript?)
.window {
overflow: hidden;
width: 100%;
}
.pages {
width: 200vw;
}
.page {
float: left;
overflow: hidden;
width: 100vw;
}
If you look carefully, you’ll see that the conceit we’ll use in the rest of the demos is in place. Despite the document containing multiple pages, only one is visible at any given time. This allows us to keep the user focused on the task (or content) at hand.
By the way, you’ll need to use a modern, WebKit-based browser for these demos. I recommend downloading the WebKit nightly builds, Chrome Canary, or being comfortable with setting flags in Chrome.
A horizontally paginated site, with transitions
Ah, here’s the rub. We have functional navigation, but precious few cues for the user. It’s not much good shoving the visitor around various parts of the document if they don’t get the pleasant whooshing experience of the journey. You might be thinking, what about that new CSS selector, target-something…? Well, my friend, you’re on the right track. Let’s test it. We’re going to need to use a bit of sleight of hand. While we’d like to simply offset the containing element by the number of pages we’re moving (like we did on Massive), CSS alone can’t give us that information, and that means we’re going to need to fake it by expanding and collapsing pages as you navigate. Here are the bits we’re going to need:
.page {
-webkit-transition: width 1s; // Naturally you're going to want to include all the relevant prefixes here
float: left;
left: 0;
overflow: hidden;
position: relative;
width: 100vw;
}
.page:not(:target) {
width: 0;
}
Ah, but we’re not fooling anyone with that trick. As soon as you move beyond a single page, the visitor’s disbelief comes tumbling down when the linear page transitions are unaffected by the distance the pages are allegedly traveling. And you may have already noticed an even more fatal flaw: I secretly linked you to the first page rather than the unadorned URL. If you visit the same page with no URL fragment, you get a blank screen. Sure, we could force a redirect with some server-side trickery, but that feels like cheating. Perhaps if we had the CSS4 subject selector we could apply styles to the parent based on the child being targeted by the URL. We might also need a few more abilities, like determining the total number of pages and having relative sibling selectors (e.g. nth-sibling), but we’d sure be a lot closer.
A horizontally paginated site, with transitions – no cheating
Well, what other cards can we play? How about the checkbox hack? Sure, it’s a garish trick, but it might be the best we can do today. Check it out.
label {
cursor: pointer;
}
input {
display: none;
}
input:not(:checked) + .page {
max-height: 100vh;
width: 0;
}
Finally, we can see the first page thanks to the state we are able to set on the appropriate radio button. Of course, now we don’t have URLs, so maybe this isn’t a winning plan after all. While our HTML and CSS toolkit may feel primitive at the moment, we certainly don’t want to sacrifice the addressability of the web. If there’s one bedrock principle, that’s it.
A horizontally paginated site, with transitions – no cheating and a gorgeous homepage
Gorgeous may not be the right word, but our little magazine is finally shaping up. Thanks to the CSS regions spec, we’ve got an exciting new power, the ability to begin an article in one place and bend it to our will. (Remember, your everyday browser isn’t going to work for these demos. Try the WebKit nightly build to see what we’re talking about.) As with the rest of the examples, we’re clearly abusing these features. Off-canvas layouts (you can thank Luke Wroblewski for the name) are simply not considered to be normal patterns… yet.
Here’s a quick look at what’s going on:
.excerpt-container {
float: left;
padding: 2em;
position: relative;
width: 100%;
}
.excerpt {
height: 16em;
}
.excerpt_name_article-1,
.page-1 .article-flow-region {
-webkit-flow-from: article-1;
}
.article-content_for_article-1 {
-webkit-flow-into: article-1;
}
The regions pattern is comprised of at least three components: a beginning; an ending; and a source. Using CSS, we’re able to define specific elements that should be available for the content to flow through. If magazine-style layouts are something you’re interested in learning more about (and you should be), be sure to check out the great work Adobe has been doing.
Looking forward, and backward
As designers, builders, and consumers of the web, we share a desire to see the usability and enjoyability of websites continue to rise. We are incredibly lucky to be working in a time when a three-month-old website can be laughably outdated. Our goal ought to be to improve upon both the weaknesses and the strengths of the web platform. We seek not only smoother transitions and larger canvases, but fine-grained addressability. Our URLs should point directly and unambiguously to specific content elements, be they pages, sections, paragraphs or words. Moreover, off-screen design patterns are essential to accommodating and empowering the multitude of devices we use to access the web. We should express the desire that interpage links take advantage of the CSS transitions which have been put to such good effect in every other aspect of our designs. Transitions aren’t just nice to have, they’re table stakes in the highly competitive world of native applications.
The tools and technologies we have right now allow us to create smart, beautiful, useful webpages. With a little help, we can begin removing the seams and sutures that bind the web to an earlier, less sophisticated generation. |
2012 |
Nathan Peretic |
nathanperetic |
2012-12-21T00:00:00+00:00 |
https://24ways.org/2012/infinite-canvas-moving-beyond-the-page/ |
code |
| 295 |
Internet of Stranger Things |
This year I’ve been running a workshop about using JavaScript and Node.js to work with all different kinds of electronics on the Raspberry Pi. So especially for 24 ways I’m going to show you how I made a very special Raspberry Pi based internet connected project! And nothing says Christmas quite like a set of fairy lights connected to another dimension1.
What you’ll see
You can rig up the fairy lights in your home, with the scrawly letters written under each one. The people from the other side (i.e. the internet) will be able to write messages to you from their browser in real time. In fact why not try it now; check this web page. When you click the lights in your browser, my lights (and yours) will turn on and off in real life! (There may be a queue if there are lots of people accessing it, hit the “Send a message” button and wait your turn.)
It’s all done with JavaScript, using Node.js running on both the Raspberry Pi and on the server. I’m using WebSockets to communicate in real time between the browser, server and Raspberry Pi.
What you’ll need
Raspberry Pi any of the following models: Zero (will need straight male header pins soldered2 and Micro USB OTG adaptor), A+, B+, 2, or 3
Micro SD card at least 4Gb Class 10 speed3
Micro USB power supply at least 2A
USB Wifi dongle (unless you have a Pi 3 - that has wifi built in).
Addressable fairy lights
Logic level shifter (with pins soldered unless you want to do it!)
Breadboard
Jumper wires (3x male to male and 4x female to male)
Optional but recommended
Base board to hold the Pi and Breadboard (often comes with a breadboard!)
Find links for where to buy all of these items that goes along with this tutorial. The total price should be around $1004.
Setting up the Raspberry Pi
You’ll need to install the SD card for the Raspberry Pi. You’ll find a link to download a disk image on the support document, ready-made with the Raspbian version of Linux, along with Node.js and all the files you need. Download it and write it to the SD card using the fantastic free software Etcher5.
Next up you have to configure the wifi details on the SD card. If you plug the card into your computer you should see a drive called BOOT. There’s a text file on there called wpa_supplicant.conf. Open it up in your favourite text editor and replace mywifi and mypassword with your wifi details6.
network={
ssid="mywifi"
psk="mypassword"
}
Save the file, eject the card from your computer and plug it into the Raspberry Pi.
If you have a base board or holder for the Raspberry Pi, attach it now. Then connect the wifi USB dongle7 and power supply, but don’t plug it in yet!
Wiring!
Time to wire everything up!
First of all, push the Logic Level Converter into the middle of the breadboard:
Logic Level Converter
The logic level converter may be labelled differently from the one in the diagram but the pins are usually exactly the same internally. I would just make sure the pins marked HV (High Voltage) are on the bottom and LV (Low Voltage) are on the top.
Raspberry Pi pins only output 3.3v but the lights need 5v. That’s why we need the logic level converter in there to boost up the signal.
Connect the first two wires between the Raspberry Pi pins and the breadboard:
Note that the pins on the Raspberry Pi are male, so you need a female to male jumper wire to connect between them and the breadboard. The colours don’t have to match but it’s easier to follow (and check) if you use the same ones as in the diagram.
Then the next two:
This is what you should have so far:
Lights
Now to connect the lights! My ones have a connector with three holes in it that I can push jumper wires into, and hopefully yours will too! So I used the male-to-male jumper wires to connect them to the breadboard.
Make sure that you connect the right end of the lights, mine has a male connector at the wrong end so it’s impossible to do this, but double check.
Also make sure that the holes in the light connector are the same as mine. To do this, follow the wires from the connector to the first light and look at the circuit board inside. You should just about be able to make out the connections labelled + (sometimes 5V, V+ or VCC), GND (or ‘-’ or G) and DI (sometimes DIN for data in).
You can just about make out the +, DI and GND on this picture. Note that on the other side of the board there is a DO for data out - that’s what takes the data along to the chip in the next light. Make sure that you’re plugging into the data-in and not the data-out!
That’s it! Everything’s plugged in and ready to go! But before you plug power into your Pi, double check all your wires and make sure they’re exactly right! You could damage your Raspberry Pi if it is not wired correctly. So triple check!
The Moment of Truth!
Plug in the Raspberry Pi and wait around a minute or two for it to boot up. If all is well, the lights should strobe rainbow colours for one second - that’s your confirmation that it’s connected to my WebSocket server and ready to receive messages from the upside-down!
However, if the first light in the string is pulsing red, it means that you’re not connected to the internet. So check the Troubleshooting section of the support document. If it’s pulsing green then you’re connected to the internet but can’t connect to my server. It must have gone down. Sorry! The code will keep trying so leave it running and maybe it’ll come back up.
Rig up the lights!
Fix the lights up on the wall however you want, pins, nails, tape. I’ve used cable clips. Just be careful! I’m using a 50 light string so I’ve programmed it to use the lights at the end for the letters. That way I have just under half the string to extend down to the floor where I can keep the Raspberry Pi.
Check the photo here to see how the lights line up, note that there are spare unused lights in-between each row:
Now visit lights.seb.ly and you’ll see this :
If you’re the only one online you’ll have direct connection to the lights and any letter you click on will light up both in the browser and in real life. If there are other people there, you’ll need to click the button to join the queue and wait your turn.
How it works - the geeky details!
Electronics:
The pins on the Raspberry Pi are known as GPIO pins, general-purpose input/output. You can connect a wide variety of electronic components to them, LED lights, buttons, switches, and sensors. You can turn the power to the pins on and off using Node.js (or Python, if you prefer).
Addressable LEDs or “Neopixels”
We’re only using one GPIO pin on the Raspberry Pi (the other connections are 5V, 3.3V and ground) and that single pin is controlling all of the lights in the string. The code turns the pin on and off really fast in strictly timed morse-code-like dots and dashes to transmit binary data. The chips attached to each LED decode the binary and adjust the output to the LED accordingly. That chip then sends the data on to the next light in the string.
The chips on each light are the WS2811, part of the WS281x family that come in a multitude of different form factors and are often packaged with tiny LEDs in a single component. They are commonly referred to as Neopixels8 and I used them on my Laser Light Synths project.
Neopixels with the chip and the LED all in one - it’s the white square shaped component and the darker square inside is the chip. These are only 5mm wide!
A Laser Light Synth! Covered with around 800 super bright neopixels!
Logic Level Converter
The logic level converter is a really cheap and easy way to change the level from 3.3v to 5v and back again. You must be careful that you do not connect 5v into a GPIO pin or you will most likely damage the Raspberry Pi processor chip.
Power
Neopixels can often draw a lot of current so you need to be careful how you power them. I’ve measured the current draw from the string to be less than 800mA so you should be fine wired directly to the 5V output. But if you use more lights or have them all on really bright at once, you’ll need to use a separate 5V power supply. If you want to learn more, check out Adafruit’s Neopixel Uberguide.
Node.js
There are two Node.js apps running here, one on the Raspberry Pi and one on my server. You can see the code on my GitHub at github.com/sebleedelisle/stranger-lights for the Raspberry Pi and github.com/sebleedelisle/stranger-lights-server for the server. And they’re hosted on npm as stranger-lights and stranger-lights-server.
The server side code sets up a standard web server to deliver the HTML for the web interface. It also sets up a WebSocket server that allows for real-time communication between the browser and the server. This server code also manages the queue and who is in control of the lights at any given time.
WebSockets
I’m using the excellent Socket.io library to manage the WebSocket connection. Both the browser and the Raspberry Pi Node.js app connects to my WebSocket server.
When you click on a letter in the browser, a message is sent to the server, which forwards it to the connected Raspberry Pi clients and also all the web browsers9.
The Raspberry Pi code
The Node.js app runs automatically on startup, and I made this happen by adding this to the /etc/rc.local file:
node /home/pi/strangerthings/client.js > /dev/null &
Anything in the rc.local file gets executed when the Pi boots up and this line of code runs the Node.js app and routes its output to nowhere (ie /dev/null). The & means that it runs it in the background and doesn’t hold up the boot process.
Working with the Raspberry Pi headless
You might know that when a computer has no screen or keyboard, you would refer to it as “running headless”. So just like most web servers, you need to configure it over the network with ssh10. If you’re on a mac you can find your Pi on the network through the name raspberrypi.local11, otherwise you’ll need to find its IP address. There’s more on the guide to Remote Access instructions on the Raspberry Pi website. And if you’re very new to the terminal, I highly recommend this great online Linux command line tutorial.
Improvements
This is quite an early experiment and I’m sure I’ll discover lots of optimisations over the next few weeks, especially if the server gets a proper hammering today! But there are a few things you can do. Obviously I’ve just rigged up my lights with Post-it notes. It’d be a lot nicer to get a paint brush and try to recreate the Winona-in-a-manic-state text style.
Where next?
Finding quality resources about Node.js for electronics on the Pi can be somewhat hit and miss, but this is getting better all the time. Alternatively I am thinking about running some online courses, please let me know if that’s something you’d be interested in, or sign up to my mailing list at st4i.com.
There are many many more resources for the Raspberry Pi with Python (gpiozero is a good place to start), so if that language works for you, you’ll be spoilt for choice!
Also take a look at Arduino - it’s an incredibly popular platform for electronics and the internet is literally bursting with resources.
I hope you enjoyed this little foray into the world of JavaScript electronics on the Raspberry Pi! If you get this working at home please let me know! Tweet me at @seb_ly.
Not a particularly original idea, but I don’t think I’ve seen anyone do it quite like this before, ie using WebSockets, and Node.js on a Raspberry Pi. Other examples: Internet of Stranger Things, Strangerlights.com, and loads of examples on Instructables ↩︎
Video guide to soldering pins on to a Pi Zero and further soldering advice from Adafruit ↩︎
Slower cards will work but performance may suffer ↩︎
Or £5,000 in UK money. Sorry, Brexit joke :) ↩︎
You will need a card reader on your computer - most micro SD cards come with an adaptor that fits standard SD slots. ↩︎
SSID and password should be all that you need but you can see all the config options on this wpa supplicant guide ↩︎
Raspberry Pi Zero will require the OTG to USB adaptor to attach the wifi dongle ↩︎
Thanks to Adafruit who invented the term neopixels so we don’t have to refer to them as WS281x any more! ↩︎
So you can see other people sending messages in the browser ↩︎
ssh is short for Secure Shell and is a way to connect to a remote computer and type in it just like you would in the terminal. ↩︎
You can change this default hostname using raspi-config ↩︎ |
2016 |
Seb Lee-Delisle |
sebleedelisle |
2016-12-01T00:00:00+00:00 |
https://24ways.org/2016/internet-of-stranger-things/ |
code |
| 126 |
Intricate Fluid Layouts in Three Easy Steps |
The Year of the Script may have drawn attention away from CSS but building fluid, multi-column, cross-browser CSS layouts can still be as unpleasant as a lump of coal. Read on for a worry-free approach in three quick steps.
The layout system I developed, YUI Grids CSS, has three components. They can be used together as we’ll see, or independently.
The Three Easy Steps
Choose fluid or fixed layout, and choose the width (in percents or pixels) of the page.
Choose the size, orientation, and source-order of the main and secondary blocks of content.
Choose the number of columns and how they distribute (for example 50%-50% or 25%-75%), using stackable and nestable grid structures.
The Setup
There are two prerequisites: We need to normalize the size of an em and opt into the browser rendering engine’s Strict Mode.
Ems are a superior unit of measure for our case because they represent the current font size and grow as the user increases their font size setting. This flexibility—the container growing with the user’s wishes—means larger text doesn’t get crammed into an unresponsive container. We’ll use YUI Fonts CSS to set the base size because it provides consistent-yet-adaptive font-sizes while preserving user control.
The second prerequisite is to opt into Strict Mode (more info on rendering modes) by declaring a Doctype complete with URI. You can choose XHTML or HTML, and Transitional or Strict. I prefer HTML 4.01 Strict, which looks like this:
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">
Including the CSS
A single small CSS file powers a nearly-infinite number of layouts thanks to a recursive system and the interplay between the three distinct components. You could prune to a particular layout’s specific needs, but why bother when the complete file weighs scarcely 1.8kb uncompressed? Compressed, YUI Fonts and YUI Grids combine for a miniscule 0.9kb over the wire.
You could save an HTTP request by concatenating the two CSS files, or by adding their contents to your own CSS, but I’ll keep them separate for now:
<link href="fonts.css" rel="stylesheet" type="text/css">
<link href="grids.css" rel="stylesheet" type="text/css">
Example: The Setup
Now we’re ready to build some layouts.
Step 1: Choose Fluid or Fixed Layout
Choose between preset widths of 750px, 950px, and 100% by giving a document-wrapping div an ID of doc, doc2, or doc3. These options cover most use cases, but it’s easy to define a custom fixed width.
The fluid 100% grid (doc3) is what I’ve been using almost exclusively since it was introduced in the last YUI released.
<body>
<div id="doc3"></div>
</body>
All pages are centered within the viewport, and grow with font size. The 100% width page (doc3) preserves 10px of breathing room via left and right margins. If you prefer your content flush to the viewport, just add doc3 {margin:auto} to your CSS.
Regardless of what you choose in the other two steps, you can always toggle between these widths and behaviors by simply swapping the ID value. It’s really that simple.
Example: 100% fluid layout
Step 2: Choose a Template Preset
This is perhaps the most frequently omitted step (they’re all optional), but I use it nearly every time. In a source-order-independent way (good for accessibility and SEO), “Template Presets” provide commonly used template widths compatible with ad-unit dimension standards defined by the Interactive Advertising Bureau, an industry association.
Choose between the six Template Presets (.yui-t1 through .yui-t6) by setting the class value on the document-wrapping div established in Step 1. Most frequently I use yui-t3, which puts the narrow secondary block on the left and makes it 300px wide.
<body>
<div id="doc3" class="yui-t3"></div>
</body>
The Template Presets control two “blocks” of content, which are defined by two divs, each with yui-b (“b” for “block”) class values. Template Presets describe the width and orientation of the secondary block; the main block will take up the rest of the space.
<body>
<div id="doc3" class="yui-t3">
<div class="yui-b"></div>
<div class="yui-b"></div>
</div>
</body>
Use a wrapping div with an ID of yui-main to structurally indicate which block is the main block. This wrapper—not the source order—identifies the main block.
<body>
<div id="doc3" class="yui-t3">
<div id="yui-main">
<div class="yui-b"></div>
</div>
<div class="yui-b"></div>
</div>
</body>
Example: Main and secondary blocks sized and oriented with .yui-t3 Template Preset
Again, regardless of what values you choose in the other steps, you can always toggle between these Template Presets by toggling the class value of your document-wrapping div. It’s really that simple.
Step 3: Nest and Stack Grid Structures.
The bulk of the power of the system is in this third step. The key is that columns are built by parents telling children how to behave. By default, two children each consume half of their parent’s area. Put two units inside a grid structure, and they will sit side-by-side, and they will each take up half the space. Nest this structure and two columns become four. Stack them for rows of columns.
An Even Number of Columns
The default behavior creates two evenly-distributed columns. It’s easy. Define one parent grid with .yui-g (“g” for grid) and two child units with .yui-u (“u” for unit). The code looks like this:
<div class="yui-g">
<div class="yui-u first"></div>
<div class="yui-u"></div>
</div>
Be sure to indicate the “first“ unit because the :first-child pseudo-class selector isn’t supported across all A-grade browsers. It’s unfortunate we need to add this, but luckily it’s not out of place in the markup layer since it is structural information.
Example: Two evenly-distributed columns in the main content block
An Odd Number of Columns
The default system does not work for an odd number of columns without using the included “Special Grids” classes. To create three evenly distributed columns, use the “yui-gb“ Special Grid:
<div class="yui-gb">
<div class="yui-u first"></div>
<div class="yui-u"></div>
<div class="yui-u"></div>
</div>
Example: Three evenly distributed columns in the main content block
Uneven Column Distribution
Special Grids are also used for unevenly distributed column widths. For example, .yui-ge tells the first unit (column) to take up 75% of the parent’s space and the other unit to take just 25%.
<div class="yui-ge">
<div class="yui-u first"></div>
<div class="yui-u"></div>
</div>
Example: Two columns in the main content block split 75%-25%
Putting It All Together
Start with a full-width fluid page (div#doc3). Make the secondary block 180px wide on the right (div.yui-t4). Create three rows of columns: Three evenly distributed columns in the first row (div.yui-gb), two uneven columns (66%-33%) in the second row (div.yui-gc), and two evenly distributed columns in the thrid row.
<body>
<!-- choose fluid page and Template Preset -->
<div id="doc3" class="yui-t4">
<!-- main content block -->
<div id="yui-main">
<div class="yui-b">
<!-- stacked grid structure, Special Grid "b" -->
<div class="yui-gb">
<div class="yui-u first"></div>
<div class="yui-u"></div>
<div class="yui-u"></div>
</div>
<!-- stacked grid structure, Special Grid "c" -->
<div class="yui-gc">
<div class="yui-u first"></div>
<div class="yui-u"></div>
</div>
<!-- stacked grid structure -->
<div class="yui-g">
<div class="yui-u first"></div>
<div class="yui-u"></div>
</div>
</div>
</div>
<!-- secondary content block -->
<div class="yui-b"></div>
</div>
</body>
Example: A complex layout.
Wasn’t that easy? Now that you know the three “levers” of YUI Grids CSS, you’ll be creating headache-free fluid layouts faster than you can say “Peace on Earth”. |
2006 |
Nate Koechley |
natekoechley |
2006-12-20T00:00:00+00:00 |
https://24ways.org/2006/intricate-fluid-layouts/ |
code |
| 244 |
It’s Beginning to Look a Lot Like XSSmas |
I dread the office Secret Santa. I have a knack for choosing well-meaning but inappropriate presents, like a bottle of port for a teetotaller, a cheese-tasting experience for a vegan, or heaven forbid, Spurs socks for an Arsenal supporter. Ok, the last one was intentional.
It’s the same with gifting code. Once, I made a pattern library for A List Apart which I open sourced, and a few weeks later, a glaring security vulnerability was found in it. My gift was so generous that it enabled unrestricted access to any file on any public-facing server that hosted it.
With platforms like GitHub and npm, giving the gift of code is so easy it’s practically a no-brainer. This giant, open source yankee swap helps us do our jobs without starting from scratch with every project. But like any gift-giving, it’s also risky.
Vulnerabilities and Open Source
Open source code is not inherently more or less vulnerable than closed-source code. What makes it higher risk is that the same piece of code gets reused in lots of places, meaning a hacker can use the same exploit mechanism on the same vulnerable code in different apps.
Graph showing the number of open source vulnerabilities published per year, from the State of Open Source Security 2017
In the first 24 ways article this year, Katie referenced a few different types of vulnerability:
Cross-site Request Forgery (also known as CSRF)
SQL Injection
Cross-site Scripting (also known as XSS)
There are many more types of vulnerability, and those that live under the same category share similarities.
For example, my favourite – is it weird to have a favourite vulnerability? – is Cross Site Scripting (XSS), which allows for the injection of scripts into web pages. This is a really common vulnerability often unwittingly added by developers. OWASP (the Open Web Application Security Project) wrote a great article about how to prevent opening the door to XSS attacks – share it generously with your colleagues.
Most vulnerabilities like this are not added intentionally – they’re doors left ajar due to the way something has been scripted, like the over-generous code in my pattern library.
Others, though, are added intentionally. A few months ago, a hacker, disguised as a helpful elf, offered to take over the maintenance of a popular npm package that had been unmaintained for a couple of years. The owner had moved onto other projects, and was keen to see it continue to be maintained by someone else, so transferred ownership. Fast-forward 3 months, it was discovered that the individual had quietly added a malicious package to the codebase, and the obfuscated code in it had been unwittingly installed onto thousands of apps. The code added was designed to harvest Bitcoin if it was run alongside another application. It was only spotted due to a developer’s curiosity.
Another tactic to get developers to unwittingly install malicious packages into their codebase is “typosquatting” – back in August last year, npm reported that a user had been publishing packages with very similar names to popular packages (for example, crossenv instead of cross-env).
This is a big wakeup call for open source maintainers. Techniques like this are likely to be used more as the maintenance of open source libraries becomes an increasing burden to their owners. After all, starting a new project often has a greater reward than maintaining an existing one, but remember, an open source library is for life, not just for Christmas.
Santa’s on his sleigh
If you use open source libraries, chances are that these libraries also use open source libraries. Your app may only have a handful of dependencies, but tucked in the back of that sleigh may be a whole extra sack of dependencies known as deep dependencies (ones that you didn’t directly install, but are dependencies of that dependency), and these can contain vulnerabilities too.
Let’s look at the npm package santa as an example. santa has 8 direct dependencies listed on npm. That seems pretty manageable. But that’s just the tip of the iceberg – have a look at the full dependency tree which contains 109 dependencies – more dependencies than there are Christmas puns in this article. Only one of these direct dependencies has a vulnerability (at the time of writing), but there are actually 13 other known vulnerabilities in santa, which have been introduced through its deeper dependencies.
Fixing vulnerabilities – the ultimate christmas gift
If you’re a maintainer of open source libraries, taking good care of them is the ultimate gift you can give. Keep your dependencies up to date, use a security tool to monitor and alert you when new vulnerabilities are found in your code, and fix or patch them promptly. This will help keep the whole open source ecosystem healthy.
When you find out about a new vulnerability, you have some options:
Fix the vulnerability via an upgrade
You can often fix a vulnerability by upgrading the library to the latest version. Make sure you’re using software that monitors your dependencies for new security issues and lets you know when a fix is ready, otherwise you may be unwittingly using a vulnerable version.
Patch the vulnerable code
Sometimes, a fix for a vulnerable library isn’t possible. This is often the case when a library is no longer being maintained, or the version of the library being used might be so out of date that upgrading it would cause a breaking change. Patches are bits of code that will fix that particular issue, but won’t change anything else.
Switch to a different library
If the library you’re using has no fix or patch, you may be better of switching it out for another one, particularly if it looks like it’s being unmaintained.
Responsibly disclosing vulnerabilities
Knowing how to responsibly disclose vulnerabilities is something I’m ashamed to admit that I didn’t know about before I joined a security company. But it’s so important! On discovering a new vulnerability, a developer has a few options:
A malicious developer will exploit that vulnerability for their own gain.
A reckless (or inexperienced) developer will disclose that vulnerability to the world without following a responsible disclosure process. This opens the door to an unethical developer exploiting the vulnerability. At Snyk, we monitor social media for mentions of newly found vulnerabilities so we can add them to our database and share fixes before they get exploited.
An ethical and aware developer will follow what’s known as a “responsible disclosure process”. They will contact the maintainer of the code privately, allowing reasonable time for them to release a fix for the issue and to give others who use that vulnerable code a chance to fix it too.
It’s important to understand this process if you’re a maintainer or contributor of code. It can be daunting when a report comes in, but understanding and following the right steps will help reduce the risk to the people who use that code.
So what does responsible disclosure look like? I’ll take Node.js’s security disclosure policy as an example. They ask that all security issues that are found in Node.js are reported there. (There’s a separate process for bug found in third-party npm packages). Once you’ve reported a vulnerability, they promise to acknowledge it within 24 hours, and to give a more detailed response within 48 hours. If they find that the issue is indeed a security bug, they’ll give you regular updates about the progress they’re making towards fixing it. As part of this, they’ll figure out which versions are affected, and prepare fixes for them. They’ll assign the vulnerability a CVE (Common Vulnerabilities and Exposures) ID and decide on an embargo date for public disclosure. On the date of the embargo, they announce the vulnerability in their Node.js security mailing list and deploy fixes to nodejs.org.
Tim Kadlec published an in-depth article about responsible disclosures if you’re interested in knowing more. It has some interesting horror stories of what happened when the disclosure process was not followed.
Encourage responsible disclosure
Add a SECURITY.md file to your project so someone who wants to message you about a vulnerability can do so without having to hunt around for contact details. Last year, Snyk published a State of Open Source Security report that found 79.5% of maintainers do not have a public disclosure policy. Those that did were considerably more likely to get notified privately about a vulnerability – 73% of maintainers who had one had been notified, vs 21% of maintainers who hadn’t published one one.
Stats from the State of Open Source Security 2017
Bug bounties
Some companies run bug bounties to encourage the responsible disclosure of vulnerabilities. By offering a reward for finding and safely disclosing a vulnerability, it also reduces the enticement of exploiting a vulnerability over reporting it and getting a quick cash reward. Hackerone is a community of ethical hackers who pentest apps that have signed up for the scheme and get paid when they find a new vulnerability. Wordpress is one such participant, and you can see the long list of vulnerabilities that have been disclosed as part of that program.
If you don’t have such a bounty, be prepared to get the odd vulnerability extortion email. Scott Helme, who founded securityheaders.com and report-uri.com, wrote a post about some of the requests he gets for a report about a critical vulnerability in exchange for money.
On one hand, I want to be as responsible as possible and if my users are at risk then I need to know and patch this issue to protect them. On the other hand this is such irresponsible and unethical behaviour that interacting with this person seems out of the question.
A gift worth giving
It’s time to brush the dust off those old gifts that we shared and forgot about. Practice good hygiene and run them through your favourite security tool – I’m just a little biased towards Snyk, but as Katie mentioned, there’s also npm audit if you use Node.js, and most source code managers like GitHub and GitLab have basic vulnerability alert capabilities.
Stats from the State of Open Source Security 2017
Most importantly, patch or upgrade away those vulnerabilities away, and if you want to share that Christmas spirit, open fixes for your favourite open source projects, too. |
2018 |
Anna Debenham |
annadebenham |
2018-12-17T00:00:00+00:00 |
https://24ways.org/2018/its-beginning-to-look-a-lot-like-xssmas/ |
code |
| 241 |
Jank-Free Image Loads |
There are a few fundamental problems with embedding images in pages of hypertext; perhaps chief among them is this: text is very light and loads rather fast; images are much heavier and arrive much later. Consequently, millions (billions?) of times a day, a hapless Web surfer will start reading some text on a page, and then —
Your browser doesn’t support HTML5 video. Here is
a link to the video instead.
— oops! — an image pops in above it, pushing said text down the page, and our poor reader loses their place.
By default, partially-loaded pages have the user experience of a slippery fish, or spilled jar of jumping beans. For the rest of this article, I shall call that jarring, no-good jumpiness by its name: jank. And I’ll chart a path into a jank-free future – one in which it’s easy and natural to author <img> elements that load like this:
Your browser doesn’t support HTML5 video. Here is
a link to the video instead.
Jank is a very old problem, and there is a very old solution to it: the width and height attributes on <img>. The idea is: if we stick an image’s dimensions right into the HTML, browsers can know those dimensions before the image loads, and reserve some space on the layout for it so that nothing gets bumped down the page when the image finally arrives.
width
Specifies the intended width of the image in pixels. When given together with the height, this allows user agents to reserve screen space for the image before the image data has arrived over the network.
—The HTML 3.2 Specification, published on January 14 1997
Unfortunately for us, when width and height were first spec’d and implemented, layouts were largely fixed and images were usually only intended to render at their fixed, actual dimensions. When image sizing gets fluid, width and height get weird:
See the Pen fluid width + fixed height = distortion by Eric Portis (@eeeps) on CodePen.
width and height are too rigid for the responsive world. What we need, and have needed for a very long time, is a way to specify fixed aspect ratios, to pair with our fluid widths.
I have good news, bad news, and great news.
The good news is, there are ways to do this, now, that work in every browser. Responsible sites, and responsible developers, go through the effort to do them.
The bad news is that these techniques are all terrible, cumbersome hacks. They’re difficult to remember, difficult to understand, and they can interact with other pieces of CSS in unexpected ways.
So, the great news: there are two on-the-horizon web platform features that are trying to make no-jank, fixed-aspect-ratio, fluid-width images a natural part of the web platform.
aspect-ratio in CSS
The first proposed feature? An aspect-ratio property in CSS!
This would allow us to write CSS like this:
img {
width: 100%;
}
.thumb {
aspect-ratio: 1/1;
}
.hero {
aspect-ratio: 16/9;
}
This’ll work wonders when we need to set aspect ratios for whole classes of images, which are all sized to fit within pre-defined layout slots, like the .thumb and .hero images, above.
Alas, the harder problem, in my experience, is not images with known-ahead-of-time aspect ratios. It’s images – possibly user generated images – that can have any aspect ratio. The really tricky problem is unknown-when-you’re-writing-your-CSS aspect ratios that can vary per-image. Using aspect-ratio to reserve space for images like this requires inline styles:
<img src="image.jpg" style="aspect-ratio: 5/4" />
And inline styles give me the heebie-jeebies! As a web developer of a certain age, I have a tiny man in a blue beanie permanently embedded deep within my hindbrain, who cries out in agony whenever I author a style="" attribute. And you know what? The old man has a point! By sticking super-high-specificity inline styles in my content, I’m cutting off my, (or anyone else’s) ability to change those aspect ratios, for whatever reason, later.
How might we specify aspect ratios at a lower level? How might we give browsers information about an image’s dimensions, without giving them explicit instructions about how to style it?
I’ll tell you: we could give browsers the intrinsic aspect ratio of the image in our HTML, rather than specifying an extrinsic aspect ratio!
A brief note on intrinsic and extrinsic sizing
What do I mean by “intrinsic” and “extrinsic?”
The intrinsic size of an image is, put simply, how big it’d be if you plopped it onto a page and applied no CSS to it whatsoever. An 800×600 image has an intrinsic width of 800px.
The extrinsic size of an image, then, is how large it ends up after CSS has been applied. Stick a width: 300px rule on that same 800×600 image, and its intrinsic size (accessible via the Image.naturalWidth property, in JavaScript) doesn’t change: its intrinsic size is still 800px. But this image now has an extrinsic size (accessible via Image.clientWidth) of 300px.
It surprised me to learn this year that height and width are interpreted as presentational hints and that they end up setting extrinsic dimensions (albeit ones that, unlike inline styles, have absolutely no specificity).
CSS aspect-ratio lets us avoid setting extrinsic heights and widths – and instead lets us give images (or anything else) an extrinsic aspect ratio, so that as soon as we set one dimension (possibly to a fluid width, like 100%!), the other dimension is set automatically in relation to it.
The last tool I’m going to talk about gets us out of the extrinsic sizing game all together — which, I think, is only appropriate for a feature that we’re going to be using in HTML.
intrinsicsize in HTML
The proposed intrinsicsize attribute will let you do this:
<img src="image.jpg" intrinsicsize="800x600" />
That tells the browser, “hey, this image.jpg that I’m using here – I know you haven’t loaded it yet but I’m just going to let you know right away that it’s going to have an intrinsic size of 800×600.” This gives the browser enough information to reserve space on the layout for the image, and ensures that any and all extrinsic sizing instructions, specified in our CSS, will layer cleanly on top of this, the image’s intrinsic size.
You may ask (I did!): wait, what if my <img> references multiple resources, which all have different intrinsic sizes? Well, if you’re using srcset, intrinsicsize is a bit of a misnomer – what the attribute will do then, is specify an intrinsic aspect ratio:
<img
srcset="300x200.jpg 300w,
600x400.jpg 600w,
900x600.jpg 900w,
1200x800.jpg 1200w"
sizes="75vw"
intrinsicsize="3x2" />
In the future (and behind the “Experimental Web Platform Features” flag right now, in Chrome 71+), asking this image for its .naturalWidth would not return 3 – it will return whatever 75vw is, given the current viewport width. And Image.naturalHeight will return that width, divided by the intrinsic aspect ratio: 3/2.
Can’t wait
I seem to have gotten myself into the weeds a bit. Sizing on the web is complicated!
Don’t let all of these details bury the big takeaway here: sometime soon (🤞 2019‽ 🤞), we’ll be able to toss our terrible aspect-ratio hacks into the dustbin of history, get in the habit of setting aspect-ratios in CSS and/or intrinsicsizes in HTML, and surf a less-frustrating, more-performant, less-janky web. I can’t wait! |
2018 |
Eric Portis |
ericportis |
2018-12-21T00:00:00+00:00 |
https://24ways.org/2018/jank-free-image-loads/ |
code |
| 153 |
JavaScript Internationalisation |
or: Why Rudolph Is More Than Just a Shiny Nose
Dunder sat, glumly staring at the computer screen.
“What’s up, Dunder?” asked Rudolph, entering the stable and shaking off the snow from his antlers.
“Well,” Dunder replied, “I’ve just finished coding the new reindeer intranet Santa Claus asked me to do. You know how he likes to appear to be at the cutting edge, talking incessantly about Web 2.0, AJAX, rounded corners; he even spooked Comet recently by talking about him as if he were some pushy web server.
“I’ve managed to keep him happy, whilst also keeping it usable, accessible, and gleaming — and I’m still on the back row of the sleigh! But anyway, given the elves will be the ones using the site, and they come from all over the world, the site is in multiple languages. Which is great, except when it comes to the preview JavaScript I’ve written for the reindeer order form. Here, have a look…”
As he said that, he brought up the textileRef:8234272265470b85d91702:linkStartMarker:“order
form in French”:/examples/javascript-internationalisation/initial.fr.html on the screen. (Same in English).
“Looks good,” said Rudolph.
“But if I add some items,” said Dunder, “the preview appears in English, as it’s hard-coded in the JavaScript. I don’t want separate code for each language, as that’s just silly — I thought about just having if statements, but that doesn’t scale at all…”
“And there’s more, you aren’t displaying large numbers in French properly, either,” added Rudolph, who had been playing and looking at part of the source code:
function update_text() {
var hay = getValue('hay');
var carrots = getValue('carrots');
var bells = getValue('bells');
var total = 50 * bells + 30 * hay + 10 * carrots;
var out = 'You are ordering '
+ pretty_num(hay) + ' bushel' + pluralise(hay) + ' of hay, '
+ pretty_num(carrots) + ' carrot' + pluralise(carrots)
+ ', and ' + pretty_num(bells) + ' shiny bell' + pluralise(bells)
+ ', at a total cost of <strong>' + pretty_num(total)
+ '</strong> gold pieces. Thank you.';
document.getElementById('preview').innerHTML = out;
}
function pretty_num(n) {
n += '';
var o = '';
for (i=n.length; i>3; i-=3) {
o = ',' + n.slice(i-3, i) + o;
}
o = n.slice(0, i) + o;
return o;
}
function pluralise(n) {
if (n!=1) return 's';
return '';
}
“Oh, botheration!” cried Dunder. “This is just so complicated.”
“It doesn’t have to be,” said Rudolph, “you just have to think about things in a slightly different way from what you’re used to. As we’re only a simple example, we won’t be able to cover all possibilities, but for starters, we need some way of providing different information to the script dependent on the language. We’ll create a global i18n object, say, and fill it with the correct language information. The first variable we’ll need will be a thousands separator, and then we can change the pretty_num function to use that instead:
function pretty_num(n) {
n += '';
var o = '';
for (i=n.length; i>3; i-=3) {
o = i18n.thousands_sep + n.slice(i-3, i) + o;
}
o = n.slice(0, i) + o;
return o;
}
“The i18n object will also contain our translations, which we will access through a function called _() — that’s just an underscore. Other languages have a function of the same name doing the same thing. It’s very simple:
function _(s) {
if (typeof(i18n)!='undefined' && i18n[s]) {
return i18n[s];
}
return s;
}
“So if a translation is available and provided, we’ll use that; otherwise we’ll default to the string provided — which is helpful if the translation begins to lag behind the site’s text at all, as at least something will be output.”
“Got it,” said Dunder. “ _('Hello Dunder') will print the translation of that string, if one exists, ‘Hello Dunder’ if not.”
“Exactly. Moving on, your plural function breaks even in English if we have a word where the plural doesn’t add an s — like ‘children’.”
“You’re right,” said Dunder. “How did I miss that?”
“No harm done. Better to provide both singular and plural words to the function and let it decide which to use, performing any translation as well:
function pluralise(s, p, n) {
if (n != 1) return _(p);
return _(s);
}
“We’d have to provide different functions for different languages as we employed more elves and got more complicated — for example, in Polish, the word ‘file’ pluralises like this: 1 plik, 2-4 pliki, 5-21 plików, 22-24 pliki, 25-31 plików, and so on.” (More information on plural forms)
“Gosh!”
“Next, as different languages have different word orders, we must stop using concatenation to construct sentences, as it would be impossible for other languages to fit in; we have to keep coherent strings together. Let’s rewrite your update function, and then go through it:
function update_text() {
var hay = getValue('hay');
var carrots = getValue('carrots');
var bells = getValue('bells');
var total = 50 * bells + 30 * hay + 10 * carrots;
hay = sprintf(pluralise('%s bushel of hay', '%s bushels of hay', hay), pretty_num(hay));
carrots = sprintf(pluralise('%s carrot', '%s carrots', carrots), pretty_num(carrots));
bells = sprintf(pluralise('%s shiny bell', '%s shiny bells', bells), pretty_num(bells));
var list = sprintf(_('%s, %s, and %s'), hay, carrots, bells);
var out = sprintf(_('You are ordering %s, at a total cost of <strong>%s</strong> gold pieces.'),
list, pretty_num(total));
out += ' ';
out += _('Thank you.');
document.getElementById('preview').innerHTML = out;
}
“ sprintf is a function in many other languages that, given a format string and some variables, slots the variables into place within the string. JavaScript doesn’t have such a function, so we’ll write our own. Again, keep it simple for now, only integers and strings; I’m sure more complete ones can be found on the internet.
function sprintf(s) {
var bits = s.split('%');
var out = bits[0];
var re = /^([ds])(.*)$/;
for (var i=1; i<bits.length; i++) {
p = re.exec(bits[i]);
if (!p || arguments[i]==null) continue;
if (p[1] == 'd') {
out += parseInt(arguments[i], 10);
} else if (p[1] == 's') {
out += arguments[i];
}
out += p[2];
}
return out;
}
“Lastly, we need to create one file for each language, containing our i18n object, and then include that from the relevant HTML. Here’s what a blank translation file would look like for your order form:
var i18n = {
thousands_sep: ',',
"%s bushel of hay": '',
"%s bushels of hay": '',
"%s carrot": '',
"%s carrots": '',
"%s shiny bell": '',
"%s shiny bells": '',
"%s, %s, and %s": '',
"You are ordering %s, at a total cost of <strong>%s</strong> gold pieces.": '',
"Thank you.": ''
};
“If you implement this across the intranet, you’ll want to investigate the xgettext program, which can automatically extract all strings that need translating from all sorts of code files into a standard .po file (I think Python mode works best for JavaScript). You can then use a different program to take the translated .po file and automatically create the language-specific JavaScript files for us.” (e.g. German .po file for PledgeBank, mySociety’s .po-.js script, example output)
With a flourish, Rudolph finished editing. “And there we go, localised JavaScript in English, French, or German, all using the same main code.”
“Thanks so much, Rudolph!” said Dunder.
“I’m not just a pretty nose!” Rudolph quipped. “Oh, and one last thing — please comment liberally explaining the context of strings you use. Your translator will thank you, probably at the same time as they point out the four hundred places you’ve done something in code that only works in your language and no-one else’s…”
Thanks to Tim Morley and Edmund Grimley Evans for the French and German translations respectively. |
2007 |
Matthew Somerville |
matthewsomerville |
2007-12-08T00:00:00+00:00 |
https://24ways.org/2007/javascript-internationalisation/ |
code |
| 37 |
JavaScript Modules the ES6 Way |
JavaScript admittedly has plenty of flaws, but one of the largest and most prominent is the lack of a module system: a way to split up your application into a series of smaller files that can depend on each other to function correctly.
This is something nearly all other languages come with out of the box, whether it be Ruby’s require, Python’s import, or any other language you’re familiar with. Even CSS has @import! JavaScript has nothing of that sort, and this has caused problems for application developers as they go from working with small websites to full client-side applications. Let’s be clear: it doesn’t mean the new module system in the upcoming version of JavaScript won’t be useful to you if you’re building smaller websites rather than the next Instagram.
Thankfully, the lack of a module system will soon be a problem of the past. The next version of JavaScript, ECMAScript 6, will bring with it a full-featured module and dependency management solution for JavaScript. The bad news is that it won’t be landing in browsers for a while yet – but the good news is that the specification for the module system and how it will look has been finalised. The even better news is that there are tools available to get it all working in browsers today without too much hassle. In this post I’d like to give you the gift of JS modules and show you the syntax, and how to use them in browsers today. It’s much simpler than you might think.
What is ES6?
ECMAScript is a scripting language that is standardised by a company called Ecma International. JavaScript is an implementation of ECMAScript. ECMAScript 6 is simply the next version of the ECMAScript standard and, hence, the next version of JavaScript. The spec aims to be fully comfirmed and complete by the end of 2014, with a target initial release date of June 2015. It’s impossible to know when we will have full feature support across the most popular browsers, but already some ES6 features are landing in the latest builds of Chrome and Firefox. You shouldn’t expect to be able to use the new features across browsers without some form of additional tooling or library for a while yet.
The ES6 module spec
The ES6 module spec was fully confirmed in July 2014, so all the syntax I will show you in this article is not expected to change. I’ll first show you the syntax and the new APIs being added to the language, and then look at how to use them today. There are two parts to the new module system. The first is the syntax for declaring modules and dependencies in your JS files, and the second is a programmatic API for loading in modules manually. The first is what most people are expected to use most of the time, so it’s what I’ll focus on more.
Module syntax
The key thing to understand here is that modules have two key components. First, they have dependencies. These are things that the module you are writing depends on to function correctly. For example, if you were building a carousel module that used jQuery, you would say that jQuery is a dependency of your carousel. You import these dependencies into your module, and we’ll see how to do that in a minute. Second, modules have exports. These are the functions or variables that your module exposes publicly to anything that imports it. Using jQuery as the example again, you could say that jQuery exports the $ function. Modules that depend on and hence import jQuery get access to the $ function, because jQuery exports it.
Another important thing to note is that when I discuss a module, all I really mean is a JavaScript file. There’s no extra syntax to use other than the new ES6 syntax. Once ES6 lands, modules and files will be analogous.
Named exports
Modules can export multiple objects, which can be either plain old variables or JavaScript functions. You denote something to be exported with the export keyword:
export function double(x) {
return x + x;
};
You can also store something in a variable then export it. If you do that, you have to wrap the variable in a set of curly braces.
var double = function(x) {
return x + x;
}
export { double };
A module can then import the double function like so:
import { double } from 'mymodule';
double(2); // 4
Again, curly braces are required around the variable you would like to import. It’s also important to note that from 'mymodule' will look for a file called mymodule.js in the same directory as the file you are requesting the import from. There is no need to add the .js extension.
The reason for those extra braces is that this syntax lets you export multiple variables:
var double = function(x) {
return x + x;
}
var square = function(x) {
return x * x;
}
export { double, square }
I personally prefer this syntax over the export function …, but only because it makes it much clearer to me what the module exports. Typically I will have my export {…} line at the bottom of the file, which means I can quickly look in one place to determine what the module is exporting.
A file importing both double and square can do so in just the way you’d expect:
import { double, square } from 'mymodule';
double(2); // 4
square(3); // 9
With this approach you can’t easily import an entire module and all its methods. This is by design – it’s much better and you’re encouraged to import just the functions you need to use.
Default exports
Along with named exports, the system also lets a module have a default export. This is useful when you are working with a large library such as jQuery, Underscore, Backbone and others, and just want to import the entire library. A module can define its default export (it can only ever have one default export) like so:
export default function(x) {
return x + x;
}
And that can be imported:
import double from 'mymodule';
double(2); // 4
This time you do not use the curly braces around the name of the object you are importing. Also notice how you can name the import whatever you’d like. Default exports are not named, so you can import them as anything you like:
import christmas from 'mymodule';
christmas(2); // 4
The above is entirely valid.
Although it’s not something that is used too often, a module can have both named exports and a default export, if you wish.
One of the design goals of the ES6 modules spec was to favour default exports. There are many reasons behind this, and there is a very detailed discussion on the ES Discuss site about it. That said, if you find yourself preferring named exports, that’s fine, and you shouldn’t change that to meet the preferences of those designing the spec.
Programmatic API
Along with the syntax above, there is also a new API being added to the language so you can programmatically import modules. It’s pretty rare you would use this, but one obvious example is loading a module conditionally based on some variable or property. You could easily import a polyfill, for example, if the user’s browser didn’t support a feature your app relied on. An example of doing this is:
if(someFeatureNotSupported) {
System.import('my-polyfill').then(function(myPolyFill) {
// use the module from here
});
}
System.import will return a promise, which, if you’re not familiar, you can read about in this excellent article on HTMl5 Rocks by Jake Archibald. A promise basically lets you attach callback functions that are run when the asynchronous operation (in this case, System.import), is complete.
This programmatic API opens up a lot of possibilities and will also provide hooks to allow you to register callbacks that will run at certain points in the lifetime of a module. Those hooks and that syntax are slightly less set in stone, but when they are confirmed they will provide really useful functionality. For example, you could write code that would run every module that you import through something like JSHint before importing it. In development that would provide you with an easy way to keep your code quality high without having to run a command line watch task.
How to use it today
It’s all well and good having this new syntax, but right now it won’t work in any browser – and it’s not likely to for a long time. Maybe in next year’s 24 ways there will be an article on how you can use ES6 modules with no extra work in the browser, but for now we’re stuck with a bit of extra work.
ES6 module transpiler
One solution is to use the ES6 module transpiler, a compiler that lets you write your JavaScript using the ES6 module syntax (actually a subset of it – not quite everything is supported, but the main features are) and have it compiled into either CommonJS-style code (CommonJS is the module specification that NodeJS and Browserify use), or into AMD-style code (the spec RequireJS uses). There are also plugins for all the popular build tools, including Grunt and Gulp.
The advantage of using this transpiler is that if you are already using a tool like RequireJS or Browserify, you can drop the transpiler in, start writing in ES6 and not worry about any additional work to make the code work in the browser, because you should already have that set up already. If you don’t have any system in place for handling modules in the browser, using the transpiler doesn’t really make sense. Remember, all this does is convert ES6 module code into CommonJS- or AMD-compliant JavaScript. It doesn’t do anything to help you get that code running in the browser, but if you have that part sorted it’s a really nice addition to your workflow. If you would like a tutorial on how to do this, I wrote a post back in June 2014 on using ES6 with the ES6 module transpiler.
SystemJS
Another solution is SystemJS. It’s the best solution in my opinion, particularly if you are starting a new project from scratch, or want to use ES6 modules on a project where you have no current module system in place. SystemJS is a spec-compliant universal module loader: it loads ES6 modules, AMD modules, CommonJS modules, as well as modules that just add a variable to the global scope (window, in the browser).
To load in ES6 files, SystemJS also depends on two other libraries: the ES6 module loader polyfill; and Traceur. Traceur is best accessed through the bower-traceur package, as the main repository doesn’t have an easy to find downloadable version. The ES6 module load polyfill implements System.import, and lets you load in files using it. Traceur is an ES6-to-ES5 module loader. It takes code written in ES6, the newest version of JavaScript, and transpiles it into ES5, the version of JavaScript widely implemented in browsers. The advantage of this is that you can play with the new features of the language today, even though they are not supported in browsers. The drawback is that you have to run all your files through Traceur every time you save them, but this is easily automated. Additionally, if you use SystemJS, the Traceur compilation is done automatically for you.
All you need to do to get SystemJS running is to add a <script> element to load SystemJS into your webpage. It will then automatically load the ES6 module loader and Traceur files when it needs them. In your HTML you then need to use System.import to load in your module:
<script>
System.import('./app');
</script>
When you load the page, app.js will be asynchronously loaded. Within app.js, you can now use ES6 modules. SystemJS will detect that the file is an ES6 file, automatically load Traceur, and compile the file into ES5 so that it works in the browser. It does all this dynamically in the browser, but there are tools to bundle your application in production, so it doesn’t make a lot of requests on the live site. In development though, it makes for a really nice workflow.
When working with SystemJS and modules in general, the best approach is to have a main module (in our case app.js) that is the main entry point for your application. app.js should then be responsible for loading all your application’s modules. This forces you to keep your application organised by only loading one file initially, and having the rest dealt with by that file.
SystemJS also provides a workflow for bundling your application together into one file.
Conclusion
ES6 modules may be at least six months to a year away (if not more) but that doesn’t mean they can’t be used today. Although there is an overhead to using them now – with the work required to set up SystemJS, the module transpiler, or another solution – that doesn’t mean it’s not worthwhile. Using any module system in the browser, whether that be RequireJS, Browserify or another alternative, requires extra tooling and libraries to support it, and I would argue that the effort to set up SystemJS is no greater than that required to configure any other tool. It also comes with the extra benefit that when the syntax is supported in browsers, you get a free upgrade. You’ll be able to remove SystemJS and have everything continue to work, backed by the native browser solution.
If you are starting a new project, I would strongly advocate using ES6 modules. It is a syntax and specification that is not going away at all, and will soon be supported in browsers. Investing time in learning it now will pay off hugely further down the road.
Further reading
If you’d like to delve further into ES6 modules (or ES6 generally) and using them today, I recommend the following resources:
ECMAScript 6 modules: the final syntax by Axel Rauschmayer
Practical Workflows for ES6 Modules by Guy Bedford
ECMAScript 6 resources for the curious JavaScripter by Addy Osmani
Tracking ES6 support by Addy Osmani
ES6 Tools List by Addy Osmani
Using Grunt and the ES6 Module Transpiler by Thomas Boyt
JavaScript Modules and Dependencies with jspm by myself
Using ES6 Modules Today by Guy Bedford |
2014 |
Jack Franklin |
jackfranklin |
2014-12-03T00:00:00+00:00 |
https://24ways.org/2014/javascript-modules-the-es6-way/ |
code |
| 201 |
Lint the Web Forward With Sonarwhal |
Years ago, when I was in a senior in college, much of my web development courses focused on two things: the basics like HTML and CSS (and boy, do I mean basic), and Adobe Flash. I spent many nights writing ActionScript 3.0 to build interactions for the websites that I would add to my portfolio. A few months after graduating, I built one website in Flash for a client, then never again. Flash was dying, and it became obsolete in my résumé and portfolio.
That was my first lesson in the speed at which things change in technology, and what a daunting realization that was as a new graduate looking to enter the professional world. Now, seven years later, I work on the Microsoft Edge team where I help design and build a tool that would have lessened my early career anxieties: sonarwhal.
Sonarwhal is a linting tool, built by and for the web community. The code is open source and lives under the JS Foundation. It helps web developers and designers like me keep up with the constant change in technology while simultaneously teaching how to code better websites.
Introducing sonarwhal’s mascot Nellie
Good web development is hard. It is more than HTML, CSS, and JavaScript: developers are expected to have a grasp of accessibility, performance, security, emerging standards, and more, all while refreshing this knowledge every few months as the web evolves. It’s a lot to keep track of.
Web development is hard
Staying up-to-date on all this knowledge is one of the driving forces for developing this scanning tool. Whether you are just starting out, are a student, or you have over a decade of experience, the sonarwhal team wants to help you build better websites for all browsers.
Currently sonarwhal checks for best practices in five categories: Accessibility, Interoperability, Performance, PWAs, and Security. Each check is called a “rule”. You can configure them and even create your own rules if you need to follow some specific guidelines for your project (e.g. validate analytics attributes, title format of pages, etc.).
You can use sonarwhal in two ways:
An online version, that provides a quick and easy way to scan any public website.
A command line tool, if you want more control over the configuration, or want to integrate it into your development flow.
The Online Scanner
The online version offers a streamlined way to scan a website; just enter a URL and you will get a web page of scan results with a permalink that you can share and revisit at any time.
The online version of sonarwal
When my team works on a new rule, we spend the bulk of our time carefully researching each subject, finding sources, and documenting it rather than writing the rule’s code. Not only is it important that we get you the right results, but we also want you to understand why something is failing. Next to each failing rule you’ll find a link to its detailed documentation, explaining why you should care about it, what exactly we are testing, examples that pass and examples that don’t, and useful links to even more in-depth documentation if you are interested in the subject.
We hope that between reading the documentation and continued use of sonarwhal, developers can stay on top of best practices. As devs continue to build sites and identify recurring issues that appear in their results, they will hopefully start to automatically include those missing elements or fix those pieces of code that are producing errors. This also isn’t a one-way communication: the documentation is not only available on the sonarwhal site, but also on GitHub for editing so you can help us make it even better!
A results report
The current configuration for the online scanner is very strict, so it might hurt your feelings (it did when I first tested it on my personal website). But you can configure sonarwhal to any level of strictness as well as customize the command line tool to your needs!
Sonarwhal’s CLI
The CLI gives you full control of sonarwhal: what rules to use, tweaks to them, domains that are out of your control, and so on. You will need the latest node LTS (v8) or Stable (v9) and your favorite package manager, such as npm:
npm install -g sonarwhal
You can now run sonarwhal from anywhere via:
sonarwhal https://example.com
Using the CLI
The configuration is done via a .sonarwhalrc file. When analyzing a site, if no file is available, you will be prompted to answer a series of questions:
What connector do you want to use? Connectors are what sonarwhal uses to access a website and gather all the information about the requests, resources, HTML, etc. Currently it supports jsdom, Microsoft Edge, and Google Chrome.
What formatter? This is how you want to see the results: summary, stylish, etc. Make sure to look at the full list. Some are concise for, perfect for a quick build assessment, while others are more verbose and informative.
Do you want to use the recommended rules configuration? Rules are the things we are validating. Unless you’ve read the documentation and know what you are doing, first timers should probably use the recommended configuration.
What browsers are you targeting? One of the best features of sonarwhal is that rules can adapt their feedback depending on your targeted browsers, suggesting to add or remove things. For example, the rule “Highest Document Mode” will tell you to add the “X-UA-Compatible” header if IE10 or lower is targeted or remove if the opposite is true.
sonarwhal configuration generator questions
Once you answer all these questions the scan will start and you will have a .sonarwhalrc file similar to the following:
{
"connector": {
"name": "jsdom",
"options": {
"waitFor": 1000
}
},
"formatters": "stylish",
"rulesTimeout": 120000,
"rules": {
"apple-touch-icons": "error",
"axe": "error",
"content-type": "error",
"disown-opener": "error",
"highest-available-document-mode": "error",
"validate-set-cookie-header": "warning",
// ...
}
}
You should see the scan initiate in the command line and within a few seconds the results should start to appear. Remember, the scan results will look different depending on which formatter you selected so try each one out to see which one you like best.
sonarwhal results on my website and hurting my feelings 💔
Now that you have a list of errors, you can get to work improving the site! Note though, that when you scan your website, it scans all the resources on that page and if you’ve added something like analytics or fonts hosted elsewhere, you are unable to change those files. You can configure the CLI to ignore files from certain domains so that you are only getting results for files you are in control of.
The documentation should give enough guidance on how to fix the errors, but if it’s insufficient, please help us and suggest edits or contribute back to it. This is a community effort and chances are someone else will have the same question as you.
When I scanned both my websites, sonarwhal alerted me to not having an Apple Touch Icon. If I search on the web as opposed to using the sonarwhal documentation, the first top 3 results give me outdated information: I need to include many different icon sizes. I don’t need to include all the different size icons that target different devices. Declaring one icon sized 180px x 180px will provide a large enough icon for devices and it will scale down as appropriate for people on older devices.
The information at the top of the search results isn’t always the correct answer to an issue and we don’t want you to have to search through outdated documentation. As sonarwhal’s capabilities expand, the goal is for it to be the one stop shop for helping preflight your website.
The journey up until now and looking forward
On the Microsoft Edge team, we’re passionate about empowering developers to build great websites. Every day we see so many sites come through our issue tracker. (Thanks for filing those bugs, they help us make Microsoft Edge better and better!) Some issues we see over and over are honest mistakes or outdated ‘best practices’ that could be avoided, so we built this tool to help everyone help make the web a better place.
When we decided to create sonarwhal, we wanted to create a tool that would help developers write better and more up-to-date code for their websites. We want sonarwhal to be useful to anyone so, early on, we defined three guiding principles we’ve used along the way:
Community Driven. We build for the community’s best interests. The web belongs to everyone and this project should too. Not only is it open source, we’ve also donated it to the JS Foundation and have an inclusive governance model that welcomes the collaboration of anyone, individual or company.
User Centric. We want to put the user at the center, making sonarwhal configurable for your needs and easy to use no matter what your skill level is.
Collaborative. We didn’t want to reinvent the wheel, so we collaborated with existing tools and services that help developers build for the web. Some examples are aXe, snyk.io, Cloudinary, etc.
This is just the beginning and we still have lots to do. We’re hard at work on a backlog of exciting features for future releases, such as:
New rules for a variety of areas like performance, accessibility, security, progressive web apps, and more.
A plug-in for Visual Studio Code: we want sonarwhal to help you write better websites, and what better moment than when you are in your editor.
Configuration options for the online service: as we fine tune the infrastructure, the rule configuration for our scanner is locked, but we look forward to adding CLI customization options here in the near future.
This is a tool for the web community by the web community so if you are excited about sonarwhal, making a better web, and want to contribute, we have a few issues where you might be able to help. Also, don’t forget to check the rest of the sonarwhal GitHub organization. PRs are always welcome and appreciated!
Let us know what you think about the scanner at @NarwhalNellie on Twitter and we hope you’ll help us lint the web forward! |
2017 |
Stephanie Drescher |
stephaniedrescher |
2017-12-02T00:00:00+00:00 |
https://24ways.org/2017/lint-the-web-forward-with-sonarwhal/ |
code |
| 20 |
Make Your Browser Dance |
It was a crisp winter’s evening when I pulled up alongside the pier. I stepped out of my car and the bitterly cold sea air hit my face. I walked around to the boot, opened it and heaved out a heavy flight case. I slammed the boot shut, locked the car and started walking towards the venue.
This was it. My first gig. I thought about all those weeks of preparation: editing video clips, creating 3-D objects, making coloured patterns, then importing them all into software and configuring effects to change as the music did; targeting frequency, beat, velocity, modifying size, colour, starting point; creating playlists of these… and working out ways to mix them as the music played.
This was it. This was me VJing.
This was all a lifetime (well a decade!) ago.
When I started web designing, VJing took a back seat. I was more interested in interactive layouts, semantic accessible HTML, learning all the IE bugs and mastering the quirks that CSS has to offer. More recently, I have been excited by background gradients, 3-D transforms, the @keyframe directive, as well as new APIs such as getUserMedia, indexedDB, the Web Audio API
But wait, have I just come full circle? Could it be possible, with these wonderful new things in technologies I am already familiar with, that I could VJ again, right here, in a browser?
Well, there’s only one thing to do: let’s try it!
Let’s take to the dance floor
Over the past couple of years working in The Lab I have learned to take a much more iterative approach to projects than before. One of my new favourite methods of working is to create a proof of concept to make sure my theory is feasible, before going on to create a full-blown product. So let’s take the same approach here.
The main VJing functionality I want to recreate is manipulating visuals in relation to sound. So for my POC I need to create a visual, with parameters that can be changed, then get some sound and see if I can analyse that sound to detect some data, which I can then use to manipulate the visual parameters. Easy, right?
So, let’s start at the beginning: creating a simple visual. For this I’m going to create a CSS animation. It’s just a funky i element with the opacity being changed to make it flash.
See the Pen Creating a light by Rumyra (@Rumyra) on CodePen
A note about prefixes: I’ve left them out of the code examples in this post to make them easier to read. Please be aware that you may need them. I find a great resource to find out if you do is caniuse.com. You can also check out all the code for the examples in this article
Start the music
Well, that’s pretty easy so far. Next up: loading in some sound. For this we’ll use the Web Audio API. The Web Audio API is based around the concept of nodes. You have a source node: the sound you are loading in; a destination node: usually the device’s speakers; and any number of processing nodes in between. All this processing that goes on with the audio is sandboxed within the AudioContext.
So, let’s start by initialising our audio context.
var contextClass = window.AudioContext;
if (contextClass) {
//web audio api available.
var audioContext = new contextClass();
} else {
//web audio api unavailable
//warn user to upgrade/change browser
}
Now let’s load our sound file into the new context we created with an XMLHttpRequest.
function loadSound() {
//set audio file url
var audioFileUrl = '/octave.ogg';
//create new request
var request = new XMLHttpRequest();
request.open("GET", audioFileUrl, true);
request.responseType = "arraybuffer";
request.onload = function() {
//take from http request and decode into buffer
context.decodeAudioData(request.response, function(buffer) {
audioBuffer = buffer;
});
}
request.send();
}
Phew! Now we’ve loaded in some sound! There are plenty of things we can do with the Web Audio API: increase volume; add filters; spatialisation. If you want to dig deeper, the O’Reilly Web Audio API book by Boris Smus is available to read online free.
All we really want to do for this proof of concept, however, is analyse the sound data. To do this we really need to know what data we have.
Learning the steps
Let’s take a minute to step back and remember our school days and science class. I’m sure if I drew a picture of a sound wave, we would all start nodding our heads.
The sound you hear is caused by pressure differences in the particles in the air. Sound pushes these particles together, causing vibrations. Amplitude is basically strength of pressure. A simple example of change of amplitude is when you increase the volume on your stereo and the output wave increases in size.
This is great when everything is analogue, but the waveform varies continuously and it’s not suitable for digital processing: there’s an infinite set of values. For digital processing, we need discrete numbers.
We have to sample the waveform at set time intervals, and record data such as amplitude and frequency. Luckily for us, just the fact we have a digital sound file means all this hard work is done for us. What we’re doing in the code above is piping that data in the audio context. All we need to do now is access it.
We can do this with the Web Audio API’s analysing functionality. Just pop in an analysing node before we connect the source to its destination node.
function createAnalyser(source) {
//create analyser node
analyser = audioContext.createAnalyser();
//connect to source
source.connect(analyzer);
//pipe to speakers
analyser.connect(audioContext.destination);
}
The data I’m really interested in here is frequency. Later we could look into amplitude or time, but for now I’m going to stick with frequency.
The analyser node gives us frequency data via the getFrequencyByteData method.
Don’t forget to count!
To collect the data from the getFrequencyByteData method, we need to pass in an empty array (a JavaScript typed array is ideal). But how do we know how many items the array will need when we create it?
This is really up to us and how high the resolution of frequencies we want to analyse is. Remember we talked about sampling the waveform; this happens at a certain rate (sample rate) which you can find out via the audio context’s sampleRate attribute. This is good to bear in mind when you’re thinking about your resolution of frequencies.
var sampleRate = audioContext.sampleRate;
Let’s say your file sample rate is 48,000, making the maximum frequency in the file 24,000Hz (thanks to a wonderful theorem from Dr Harry Nyquist, the maximum frequency in the file is always half the sample rate). The analyser array we’re creating will contain frequencies up to this point. This is ideal as the human ear hears the range 0–20,000hz.
So, if we create an array which has 2,400 items, each frequency recorded will be 10Hz apart. However, we are going to create an array which is half the size of the FFT (fast Fourier transform), which in this case is 2,048 which is the default. You can set it via the fftSize property.
//set our FFT size
analyzer.fftSize = 2048;
//create an empty array with 1024 items
var frequencyData = new Uint8Array(1024);
So, with an array of 1,024 items, and a frequency range of 24,000Hz, we know each item is 24,000 ÷ 1,024 = 23.44Hz apart.
The thing is, we also want that array to be updated constantly. We could use the setInterval or setTimeout methods for this; however, I prefer the new and shiny requestAnimationFrame.
function update() {
//constantly getting feedback from data
requestAnimationFrame(update);
analyzer.getByteFrequencyData(frequencyData);
}
Putting it all together
Sweet sticks! Now we have an array of frequencies from the sound we loaded, updating as the sound plays. Now we want that data to trigger our animation from earlier.
We can easily pause and run our CSS animation from JavaScript:
element.style.webkitAnimationPlayState = "paused";
element.style.webkitAnimationPlayState = "running";
Unfortunately, this may not be ideal as our animation might be a whole heap longer than just a flashing light. We may want to target specific points within that animation to have it stop and start in a visually pleasing way and perhaps not smack bang in the middle.
There is no really easy way to do this at the moment as Zach Saucier explains in this wonderful article. It takes some jiggery pokery with setInterval to try to ascertain how far through the CSS animation you are in percentage terms.
This seems a bit much for our proof of concept, so let’s backtrack a little. We know by the animation we’ve created which CSS properties we want to change. This is pretty easy to do directly with JavaScript.
element.style.opacity = "1";
element.style.opacity = "0.2";
So let’s start putting it all together. For this example I want to trigger each light as a different frequency plays. For this, I’ll loop through the HTML elements and change the opacity style if the frequency gain goes over a certain threshold.
//get light elements
var lights = document.getElementsByTagName('i');
var totalLights = lights.length;
for (var i=0; i<totalLights; i++) {
//get frequencyData key
var freqDataKey = i*8;
//if gain is over threshold for that frequency animate light
if (frequencyData[freqDataKey] > 160){
//start animation on element
lights[i].style.opacity = "1";
} else {
lights[i].style.opacity = "0.2";
}
}
See all the code in action here. I suggest viewing in a modern browser :)
Awesome! It is true — we can VJ in our browser!
Let’s dance!
So, let’s start to expand this simple example. First, I feel the need to make lots of lights, rather than just a few. Also, maybe we should try a sound file more suited to gigs or clubs.
Check it out!
I don’t know about you, but I’m pretty excited — that’s just a bit of HTML, CSS and JavaScript!
The other thing to think about, of course, is the sound that you would get at a venue. We don’t want to load sound from a file, but rather pick up on what is playing in real time. The easiest way to do this, I’ve found, is to capture what my laptop’s mic is picking up and piping that back into the audio context. We can do this by using getUserMedia.
Let’s include this in this demo. If you make some noise while viewing the demo, the lights will start to flash.
And relax :)
There you have it. Sit back, play some music and enjoy the Winamp like experience in front of you.
So, where do we go from here? I already have a wealth of ideas. We haven’t started with canvas, SVG or the 3-D features of CSS. There are other things we can detect from the audio as well. And yes, OK, it’s questionable whether the browser is the best environment for this. For one, I’m using a whole bunch of nonsensical HTML elements (maybe each animation could be held within a web component in the future). But hey, it’s fun, and it looks cool and sometimes I think it’s OK to just dance. |
2013 |
Ruth John |
ruthjohn |
2013-12-02T00:00:00+00:00 |
https://24ways.org/2013/make-your-browser-dance/ |
code |
| 30 |
Making Sites More Responsive, Responsibly |
With digital projects we’re used to shifting our thinking to align with our target audience. We may undertake research, create personas, identify key tasks, or observe usage patterns, with our findings helping to refine our ongoing creations. A product’s overall experience can make or break its success, and when it comes to defining these experiences our development choices play a huge role alongside more traditional user-focused activities.
The popularisation of responsive web design is a great example of how we are able to shape the web’s direction through using technology to provide better experiences. If we think back to the move from table-based layouts to CSS, initially our clients often didn’t know or care about the difference in these approaches, but we did. Responsive design was similar in this respect – momentum grew through the web industry choosing to use an approach that we felt would give a better experience, and which was more future-friendly.
We tend to think of responsive design as a means of displaying content appropriately across a range of devices, but the technology and our implementation of it can facilitate much more. A responsive layout not only helps your content work when the newest smartphone comes out, but it also ensures your layout suitably adapts if a visually impaired user drastically changes the size of the text.
The 24 ways site at 400% on a Retina MacBook Pro displays a layout more typically used for small screens.
When we think more broadly, we realise that our technical choices and approaches to implementation can have knock-on effects for the greater good, and beyond our initial target audiences. We can make our experiences more responsive to people’s needs, enhancing their usability and accessibility along the way.
Being responsibly responsive
Of course, when we think about being more responsive, there’s a fine line between creating useful functionality and becoming intrusive and overly complex. In the excellent Responsible Responsive Design, Scott Jehl states that:
A responsible responsive design equally considers the following throughout a project:
Usability: The way a website’s user interface is presented to the user, and how that UI responds to browsing conditions and user interactions.
Access: The ability for users of all devices, browsers, and assistive technologies to access and understand a site’s features and content.
Sustainability: The ability for the technology driving a site or application to work for devices that exist today and to continue to be usable and accessible to users, devices, and browsers in the future.
Performance: The speed at which a site’s features and content are perceived to be delivered to the user and the efficiency with which they operate within the user interface.
Scott’s book covers these ideas in a lot more detail than I’ll be able to here (put it on your Christmas list if it’s not there already), but for now let’s think a bit more about our roles as digital creators and the power this gives us.
Our choices around technology and the decisions we have to make can be extremely wide-ranging. Solutions will vary hugely depending on the needs of each project, though we can further explore the concept of making our creations more responsive through the use of humble web technologies.
The power of the web
We all know that under the HTML5 umbrella are some great new capabilities, including a number of JavaScript APIs such as geolocation, web audio, the file API and many more. We often use these to enhance the functionality of our sites and apps, to add in new features, or to facilitate device-specific interactions.
You’ll have seen articles with flashy titles such as “Top 5 JavaScript APIs You’ve Never Heard Of!”, which you’ll probably read, think “That’s quite cool”, yet never use in any real work.
There is great potential for technologies like these to be misused, but there are also great prospects for them to be used well to enhance experiences. Let’s have a look at a few examples you may not have considered.
Offline first
When we make websites, many of us follow a process which involves user stories – standardised snippets of context explaining who needs what, and why.
“As a student I want to pay online for my course so I don’t have to visit the college in person.”
“As a retailer I want to generate unique product codes so I can manage my stock.”
We very often focus heavily on what needs doing, but may not consider carefully how it will be done. As in Scott’s list, accessibility is extremely important, not only in terms of providing a great experience to users of assistive technologies, but also to make your creation more accessible in the general sense – including under different conditions.
Offline first is yet another ‘first’ methodology (my personal favourite being ‘tea first’), which encourages us to develop so that connectivity itself is an enhancement – letting users continue with tasks even when they’re offline. Despite the rapid growth in public Wi-Fi, if we consider data costs and connectivity in developing countries, our travel habits with planes, underground trains and roaming (or simply if you live in the UK’s signal-barren East Anglian wilderness as I do), then you’ll realise that connectivity isn’t as ubiquitous as our internet-addled brains would make us believe. Take a scenario that I’m sure we’re all familiar with – the digital conference. Your venue may be in a city served by high-speed networks, but after overloading capacity with a full house of hashtag-hungry attendees, each carrying several devices, then everyone’s likely to be offline after all. Wouldn’t it be better if we could do something like this instead?
Someone visits our conference website.
On this initial run, some assets may be cached for future use: the conference schedule, the site’s CSS, photos of the speakers.
When the attendee revisits the site on the day, the page shell loads up from the cache.
If we have cached content (our session timetable, speaker photos or anything else), we can load it directly from the cache. We might then try to update this, or get some new content from the internet, but the conference attendee already has a base experience to use.
If we don’t have something cached already, then we can try grabbing it online.
If for any reason our requests for new content fail (we’re offline), then we can display a pre-cached error message from the initial load, perhaps providing our users with alternative suggestions from what is cached.
There are a number of ways we can make something like this, including using the application cache (AppCache) if you’re that way inclined. However, you may want to look into service workers instead. There are also some great resources on Offline First! if you’d like to find out more about this.
Building in offline functionality isn’t necessarily about starting offline first, and it’s also perfectly possible to retrofit sites and apps to catch offline scenarios, but this kind of graceful degradation can end up being more complex than if we’d considered it from the start. By treating connectivity as an enhancement, we can improve the experience and provide better performance than we can when waiting to counter failures. Our websites can respond to connectivity and usage scenarios, on top of adapting how we present our content. Thinking in this way can enhance each point in Scott’s criteria.
As I mentioned, this isn’t necessarily the kind of development choice that our clients will ask us for, but it’s one we may decide is simply the right way to build based on our project, enhancing the experience we provide to people, and making it more responsive to their situation.
Even more accessible
We’ve looked at accessibility in terms of broadening when we can interact with a website, but what about how? Our user stories and personas are often of limited use. We refer in very general terms to students, retailers, and sometimes just users. What if we have a student whose needs are very different from another student? Can we make our sites even more usable and accessible through our development choices?
Again using JavaScript to illustrate this concept, we can do a lot more with the ways people interact with our websites, and with the feedback we provide, than simply accepting keyboard, mouse and touch inputs and displaying output on a screen.
Input
Ambient light detection is one of those features that looks great in simple demos, but which we struggle to put to practical use. It’s not new – many satnav systems automatically change the contrast for driving at night or in tunnels, and our laptops may alter the screen brightness or keyboard backlighting to better adapt to our surroundings. Using web technologies we can adapt our presentation to be better suited to ambient light levels.
If our device has an appropriate light sensor and runs a browser that supports the API, we can grab the ambient light in units using ambient light events, in JavaScript. We may then change our presentation based on different bandings, perhaps like this:
window.addEventListener('devicelight', function(e) {
var lux = e.value;
if (lux < 50) {
//Change things for dim light
}
if (lux >= 50 && lux <= 10000) {
//Change things for normal light
}
if (lux > 10000) {
//Change things for bright light
}
});
Live demo (requires light sensor and supported browser).
Soon we may also be able to do such detection through CSS, with light-level being cited in the Media Queries Level 4 specification. If that becomes the case, it’ll probably look something like this:
@media (light-level: dim) {
/*Change things for dim light*/
}
@media (light-level: normal) {
/*Change things for normal light*/
}
@media (light-level: washed) {
/*Change things for bright light*/
}
While we may be quick to dismiss this kind of detection as being a gimmick, it’s important to consider that apps such as Light Detector, listed on Apple’s accessibility page, provide important context around exactly this functionality.
“If you are blind, Light Detector helps you to be more independent in many daily activities. At home, point your iPhone towards the ceiling to understand where the light fixtures are and whether they are switched on. In a room, move the device along the wall to check if there is a window and where it is. You can find out whether the shades are drawn by moving the device up and down.”
everywaretechnologies.com/apps/lightdetector
Input can be about so much more than what we enter through keyboards. Both an ever increasing amount of available sensors and more APIs being supported by the major browsers will allow us to cater for more scenarios and respond to them accordingly. This can be as complex or simple as you need; for instance, while x-webkit-speech has been deprecated, the web speech API is available for a number of browsers, and research into sign language detection is also being performed by organisations such as Microsoft.
Output
Web technologies give us some great enhancements around input, allowing us to adapt our experiences accordingly. They also provide us with some nice ways to provide feedback to users.
When we play video games, many of our modern consoles come with the ability to have rumble effects on our controller pads. These are a great example of an enhancement, as they provide a level of feedback that is entirely optional, but which can give a great deal of extra information to the player in the right circumstances, and broaden the scope of our comprehension beyond what we’re seeing and hearing.
Haptic feedback is possible on the web as well. We could use this in any number of responsible applications, such as alerting a user to changes or using different patterns as a communication mechanism. If you find yourself in a pickle, here’s how to print out SOS in Morse code through the vibration API. The following code indicates the length of vibration in milliseconds, interspersed by pauses in milliseconds.
navigator.vibrate([100, 300, 100, 300, 100, 300, 600, 300, 600, 300, 600, 300, 100, 300, 100, 300, 100]);
Live demo (requires supported browser)
With great power…
What you’ve no doubt come to realise by now is that these are just more examples of progressive enhancement, whose inclusion will provide a better experience if the capabilities are available, but which we should not rely on. This idea isn’t new, but the most important thing to remember, and what I would like you to take away from this article, is that it is up to us to decide to include these kind of approaches within our projects – if we don’t root for them, they probably won’t happen. This is where our professional responsibility comes in.
We won’t necessarily be asked to implement solutions for the scenarios above, but they illustrate how we can help to push the boundaries of experiences. Maybe we’ll have to switch our thinking about how we build, but we can create more usable products for a diverse range of people and usage scenarios through the choices we make around technology. Let’s stop thinking simply in terms of features inside a narrow view of our target users, and work out how we can extend these to cater for a wider set of situations.
When you plan your next digital project, consider the power of the web and the enhancements we can use, and try to make your projects even more responsive and responsible. |
2014 |
Sally Jenkinson |
sallyjenkinson |
2014-12-10T00:00:00+00:00 |
https://24ways.org/2014/making-sites-more-responsive-responsibly/ |
code |
| 136 |
Making XML Beautiful Again: Introducing Client-Side XSL |
Remember that first time you saw XML and got it? When you really understood what was possible and the deep meaning each element could carry? Now when you see XML, it looks ugly, especially when you navigate to a page of XML in a browser. Well, with every modern browser now supporting XSL 1.0, I’m going to show you how you can turn something as simple as an ATOM feed into a customised page using a browser, Notepad and some XSL.
What on earth is this XSL?
XSL is a family of recommendations for defining XML document transformation and presentation. It consists of three parts:
XSLT 1.0 – Extensible Stylesheet Language Transformation, a language for transforming XML
XPath 1.0 – XML Path Language, an expression language used by XSLT to access or refer to parts of an XML document. (XPath is also used by the XML Linking specification)
XSL-FO 1.0 – Extensible Stylesheet Language Formatting Objects, an XML vocabulary for specifying formatting semantics
XSL transformations are usually a one-to-one transformation, but with newer versions (XSL 1.1 and XSL 2.0) its possible to create many-to-many transformations too. So now you have an overview of XSL, on with the show…
So what do I need?
So to get going you need a browser an supports client-side XSL transformations such as Firefox, Safari, Opera or Internet Explorer. Second, you need a source XML file – for this we’re going to use an ATOM feed from Flickr.com. And lastly, you need an editor of some kind. I find Notepad++ quick for short XSLs, while I tend to use XMLSpy or Oxygen for complex XSL work.
Because we’re doing a client-side transformation, we need to modify the XML file to tell it where to find our yet-to-be-written XSL file. Take a look at the source XML file, which originates from my Flickr photos tagged sky, in ATOM format.
The top of the ATOM file now has an additional <?xml-stylesheet /> instruction, as can been seen on Line 2 below. This instructs the browser to use the XSL file to transform the document.
<?xml version="1.0" encoding="utf-8" standalone="yes"?>
<?xml-stylesheet type="text/xsl" href="flickr_transform.xsl"?>
<feed xmlns="http://www.w3.org/2005/Atom"
xmlns:dc="http://purl.org/dc/elements/1.1/">
Your first transformation
Your first XSL will look something like this:
<?xml version="1.0" encoding="utf-8"?>
<xsl:stylesheet version="1.0"
xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
xmlns:atom="http://www.w3.org/2005/Atom"
xmlns:dc="http://purl.org/dc/elements/1.1/">
<xsl:output method="html" encoding="utf-8"/>
</xsl:stylesheet>
This is pretty much the starting point for most XSL files. You will notice the standard XML processing instruction at the top of the file (line 1). We then switch into XSL mode using the XSL namespace on all XSL elements (line 2). In this case, we have added namespaces for ATOM (line 4) and Dublin Core (line 5). This means the XSL can now read and understand those elements from the source XML.
After we define all the namespaces, we then move onto the xsl:output element (line 6). This enables you to define the final method of output. Here we’re specifying html, but you could equally use XML or Text, for example. The encoding attributes on each element do what they say on the tin. As with all XML, of course, we close every element including the root.
The next stage is to add a template, in this case an <xsl:template /> as can be seen below:
<?xml version="1.0" encoding="utf-8"?>
<xsl:stylesheet version="1.0"
xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
xmlns:atom="http://www.w3.org/2005/Atom"
xmlns:dc="http://purl.org/dc/elements/1.1/">
<xsl:output method="html" encoding="utf-8"/>
<xsl:template match="/">
<html>
<head>
<title>Making XML beautiful again : Transforming ATOM</title>
</head>
<body>
<xsl:apply-templates select="/atom:feed"/>
</body>
</html>
</xsl:template>
</xsl:stylesheet>
The beautiful thing about XSL is its English syntax, if you say it out loud it tends to make sense.
The / value for the match attribute on line 8 is our first example of XPath syntax. The expression / matches any element – so this <xsl:template/> will match against any element in the document. As the first element in any XML document is the root element, this will be the one matched and processed first.
Once we get past our standard start of a HTML document, the only instruction remaining in this <xsl:template/> is to look for and match all <atom:feed/> elements using the <xsl:apply-templates/> in line 14, above.
<?xml version="1.0" encoding="utf-8"?>
<xsl:stylesheet version="1.0"
xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
xmlns:atom="http://www.w3.org/2005/Atom"
xmlns:dc="http://purl.org/dc/elements/1.1/">
<xsl:output method="html" encoding="utf-8"/>
<xsl:template match="/">
<xsl:apply-templates select="/atom:feed"/>
</xsl:template>
<xsl:template match="/atom:feed">
<div id="content">
<h1>
<xsl:value-of select="atom:title"/>
</h1>
<p>
<xsl:value-of select="atom:subtitle"/>
</p>
<ul id="entries">
<xsl:apply-templates select="atom:entry"/>
</ul>
</div>
</xsl:template>
</xsl:stylesheet>
This new template (line 12, above) matches <feed/> and starts to write the new HTML elements out to the output stream. The <xsl:value-of/> does exactly what you’d expect – it finds the value of the item specifed in its select attribute. With XPath you can select any element or attribute from the source XML.
The last part is a repeat of the now familiar <xsl:apply-templates/> from before, but this time we’re using it inside of a called template. Yep, XSL is full of recursion…
<xsl:template match="atom:entry">
<li class="entry">
<h2>
<a href="{atom:link/@href}">
<xsl:value-of select="atom:title"/>
</a>
</h2>
<p class="date">
(<xsl:value-of select="substring-before(atom:updated,'T')"/>)
</p>
<p class="content">
<xsl:value-of select="atom:content" disable-output-escaping="yes"/>
</p>
<xsl:apply-templates select="atom:category"/>
</li>
</xsl:template>
The <xsl:template/> which matches atom:entry (line 1) occurs every time there is a <entry/> element in the source XML file. So in total that is 20 times, this is naturally why XSLT is full of recursion. This <xsl:template/> has been matched and therefore called higher up in the document, so we can start writing list elements directly to the output stream. The first part is simply a <h2/> with a link wrapped within it (lines 3-7). We can select attributes using XPath using @.
The second part of this template selects the date, but performs a XPath string function on it. This means that we only get the date and not the time from the string (line 9). This is achieved by getting only the part of the string that exists before the T.
Regular Expressions are not part of the XPath 1.0 string functions, although XPath 2.0 does include them. Because of this, in XSL we tend to rely heavily on the available XML output.
The third part of the template (line 12) is a <xsl:value-of/> again, but this time we use an attribute of <xsl:value-of/> called disable output escaping to turn escaped characters back into XML.
The very last section is another <xsl:apply-template/> call, taking us three templates deep. Do not worry, it is not uncommon to write XSL which go 20 or more templates deep!
<xsl:template match="atom:category">
<xsl:for-each select=".">
<xsl:element name="a">
<xsl:attribute name="rel">
<xsl:text>tag</xsl:text>
</xsl:attribute>
<xsl:attribute name="href">
<xsl:value-of select="concat(@scheme, @term)"/>
</xsl:attribute>
<xsl:value-of select="@term"/>
</xsl:element>
<xsl:text> </xsl:text>
</xsl:for-each>
</xsl:template>
In our final <xsl:template/>, we see a combination of what we have done before with a couple of twists. Once we match atom:category we then count how many elements there are at that same level (line 2). The XPath . means ‘self’, so we count how many category elements are within the <entry/> element.
Following that, we start to output a link with a rel attribute of the predefined text, tag (lines 4-6). In XSL you can just type text, but results can end up with strange whitespace if you do (although there are ways to simply remove all whitespace).
The only new XPath function in this example is concat(), which simply combines what XPaths or text there might be in the brackets. We end the output for this tag with an actual tag name (line 10) and we add a space afterwards (line 12) so it won’t touch the next tag. (There are better ways to do this in XSL using the last() XPath function).
After that, we go back to the <xsl:for-each/> element again if there is another category element, otherwise we end the <xsl:for-each/> loop and end this <xsl:template/>.
A touch of style
Because we’re using recursion through our templates, you will find this is the end of the templates and the rest of the XML will be ignored by the parser. Finally, we can add our CSS to finish up. (I have created one for Flickr and another for News feeds)
<style type="text/css" media="screen">@import "flickr_overview.css?v=001";</style>
So we end up with a nice simple to understand but also quick to write XSL which can be used on ATOM Flickr feeds and ATOM News feeds. With a little playing around with XSL, you can make XML beautiful again.
All the files can be found in the zip file (14k) |
2006 |
Ian Forrester |
ianforrester |
2006-12-07T00:00:00+00:00 |
https://24ways.org/2006/beautiful-xml-with-xsl/ |
code |
| 247 |
Managing Flow and Rhythm with CSS Custom Properties |
An important part of designing user interfaces is creating consistent vertical rhythm between elements. Creating consistent, predictable space doesn’t just make your web pages and views look better, but it can also improve the scan-ability.
Browsers ship with default CSS and these styles often create consistent rhythm for flow elements out of the box. The problem is though that we often reset these styles with a reset. Elements such as <div> and <section> also have no default margin or padding associated with them.
I’ve tried all sorts of weird and wonderful techniques to find a balance between using inherited CSS while also levelling the playing field for component driven front-ends with very little success. This experimentation is how I landed on the flow utility, though and I’m going to show you how it works. Let’s dive in!
The Flow utility
With the ever-growing number of folks working with component libraries and design systems, we could benefit from a utility that creates space for us, only when it’s appropriate to do so. The problem with my previous attempts at fixing this is that the spacing values were very rigid.
That’s fine for 90% of contexts, but sometimes, it’s handy to be able to tweak the values based on the exact context of your component. This is where CSS Custom Properties come in handy.
The code
.flow {
--flow-space: 1em;
}
.flow > * + * {
margin-top: var(--flow-space);
}
What this code does is enable you to add a class of flow to an element which will then add margin-top to sibling elements within that element. We use the lobotomised owl selector to select these siblings. This approach enables an almost anonymous and automatic system which is ideal for component library based front-ends where components probably don’t have any idea what surrounds them.
The other important part of this utility is the usage of the --flow-space custom property. We define it in the .flow component and each element within it will be spaced by --flow-space, by default. The beauty about setting this as a custom property is that custom properties also participate in the cascade, so we can utilise specificity to change it if we need it. Pretty cool, right? Let’s look at some examples.
A basic example
See the Pen CSS Flow Utility: Basic implementation by Andy Bell (@hankchizljaw) on CodePen.
https://codepen.io/hankchizljaw/pen/LXqerj
What we’ve got in this example is some basic HTML content that has a class of flow on the parent article element. Because there’s a very heavy-handed reset added as a dependency, all of the content would have been squished together without the flow utility.
Because our --flow-space custom property is set to 1em, the space between elements is 1X the font size of the element in question. This means that a <h2> in this context has a calculated margin-top value of 28.8px, because it has an assigned font size of 1.8rem. If we were to globally change the --flow-space value to 1.1em for example, we’d affect everything because margin values would be calculated as 1.1X the font size.
This example looks great because using font size as the basis of rhythm works really well. What if we wanted to to tweak certain elements within this article, though?
See the Pen CSS Flow Utility: Tweaked Basic implementation by Andy Bell (@hankchizljaw) on CodePen.
https://codepen.io/hankchizljaw/pen/qQgxaY
I like lots of whitespace with my article layouts, so the 1em space isn’t going to cut it for all elements. I like to provide plenty of space between headed sections, so I increase the --flow-space in these instances:
h2 {
--flow-space: 3rem;
}
Notice also how I also switch over to using rem units? I want to make sure that these overrides are always based on the root font size. This is a personal preference of mine and you can use whatever units you want. Just be aware that it’s better for accessibility to use flexible units like em, rem and %, so that a user’s font size preferences are honoured.
A more advanced example
Although the flow utility is super useful for a plethora of contexts, it really shines when working with a few unrelated components. Instead of having to write specific layout CSS just for your particular context, you can use flow and --flow-space to create predictable and contextual space.
See the Pen CSS Flow Utility: Unrelated components by Andy Bell (@hankchizljaw) on CodePen.
https://codepen.io/hankchizljaw/pen/ZmPGyL
In this example, we’ve got ourselves a little prototype layout that features a media element, followed by a grid of features. By using flow, it was really quick and easy to generate space between those two main elements. It was also easy to create space within the components. For example, I added it to the .media__content element, so that the article’s content would space itself:
<article class="media__content flow">
...
</article>
Something to remember though: the custom properties cascade in the same way that other CSS values do, so you’ve got to keep that in mind. We’ve got a great example of that in this example where because we’ve got the flow utility on our .features component, which has a --flow-space override: the child elements of .features will inherit that value, so we’ve had to set another value on the .features__list element.
“But what about old browsers?”, I hear you cry
We’re using CSS Custom Properties that at the time of writing, have about 88% support. One thing we can do to remedy the other 12% of browsers is to set a default, traditional margin-top value of 1em, so it calculates itself based on the element’s font-size:
.flow {
--flow-space: 1em;
}
.flow > * + * {
margin-top: 1em;
margin-top: var(--flow-space);
}
Thanks to the cascading and declarative nature of CSS, we can set that default margin-top value and then immediately set it to use the custom property instead. Browsers that understand Custom Properties will automatically apply them—those that don’t will ignore them. Yay for the cascade and progressive enhancement!
Wrapping up
This tiny little utility can bring great power for when you want to consistently space elements, vertically. It also—thanks to the power of the modern web—allows us to create contextual overrides without creating modifier classes or shame CSS.
If you’ve got other methods of doing this sort of work, please let me know on Twitter. I’d love to see what you’re working on! |
2018 |
Andy Bell |
andybell |
2018-12-07T00:00:00+00:00 |
https://24ways.org/2018/managing-flow-and-rhythm-with-css-custom-properties/ |
code |
| 143 |
Marking Up a Tag Cloud |
Everyone’s doing it.
The problem is, everyone’s doing it wrong.
Harsh words, you might think. But the crimes against decent markup are legion in this area. You see, I’m something of a markup and semantics junkie. So I’m going to analyse some of the more well-known tag clouds on the internet, explain what’s wrong, and then show you one way to do it better.
del.icio.us
I think the first ever tag cloud I saw was on del.icio.us. Here’s how they mark it up.
<div class="alphacloud">
<a href="/tag/.net" class="lb s2">.net</a>
<a href="/tag/advertising" class=" s3">advertising</a>
<a href="/tag/ajax" class=" s5">ajax</a>
...
</div>
Unfortunately, that is one of the worst examples of tag cloud markup I have ever seen. The page states that a tag cloud is a list of tags where size reflects popularity. However, despite describing it in this way to the human readers, the page’s author hasn’t described it that way in the markup. It isn’t a list of tags, just a bunch of anchors in a <div>. This is also inaccessible because a screenreader will not pause between adjacent links, and in some configurations will not announce the individual links, but rather all of the tags will be read as just one link containing a whole bunch of words. Markup crime number one.
Flickr
Ah, Flickr. The darling photo sharing site of the internet, and the biggest blind spot in every standardista’s vision. Forgive it for having atrocious markup and sometimes confusing UI because it’s just so much damn fun to use. Let’s see what they do.
<p id="TagCloud">
<a href="/photos/tags/06/" style="font-size: 14px;">06</a>
<a href="/photos/tags/africa/" style="font-size: 12px;">africa</a>
<a href="/photos/tags/amsterdam/" style="font-size: 14px;">amsterdam</a>
...
</p>
Again we have a simple collection of anchors like del.icio.us, only this time in a paragraph. But rather than using a class to represent the size of the tag they use an inline style. An inline style using a pixel-based font size. That’s so far away from the goal of separating style from content, they might as well use a <font> tag. You could theoretically parse that to extract the information, but you have more work to guess what the pixel sizes represent. Markup crime number two (and extra jail time for using non-breaking spaces purely for visual spacing purposes.)
Technorati
Ah, now. Here, you’d expect something decent. After all, the Overlord of microformats and King of Semantics Tantek Çelik works there. Surely we’ll see something decent here?
<ol class="heatmap">
<li><em><em><em><em><a href="/tag/Britney+Spears">Britney Spears</a></em></em></em></em></li>
<li><em><em><em><em><em><em><em><em><em><a href="/tag/Bush">Bush</a></em></em></em></em></em></em></em></em></em></li>
<li><em><em><em><em><em><em><em><em><em><em><em><em><em><a href="/tag/Christmas">Christmas</a></em></em></em></em></em></em></em></em></em></em></em></em></em></li>
...
<li><em><em><em><em><em><em><a href="/tag/SEO">SEO</a></em></em></em></em></em></em></li>
<li><em><em><em><em><em><em><em><em><em><em><em><em><em><em><em><a href="/tag/Shopping">Shopping</a></em></em></em></em></em></em></em></em></em></em></em></em></em></em></em></li>
...
</ol>
Unfortunately it turns out not to be that decent, and stop calling me Shirley. It’s not exactly terrible code. It does recognise that a tag cloud is a list of links. And, since they’re in alphabetical order, that it’s an ordered list of links. That’s nice. However … fifteen nested <em> tags? FIFTEEN? That’s emphasis for you. Yes, it is parse-able, but it’s also something of a strange way of looking at emphasis. The HTML spec states that <em> is emphasis, and <strong> is for stronger emphasis. Nesting <em> tags seems counter to the idea that different tags are used for different levels of emphasis. Plus, if you had a screen reader that stressed the voice for emphasis, what would it do? Shout at you? Markup crime number three.
So what should it be?
As del.icio.us tells us, a tag cloud is a list of tags where the size that they are rendered at contains extra information. However, by hiding the extra context purely within the CSS or the HTML tags used, you are denying that context to some users. The basic assumption being made is that all users will be able to see the difference between font sizes, and this is demonstrably false.
A better way to code a tag cloud is to put the context of the cloud within the content, not the markup or CSS alone. As an example, I’m going to take some of my favourite flickr tags and put them into a cloud which communicates the relative frequency of each tag.
To start with a tag cloud in its most basic form is just a list of links. I am going to present them in alphabetical order, so I’ll use an ordered list. Into each list item I add the number of photos I have with that particular tag. The tag itself is linked to the page on flickr which contains those photos. So we end up with this first example. To display this as a traditional tag cloud, we need to alter it in a few ways:
The items need to be displayed next to each other, rather than one-per-line
The context information should be hidden from display (but not from screen readers)
The tag should link to the page of items with that tag
Displaying the items next to each other simply means setting the display of the list elements to inline. The context can be hidden by wrapping it in a <span> and then using the off-left method to hide it. And the link just means adding an anchor (with rel="tag" for some extra microformats bonus points). So, now we have a simple collection of links in our second example.
The last stage is to add the sizes. Since we already have context in our content, the size is purely for visual rendering, so we can just use classes to define the different sizes. For my example, I’ll use a range of class names from not-popular through ultra-popular, in order of smallest to largest, and then use CSS to define different font sizes. If you preferred, you could always use less verbose class names such as size1 through size6. Anyway, adding some classes and CSS gives us our final example, a semantic and more accessible tag cloud. |
2006 |
Mark Norman Francis |
marknormanfrancis |
2006-12-09T00:00:00+00:00 |
https://24ways.org/2006/marking-up-a-tag-cloud/ |
code |
| 240 |
My CSS Wish List |
I love Christmas. I love walking around the streets of London, looking at the beautifully decorated windows, seeing the shiny lights that hang above Oxford Street and listening to Christmas songs.
I’m not going to lie though. Not only do I like buying presents, I love receiving them too. I remember making long lists that I would send to Father Christmas with all of the Lego sets I wanted to get. I knew I could only get one a year, but I would spend days writing the perfect list.
The years have gone by, but I still enjoy making wish lists. And I’ll tell you a little secret: my mum still asks me to send her my Christmas list every year.
This time I’ve made my CSS wish list. As before, I’d be happy with just one present.
Before I begin…
… this list includes:
things that don’t exist in the CSS specification (if they do, please let me know in the comments – I may have missed them);
others that are in the spec, but it’s incomplete or lacks use cases and examples (which usually means that properties haven’t been implemented by even the most recent browsers).
Like with any other wish list, the further down I go, the more unrealistic my expectations – but that doesn’t mean I can’t wish. Some of the things we wouldn’t have thought possible a few years ago have been implemented and our wishes fulfilled (think multiple backgrounds, gradients and transformations, for example).
The list
Cross-browser implementation of font-size-adjust
When one of the fall-back fonts from your font stack is used, rather than the preferred (first) one, you can retain the aspect ratio by using this very useful property. It is incredibly helpful when the fall-back fonts are smaller or larger than the initial one, which can make layouts look less polished.
What font-size-adjust does is divide the original font-size of the fall-back fonts by the font-size-adjust value. This preserves the x-height of the preferred font in the fall-back fonts. Here’s a simple example:
p {
font-family: Calibri, "Lucida Sans", Verdana, sans-serif;
font-size-adjust: 0.47;
}
In this case, if the user doesn’t have Calibri installed, both Lucida Sans and Verdana will keep Calibri’s aspect ratio, based on the font’s x-height. This property is a personal favourite and one I keep pointing to.
Firefox supported this property from version three. So far, it’s the only browser that does. Fontdeck provides the font-size-adjust value along with its fonts, and has a handy tool for calculating it.
More control over overflowing text
The text-overflow property lets you control text that overflows its container. The most common use for it is to show an ellipsis to indicate that there is more text than what is shown. To be able to use it, the container should have overflow set to something other than visible, and white-space: nowrap:
div {
white-space: nowrap;
width: 100%;
overflow: hidden;
text-overflow: ellipsis;
}
This, however, only works for blocks of text on a single line. In the wish list of many CSS authors (and in mine) is a way of defining text-overflow: ellipsis on a block of multiple text lines. Opera has taken the first step and added support for the -o-ellipsis-lastline property, which can be used instead of ellipsis. This property is not part of the CSS3 spec, but we could certainly make good use of it if it were…
WebKit has -webkit-line-clamp to specify how many lines to show before cutting with an ellipsis, but support is patchy at best and there is no control over where the ellipsis shows in the text. Many people have spent time wrangling JavaScript to do this for us, but the methods used are very processor intensive, and introduce a JavaScript dependency.
Indentation and hanging punctuation properties
You might notice a trend here: almost half of the items in this list relate to typography. The lack of fine-grained control over typographical detail is a general concern among designers and CSS authors. Indentation and hanging punctuation fall into this category.
The CSS3 specification introduces two new possible values for the text-indent property: each-line; and hanging. each-line would indent the first line of the block container and each line after a forced line break; hanging would invert which lines are affected by the indentation.
The proposed hanging-punctuation property would allow us to specify whether opening and closing brackets and quotes should hang outside the edge of the first and last lines. The specification is still incomplete, though, and asks for more examples and use cases.
Text alignment and hyphenation properties
Following the typographic trend of this list, I’d like to add better control over text alignment and hyphenation properties. The CSS3 module on Generated Content for Paged Media already specifies five new hyphenation-related properties (namely: hyphenate-dictionary; hyphenate-before and hyphenate-after; hyphenate-lines; and hyphenate-character), but it is still being developed and lacks examples.
In the text alignment realm, the new text-align-last property allows you to define how the last line of a block (or a line just before a forced break) is aligned, if your text is set to justify. Its value can be: start; end; left; right; center; and justify. The text-justify property should also allow you to have more control over text set to text-align: justify but, for now, only Internet Explorer supports this.
calc()
This is probably my favourite item in the list: the calc() function. This function is part of the CSS3 Values and Units module, but it has only been implemented by Firefox (4.0). To take advantage of it now you need to use the Mozilla vendor code, -moz-calc().
Imagine you have a fluid two-column layout where the sidebar column has a fixed width of 240 pixels, and the main content area fills the rest of the width available. This is how you could create that using -moz-calc():
#main {
width: -moz-calc(100% - 240px);
}
Can you imagine how many hacks and headaches we could avoid were this function available in more browsers? Transitions and animations are really nice and lovely but, for me, it’s the ability to do the things that calc() allows you to that deserves the spotlight and to be pushed for implementation.
Selector grouping with -moz-any()
The -moz-any() selector grouping has been introduced by Mozilla but it’s not part of any CSS specification (yet?); it’s currently only available on Firefox 4.
This would be especially useful with the way HTML5 outlines documents, where we can have any number of variations of several levels of headings within numerous types of containers (think sections within articles within sections…).
Here is a quick example (copied from the Mozilla blog post about the article) of how -moz-any() works. Instead of writing:
section section h1, section article h1, section aside h1,
section nav h1, article section h1, article article h1,
article aside h1, article nav h1, aside section h1,
aside article h1, aside aside h1, aside nav h1, nav section h1,
nav article h1, nav aside h1, nav nav h1, {
font-size: 24px;
}
You could simply write:
-moz-any(section, article, aside, nav)
-moz-any(section, article, aside, nav) h1 {
font-size: 24px;
}
Nice, huh?
More control over styling form elements
Some are of the opinion that form elements shouldn’t be styled at all, since a user might not recognise them as such if they don’t match the operating system’s controls. I partially agree: I’d rather put the choice in the hands of designers and expect them to be capable of deciding whether their particular design hampers or improves usability.
I would say the same idea applies to font-face: while some fear designers might go crazy and litter their web pages with dozens of different fonts, most welcome the freedom to use something other than Arial or Verdana.
There will always be someone who will take this freedom too far, but it would be useful if we could, for example, style the default Opera date picker:
<input type="date" />
or Safari’s slider control (think star movie ratings, for example):
<input type="range" min="0" max="5" step="1" value="3" />
Parent selector
I don’t think there is one CSS author out there who has never come across a case where he or she wished there was a parent selector. There have been many suggestions as to how this could work, but a variation of the child selector is usually the most popular:
article < h1 {
…
}
One can dream…
Flexible box layout
The Flexible Box Layout Module sounds a bit like magic: it introduces a new box model to CSS, allowing you to distribute and order boxes inside other boxes, and determine how the available space is shared.
Two of my favourite features of this new box model are:
the ability to redistribute boxes in a different order from the markup
the ability to create flexible layouts, where boxes shrink (or expand) to fill the available space
Let’s take a quick look at the second case. Imagine you have a three-column layout, where the first column takes up twice as much horizontal space as the other two:
<body>
<section id="main">
</section>
<section id="links">
</section>
<aside>
</aside>
</body>
With the flexible box model, you could specify it like this:
body {
display: box;
box-orient: horizontal;
}
#main {
box-flex: 2;
}
#links {
box-flex: 1;
}
aside {
box-flex: 1;
}
If you decide to add a fourth column to this layout, there is no need to recalculate units or percentages, it’s as easy as that.
Browser support for this property is still in its early stages (Firefox and WebKit need their vendor prefixes), but we should start to see it being gradually introduced as more attention is drawn to it (I’m looking at you…). You can read a more comprehensive write-up about this property on the Mozilla developer blog.
It’s easy to understand why it’s harder to start playing with this module than with things like animations or other more decorative properties, which don’t really break your layouts when users don’t see them. But it’s important that we do, even if only in very experimental projects.
Nested selectors
Anyone who has never wished they could do something like the following in CSS, cast the first stone:
article {
h1 { font-size: 1.2em; }
ul { margin-bottom: 1.2em; }
}
Even though it can easily turn into a specificity nightmare and promote redundancy in your style sheets (if you abuse it), it’s easy to see how nested selectors could be useful. CSS compilers such as Less or Sass let you do this already, but not everyone wants or can use these compilers in their projects.
Every wish list has an item that could easily be dropped. In my case, I would say this is one that I would ditch first – it’s the least useful, and also the one that could cause more maintenance problems. But it could be nice.
Implementation of the ::marker pseudo-element
The CSS Lists module introduces the ::marker pseudo-element, that allows you to create custom list item markers. When an element’s display property is set to list-item, this pseudo-element is created.
Using the ::marker pseudo-element you could create something like the following:
Footnote 1: Both John Locke and his father, Anthony Cooper, are
named after 17th- and 18th-century English philosophers; the real
Anthony Cooper was educated as a boy by the real John Locke.
Footnote 2: Parts of the plane were used as percussion instruments
and can be heard in the soundtrack.
where the footnote marker is generated by the following CSS:
li::marker {
content: "Footnote " counter(notes) ":";
text-align: left;
width: 12em;
}
li {
counter-increment: notes;
}
You can read more about how to use counters in CSS in my article from last year.
Bear in mind that the CSS Lists module is still a Working Draft and is listed as “Low priority”. I did say this wish list would start to grow more unrealistic closer to the end…
Variables
The sight of the word ‘variables’ may make some web designers shy away, but when you think of them applied to things such as repeated colours in your stylesheets, it’s easy to see how having variables available in CSS could be useful.
Think of a website where the main brand colour is applied to elements like the main text, headings, section backgrounds, borders, and so on. In a particularly large website, where the colour is repeated countless times in the CSS and where it’s important to keep the colour consistent, using variables would be ideal (some big websites are already doing this by using server-side technology).
Again, Less and Sass allow you to use variables in your CSS but, again, not everyone can (or wants to) use these.
If you are using Less, you could, for instance, set the font-family value in one variable, and simply call that variable later in the code, instead of repeating the complete font stack, like so:
@fontFamily: Calibri, "Lucida Grande", "Lucida Sans Unicode", Helvetica, Arial, sans-serif;
body {
font-family: @fontFamily;
}
Other features of these CSS compilers might also be useful, like the ability to ‘call’ a property value from another selector (accessors):
header {
background: #000000;
}
footer {
background: header['background'];
}
or the ability to define functions (with arguments), saving you from writing large blocks of code when you need to write something like, for example, a CSS gradient:
.gradient (@start:"", @end:"") {
background: -webkit-gradient(linear, left top, left bottom, from(@start), to(@end));
background: -moz-linear-gradient(-90deg,@start,@end);
}
button {
.gradient(#D0D0D0,#9F9F9F);
}
Standardised comments
Each CSS author has his or her own style for commenting their style sheets. While this isn’t a massive problem on smaller projects, where maybe only one person will edit the CSS, in larger scale projects, where dozens of hands touch the code, it would be nice to start seeing a more standardised way of commenting.
One attempt at creating a standard for CSS comments is CSSDOC, an adaptation of Javadoc (a documentation generator that extracts comments from Java source code into HTML). CSSDOC uses ‘DocBlocks’, a term borrowed from the phpDocumentor Project. A DocBlock is a human- and machine-readable block of data which has the following structure:
/**
* Short description
*
* Long description (this can have multiple lines and contain <p> tags
*
* @tags (optional)
*/
CSSDOC includes a standard for documenting bug fixes and hacks, colours, versioning and copyright information, amongst other important bits of data.
I know this isn’t a CSS feature request per se; rather, it’s just me pointing you at something that is usually overlooked but that could contribute towards keeping style sheets easier to maintain and to hand over to new developers.
Final notes
I understand that if even some of these were implemented in browsers now, it would be a long time until all vendors were up to speed. But if we don’t talk about them and experiment with what’s available, then it will definitely never happen.
Why haven’t I mentioned better browser support for existing CSS3 properties? Because that would be the same as adding chocolate to your Christmas wish list – you don’t need to ask, everyone knows you want it.
The list could go on. There are dozens of other things I would love to see integrated in CSS or further developed. These are my personal favourites: some might be less useful than others, but I’ve wished for all of them at some point.
Part of the research I did while writing this article was asking some friends what they would add to their lists; other than a couple of items I already had in mine, everything else was different. I’m sure your list would be different too. So tell me, what’s on your CSS wish list? |
2010 |
Inayaili de León Persson |
inayailideleon |
2010-12-03T00:00:00+00:00 |
https://24ways.org/2010/my-css-wish-list/ |
code |
| 335 |
Naughty or Nice? CSS Background Images |
Web Standards based development involves many things – using semantically sound HTML to provide structure to our documents or web applications, using CSS for presentation and layout, using JavaScript responsibly, and of course, ensuring that all that we do is accessible and interoperable to as many people and user agents as we can.
This we understand to be good.
And it is good.
Except when we don’t clearly think through the full implications of using those techniques.
Which often happens when time is short and we need to get things done.
Here are some naughty examples of CSS background images with their nicer, more accessible counterparts.
Transaction related messages
I’m as guilty of this as others (or, perhaps, I’m the only one that has done this, in which case this can serve as my holiday season confessional) We use lovely little icons to show status messages for a transaction to indicate if the action was successful, or was there a warning or error? For example:
“Your postal/zip code was not in the correct format.”
Notice that we place a nice little icon there, and use background colours and borders to convey a specific message: there was a problem that needs to be fixed. Notice that all of this visual information is now contained in the CSS rules for that div:
<div class="error">
<p>Your postal/zip code was not in the correct format.</p>
</div>
div.error {
background: #ffcccc url(../images/error_small.png) no-repeat 5px 4px;
color: #900;
border-top: 1px solid #c00;
border-bottom: 1px solid #c00;
padding: 0.25em 0.5em 0.25em 2.5em;
font-weight: bold;
}
Using this approach also makes it very easy to create a div.success and div.warning CSS rules meaning we have less to change in our HTML.
Nice, right?
No. Naughty.
Visual design communicates
The CSS is being used to convey very specific information. The choice of icon, the choice of background colour and borders tell us visually that there is something wrong.
With the icon as a background image – there is no way to specify any alt text for the icon, and significant meaning is lost. A screen reader user, for example, misses the fact that it is an “error.”
The solution? Ask yourself: what is the bare minimum needed to indicate there was an error? Currently in the absence of CSS there will be no icon – which (I’m hoping you agree) is critical to communicating there was an error.
The icon should be considered content and not simply presentational.
The borders and background colour are certainly much less critical – they belong in the CSS.
Lets change the code to place the image directly in the HTML and using appropriate alt text to better communicate the meaning of the icon to all users:
<div class="bettererror">
<img src="images/error_small.png" alt="Error" />
<p>Your postal/zip code was not in the correct format.</p>
</div>
div.bettererror {
background-color: #ffcccc;
color: #900;
border-top: 1px solid #c00;
border-bottom: 1px solid #c00;
padding: 0.25em 0.5em 0.25em 2.5em;
font-weight: bold;
position: relative;
min-height: 1.25em;
}
div.bettererror img {
display: block;
position: absolute;
left: 0.25em;
top: 0.25em;
padding: 0;
margin: 0;
}
div.bettererror p {
position: absolute;
left: 2.5em;
padding: 0;
margin: 0;
}
Compare these two examples of transactional messages
Status of a Record
This example is pretty straightforward. Consider the following: a real estate listing on a web site. There are three “states” for a listing: new, normal, and sold. Here’s how they look:
Example of a New Listing
Example of A Sold Listing
If we (forgive the pun) blindly apply the “use a CSS background image” technique we clearly run into problems with the new and sold images – they actually contain content with no way to specify an alternative when placed in the CSS.
In this case of the “new” image, we can use the same strategy as we used in the first example (the transaction result). The “new” image should be considered content and is placed in the HTML as part of the <h2>...</h2> that identifies the listing.
However when considering the “sold” listing, there are less changes to be made to keep the same look by leaving the “SOLD” image as a background image and providing the equivalent information elsewhere in the listing – namely, right in the heading.
For those that can’t see the background image, the status is communicated clearly and right away. A screen reader user that is navigating by heading or viewing a listing will know right away that a particular property is sold.
Of note here is that in both cases (new and sold) placing the status near the beginning of the record helps with a zoom layout as well.
Better Example of A Sold Listing
Summary
Remember: in the holiday season, its what you give that counts!! Using CSS background images is easy and saves time for you but think of the children. And everyone else for that matter…
CSS background images should only be used for presentational images, not for those that contain content (unless that content is already represented and readily available elsewhere). |
2005 |
Derek Featherstone |
derekfeatherstone |
2005-12-20T00:00:00+00:00 |
https://24ways.org/2005/naughty-or-nice-css-background-images/ |
code |
| 54 |
Putting My Patterns through Their Paces |
Over the last few years, the conversation around responsive design has shifted subtly, focusing not on designing pages, but on patterns: understanding the small, reusable elements that comprise a larger design system. And given that many of those patterns are themselves responsive, learning to manage these small layout systems has become a big part of my work.
The thing is, the more pattern-driven work I do, the more I realize my design process has changed in a number of subtle, important ways. I suppose you might even say that pattern-driven design has, in a few ways, redesigned me.
Meet the Teaser
Here’s a recent example. A few months ago, some friends and I redesigned The Toast. (It was a really, really fun project, and we learned a lot.) Each page of the site is, as you might guess, stitched together from a host of tiny, reusable patterns. Some of them, like the search form and footer, are fairly unique, and used once per page; others are used more liberally, and built for reuse. The most prevalent example of these more generic patterns is the teaser, which is classed as, uh, .teaser. (Look, I never said I was especially clever.)
In its simplest form, a teaser contains a headline, which links to an article:
Fairly straightforward, sure. But it’s just the foundation: from there, teasers can have a byline, a description, a thumbnail, and a comment count. In other words, we have a basic building block (.teaser) that contains a few discrete content types – some required, some not. In fact, very few of those pieces need to be present; to qualify as a teaser, all we really need is a link and a headline. But by adding more elements, we can build slight variations of our teaser, and make it much, much more versatile.
Nearly every element visible on this page is built out of our generic “teaser” pattern.
But the teaser variation I’d like to call out is the one that appears on The Toast’s homepage, on search results or on section fronts. In the main content area, each teaser in the list features larger images, as well as an interesting visual treatment: the byline and comment count were the most prominent elements within each teaser, appearing above the headline.
The approved visual design of our teaser, as it appears on lists on the homepage and the section fronts.
And this is, as it happens, the teaser variation that gave me pause. Back in the old days – you know, like six months ago – I probably would’ve marked this module up to match the design. In other words, I would’ve looked at the module’s visual hierarchy (metadata up top, headline and content below) and written the following HTML:
<div class="teaser">
<p class="article-byline">By <a href="#">Author Name</a></p>
<a class="comment-count" href="#">126 <i>comments</i></a>
<h1 class="article-title"><a href="#">Article Title</a></h1>
<p class="teaser-excerpt">Lorem ipsum dolor sit amet, consectetur…</p>
</div>
But then I caught myself, and realized this wasn’t the best approach.
Moving Beyond Layout
Since I’ve started working responsively, there’s a question I work into every step of my design process. Whether I’m working in Sketch, CSSing a thing, or researching a project, I try to constantly ask myself:
What if someone doesn’t browse the web like I do?
…Okay, that doesn’t seem especially fancy. (And maybe you came here for fancy.) But as straightforward as that question might seem, it’s been invaluable to so many aspects of my practice. If I’m working on a widescreen layout, that question helps me remember the constraints of the small screen; if I’m working on an interface that has some enhancements for touch, it helps me consider other input modes as I work. It’s also helpful as a reminder that many might not see the screen the same way I do, and that accessibility (in all its forms) should be a throughline for our work on the web.
And that last point, thankfully, was what caught me here. While having the byline and comment count at the top was a lovely visual treatment, it made for a terrible content hierarchy. For example, it’d be a little weird if the page was being read aloud in a speaking browser: the name of the author and the number of comments would be read aloud before the title of the article with which they’re associated.
That’s why I find it’s helpful to begin designing a pattern’s hierarchy before its layout: to move past the visual presentation in front of me, and focus on the underlying content I’m trying to support. In other words, if someone’s encountering my design without the CSS I’ve written, what should their experience be?
So I took a step back, and came up with a different approach:
<div class="teaser">
<h1 class="article-title"><a href="#">Article Title</a></h1>
<h2 class="article-byline">By <a href="#">Author Name</a></h2>
<p class="teaser-excerpt">
Lorem ipsum dolor sit amet, consectetur…
<a class="comment-count" href="#">126 <i>comments</i></a>
</p>
</div>
Much, much better. This felt like a better match for the content I was designing: the headline – easily most important element – was at the top, followed by the author’s name and an excerpt. And while the comment count is visually the most prominent element in the teaser, I decided it was hierarchically the least critical: that’s why it’s at the very end of the excerpt, the last element within our teaser. And with some light styling, we’ve got a respectable-looking hierarchy in place:
Yeah, you’re right – it’s not our final design. But from this basic-looking foundation, we can layer on a bit more complexity. First, we’ll bolster the markup with an extra element around our title and byline:
<div class="teaser">
<div class="teaser-hed">
<h1 class="article-title"><a href="#">Article Title</a></h1>
<h2 class="article-byline">By <a href="#">Author Name</a></h2>
</div>
…
</div>
With that in place, we can use flexbox to tweak our layout, like so:
.teaser-hed {
display: flex;
flex-direction: column-reverse;
}
flex-direction: column-reverse acts a bit like a change in gravity within our teaser-hed element, vertically swapping its two children.
Getting closer! But as great as flexbox is, it doesn’t do anything for elements outside our container, like our little comment count, which is, as you’ve probably noticed, still stranded at the very bottom of our teaser.
Flexbox is, as you might already know, wonderful! And while it enjoys incredibly broad support, there are enough implementations of old versions of Flexbox (in addition to plenty of bugs) that I tend to use a feature test to check if the browser’s using a sufficiently modern version of flexbox. Here’s the one we used:
var doc = document.body || document.documentElement;
var style = doc.style;
if ( style.webkitFlexWrap == '' ||
style.msFlexWrap == '' ||
style.flexWrap == '' ) {
doc.className += " supports-flex";
}
Eagle-eyed readers will note we could have used @supports feature queries to ask browsers if they support certain CSS properties, removing the JavaScript dependency. But since we wanted to serve the layout to IE we opted to write a little question in JavaScript, asking the browser if it supports flex-wrap, a property used elsewhere in the design. If the browser passes the test, then a class of supports-flex gets applied to our html element. And with that class in place, we can safely quarantine our flexbox-enabled layout from less-capable browsers, and finish our teaser’s design:
.supports-flex .teaser-hed {
display: flex;
flex-direction: column-reverse;
}
.supports-flex .teaser .comment-count {
position: absolute;
right: 0;
top: 1.1em;
}
If the supports-flex class is present, we can apply our flexbox layout to the title area, sure – but we can also safely use absolute positioning to pull our comment count out of its default position, and anchor it to the top right of our teaser. In other words, the browsers that don’t meet our threshold for our advanced styles are left with an attractive design that matches our HTML’s content hierarchy; but the ones that pass our test receive the finished, final design.
And with that, our teaser’s complete.
Diving Into Device-Agnostic Design
This is, admittedly, a pretty modest application of flexbox. (For some truly next-level work, I’d recommend Heydon Pickering’s “Flexbox Grid Finesse”, or anything Zoe Mickley Gillenwater publishes.) And for such a simple module, you might feel like this is, well, quite a bit of work. And you’d be right! In fact, it’s not one layout, but two: a lightly styled content hierarchy served to everyone, with the finished design served conditionally to the browsers that can successfully implement it. But I’ve found that thinking about my design as existing in broad experience tiers – in layers – is one of the best ways of designing for the modern web. And what’s more, it works not just for simple modules like our teaser, but for more complex or interactive patterns as well.
Open video
Even a simple search form can be conditionally enhanced, given a little layered thinking.
This more layered approach to interface design isn’t a new one, mind you: it’s been championed by everyone from Filament Group to the BBC. And with all the challenges we keep uncovering, a more device-agnostic approach is one of the best ways I’ve found to practice responsive design. As Trent Walton once wrote,
Like cars designed to perform in extreme heat or on icy roads, websites should be built to face the reality of the web’s inherent variability.
We have a weird job, working on the web. We’re designing for the latest mobile devices, sure, but we’re increasingly aware that our definition of “smartphone” is much too narrow. Browsers have started appearing on our wrists and in our cars’ dashboards, but much of the world’s mobile data flows over sub-3G networks. After all, the web’s evolution has never been charted along a straight line: it’s simultaneously getting slower and faster, with devices new and old coming online every day. With all the challenges in front of us, including many we don’t yet know about, a more device-agnostic, more layered design process can better prepare our patterns – and ourselves – for the future.
(It won’t help you get enough to eat at holiday parties, though.) |
2015 |
Ethan Marcotte |
ethanmarcotte |
2015-12-10T00:00:00+00:00 |
https://24ways.org/2015/putting-my-patterns-through-their-paces/ |
code |
| 243 |
Researching a Property in the CSS Specifications |
I frequently joke that I’m “reading the specs so you don’t have to”, as I unpack some detail of a CSS spec in a post on my blog, some documentation for MDN, or an article on Smashing Magazine. However waiting for someone like me to write an article about something is a pretty slow way to get the information you need. Sometimes people like me get things wrong, or specifications change after we write a tutorial.
What if you could just look it up yourself? That’s what you get when you learn to read the CSS specifications, and in this article my aim is to give you the basic details you need to grab quick information about any CSS property detailed in the CSS specs.
Where are the CSS Specifications?
The easiest way to see all of the CSS specs is to take a look at the Current Work page in the CSS section of the W3C Website. Here you can see all of the specifications listed, the level they are at and their status. There is also a link to the specification from this page. I explained CSS Levels in my article Why there is no CSS 4.
Who are the specifications for?
CSS specifications are for everyone who uses CSS. You might be a browser engineer - referred to as an implementor - needing to know how to implement a feature, or a web developer - referred to as an author - wanting to know how to use the feature. The fact that both parties are looking at the same document hopefully means that what the browser displays is what the web developer expected.
Which version of a spec should I look at?
There are a couple of places you might want to look. Each published spec will have the latest published version, which will have TR in the URL and can be accessed without a date (which is always the newest version) or at a date, which will be the date of that publication. If I’m referring to a particular Working Draft in an article I’ll typically link to the dated version. That way if the information changes it is possible for someone to see where I got the information from at the time of writing.
If you want the very latest additions and changes to the spec, then the Editor’s Draft is the place to look. This is the version of the spec that the editors are committing changes to. If I make a change to the Multicol spec and push it to GitHub, within a few minutes that will be live in the Editor’s Draft. So it is possible there are errors, bits of text that we are still working out and so on. The Editor’s Draft however is definitely the place to look if you are wanting to raise an issue on a spec, as it may be that the issue you are about to raise is already fixed.
If you are especially keen on seeing updates to specifications keep an eye on https://drafts.csswg.org/ as this is a list of drafts, along with the date they were last updated.
How to approach a spec
The first thing to understand is that most CSS Specifications start with the most straightforward information, and get progressively further into the weeds. For an author the initial examples and explanations are likely to be of interest, and then the property definitions and examples. Therefore, if you are looking at a vast spec, know that you probably won’t need to read all the way to the bottom, or read every section in detail.
The second thing that is useful to know about modern CSS specifications is how modularized they are. It really never is a case of finding everything you need in a single document. If we tried to do that, there would be a lot of repetition and likely inconsistency between specs. There are some key specifications that many other specifications draw on, such as:
Values and Units
Intrinsic and Extrinsic Sizing
Box Alignment
When something is defined in another specification the spec you are reading will link to it, so it is worth opening that other spec in a new tab in order that you can refer back to it as you explore.
Researching your property
As an example we will take a look at the property grid-auto-rows, this property defines row tracks in the implicit grid when using CSS Grid Layout. The first thing you will need to do is find out which specification defines this property.
You might already know which spec the property is part of, and therefore you could go directly to the spec and search using your browser or look in the navigation for the spec to find it. Alternatively, you could take a look at the CSS Property Index, which is an automatically generated list of CSS Properties.
Clicking on a property will take you to the TR version of the spec, the latest published draft, and the definition of that property in it. This definition begins with a panel detailing the syntax of this property. For grid-auto-rows, you can see that it is listed along with grid-auto-columns as these two properties are essentially identical. They take the same values and work in the same way, one for rows and the other for columns.
Value
For value we can see that the property accepts a value <track-size>. The next thing to do is to find out what that actually means, clicking will take you to where it is defined in the Grid spec.
The <track-size> value is defined as accepting various values:
<track-breadth>
minmax( <inflexible-breadth> , <track-breadth> )
fit-content( <length-percentage>
We need to head down the rabbit hole to find out what each of these mean. From here we essentially go down line by line until we have unpacked the value of track-size.
<track-breadth> is defined just below <track-size> as:
<length-percentage>
<flex>
min-content
max-content
auto
So these are all things that would be valid to use as a value for grid-auto-rows.
The first value of <length-percentage> is something you will see in many specifications as a value. It means that you can use a length unit - for example px or em - or a percentage. Some properties only accept a <length> in which case you know that you cannot use a percentage as the value. This means that you could have grid-auto-rows with any of the following values.
grid-auto-rows: 100px;
grid-auto-rows: 1em;
grid-auto-rows: 30%;
When using percentages, it is important to know what it is a percentage of. As a percentage has to resolve from something. There is text in the spec which explains how column and row percentages work.
“<percentage> values are relative to the inline size of the grid container in column grid tracks, and the block size of the grid container in row grid tracks.”
This means that in a horizontal writing mode such as when using English, a percentage when used as a track-size in grid-auto-columns would be a percentage of the width of the grid, and a percentage in grid-auto-rows a percentage of the height of the grid.
The second value of <flex> is also defined here, as “A non-negative dimension with the unit fr specifying the track’s flex factor.” This is the fr unit, and the spec links to a fuller definition of fr as this unit is only used in Grid Layout so it is therefore defined in the grid spec. We now know that a valid value would be:
grid-auto-rows: 1fr;
There is some useful information about the fr unit in this part of the spec. It is noted that the fr unit has an automatic minimum. This means that 1fr is really minmax(auto, 1fr). This is why having a number of tracks all at 1fr does not mean that all are equal sized, as a larger item in any of the tracks would have a large auto size and therefore would be larger after spare space had been distributed.
We then have min-content and max-content. These keywords can be used for track sizing and the specification defines what they mean in the context of sizing a track, representing the min and max-sizing contributions of the grid tracks. You will see that there are various terms linked in the definition, so if you do not know what these mean you can follow them to find out.
For example the spec links max-content contribution to the CSS Intrinsic and Extrinsic Sizing specification. This is one of those specs which is drawn on by many other specifications. If we follow that link we can read the definition there and follow further links to understand what each term means. The more that you read specifications the more these terms will become familiar to you. Just like learning a foreign language, at first you feel like you have to look up every little thing. After a while you remember the vocabulary.
We can now add min-content and max-content to our available values.
grid-auto-rows: min-content;
grid-auto-rows: max-content;
The final item in our list is auto. If you are familiar with using Grid Layout, then you are probably aware that an auto sized track for will grow to fit the content used. There is an interesting note here in the spec detailing that auto sized rows will stretch to fill the grid container if there is extra space and align-content or justify-content have a value of stretch. As stretch is the default value, that means these tracks stretch by default. Tracks using other types of length will not behave like this.
grid-auto-rows: auto;
So, this was the list for <track-breadth>, the next possible value is minmax( <inflexible-breadth> , <track-breadth> ). So this is telling us that we can use minmax() as a value, the final (max) value will be <track-breadth> and we have already unpacked all of the allowable values there. The first value (min) is detailed as an <inflexible-breadth>. If we look at the values for this, we discover that they are the same as <track-breadth>, minus the <flex> value:
<length-percentage>
min-content
max-content
auto
We already know what all of these do, so we can add possible minmax() values to our list of values for <track-size>.
grid-auto-rows: minmax(100px, 200px);
grid-auto-rows: minmax(20%, 1fr);
grid-auto-rows: minmax(1em, auto);
grid-auto-rows: minmax(min-content, max-content);
Finally we can use fit-content( <length-percentage>. We can see that fit-content takes a value of <length-percentage> which we already know to be either a length unit, or a percentage. The spec details how fit-content is worked out, and it essentially allows a track which acts as if you had used the max-content keyword, however the track stops growing when it hits the length passed to it.
grid-auto-rows: fit-content(200px);
grid-auto-rows: fit-content(20%);
Those are all of our possible values, and to round things off, check again at the initial <track-size> value, you can see it has a little + sign next to it, click that and you will be taken to the CSS Values and Units module to find that, “A plus (+) indicates that the preceding type, word, or group occurs one or more times.” This means that we can pass a single track size to grid-auto-rows or multiple track sizes as a space separated list. Below the box is an explanation of what happens if you pass in more than one track size:
“If multiple track sizes are given, the pattern is repeated as necessary to find the size of the implicit tracks. The first implicit grid track after the explicit grid receives the first specified size, and so on forwards; and the last implicit grid track before the explicit grid receives the last specified size, and so on backwards.”
Therefore with the following CSS, if five implicit rows were needed they would be as follows:
100px
1fr
auto
100px
1fr
.grid {
display: grid;
grid-auto-rows: 100px 1fr auto;
}
Initial
We can now move to the next line in the box, and you’ll be glad to know that it isn’t going to require as much unpacking! This simply defines the initial value for grid-auto-rows. If you do not specify anything, created rows will be auto sized. All CSS properties have an initial value that they will use if they are invoked as part of the usage of the specification they are in, but you do not set a value for them. In the case of grid-auto-rows it is used whenever rows are created in the implicit grid, so it needs to have a value to be used even if you do not set one.
Applies to
This line tells us what this property is used for. Some properties are used in multiple places. For example if you look at the definition for justify-content in the Box Alignment specification you can see it is used in multicol containers, flex containers, and grid containers. In our case the property only applies for grid containers.
Inherited
This tells us if the property can be inherited from a parent element if it is not set. In the case of grid-auto-rows it is not inherited. A property such as color is inherited, so you do not need to set it on each element.
Percentages
Are percentages allowed for this property, and if so how are they calculated. In this case we are referred to the definition for grid-template-columns and grid-template-rows where we discover that the percentage is from the corresponding dimension of the content area.
Media
This defines the media group that the property belongs to. In this case visual.
Computed Value
This details how the value is resolved. The grid-auto-rows property again refers to track sizing as defined for grid-template-columns and grid-template-rows, which tells us the computed value is as specified with lengths made absolute.
Canonical Order
If you have a property–generally a shorthand property–which takes multiple values in a set order, then those values need to be serialized in the order detailed in the grammar for that property. In general you don’t need to worry about this value in the table.
Animation Type
This details whether the property can be animated, and if so what type of animation. This is useful if you are trying to animate something and not getting the result that you expect. Note that just because something is listed in the spec as animatable does not mean that browsers will have implemented animation for that property yet!
That’s (mostly) it!
Sometimes the property will have additional examples - there is one underneath the table for grid-auto-rows. These are worth looking at as they will highlight usage of the property that the spec editor has felt could use an example. There may also be some additional text explaining anythign specific to this property.
In selecting grid-auto-rows I chose a fairly complex property in terms of the work we needed to do to unpack the value. Many properties are far simpler than this. However ultimately, even when you come across a complex value, it really is just a case of stepping through the definitions until you come to the bottom of the rabbit hole.
Being able to work out what is valid for each property is incredibly useful. It means you don’t waste time trying to use a value that doesn’t work for that property. You also may find that there are values you weren’t aware of, that solve problems for you.
Further reading
Specifications are not designed to be user manuals, and while they often contain examples, these are pretty terse as they need to be clear to demonstrate their particular point. The manual for the Web Platform is MDN Web Docs. Pairing reading a specification with the examples and information on an MDN property page such as the one for grid-auto-rows is a really great way to ensure that you have all the information and practical usage examples you might need.
You may also find useful:
Value Definition Syntax on MDN.
The MDN Glossary defines many common terms.
Understanding the CSS Property Value Syntax goes into more detail in terms of reading the syntax.
How to read W3C Specs - from 2001 but still relevant.
I hope this article has gone some way to demystify CSS specifications for you. Even if the specifications are not your preferred first stop to learn about new CSS, being able to go directly to the source and avoid having your understanding filtered by someone else, can be very useful indeed. |
2018 |
Rachel Andrew |
rachelandrew |
2018-12-14T00:00:00+00:00 |
https://24ways.org/2018/researching-a-property-in-the-css-specifications/ |
code |
| 79 |
Responsive Images: What We Thought We Needed |
If you were to read a web designer’s Christmas wish list, it would likely include a solution for displaying images responsively. For those concerned about users downloading unnecessary image data, or serving images that look blurry on high resolution displays, finding a solution has become a frustrating quest.
Having experimented with complex and sometimes devilish hacks, consensus is forming around defining new standards that could solve this problem. Two approaches have emerged.
The <picture> element markup pattern was proposed by Mat Marquis and is now being developed by the Responsive Images Community Group. By providing a means of declaring multiple sources, authors could use media queries to control which version of an image is displayed and under what conditions:
<picture width="500" height="500">
<source media="(min-width: 45em)" src="large.jpg">
<source media="(min-width: 18em)" src="med.jpg">
<source src="small.jpg">
<img src="small.jpg" alt="">
<p>Accessible text</p>
</picture>
A second proposal put forward by Apple, the srcset attribute, uses a more concise syntax intended for use with the <img> element, although it could be compatible with the <picture> element too. This would allow authors to provide a set of images, but with the decision on which to use left to the browser:
<img src="fallback.jpg" alt="" srcset="small.jpg 640w 1x, small-hd.jpg 640w 2x, med.jpg 1x, med-hd.jpg 2x ">
Enter Scrooge
Men’s courses will foreshadow certain ends, to which, if persevered in, they must lead.
Ebenezer Scrooge
Given the complexity of this issue, there’s a heated debate about which is the best option. Yet code belies a certain truth. That both feature verbose and opaque syntax, I’m not sure either should find its way into the browser – especially as alternative approaches have yet to be fully explored.
So, as if to dampen the festive cheer, here are five reasons why I believe both proposals are largely redundant.
1. We need better formats, not more markup
As we move away from designs defined with fixed pixel values, bitmap images look increasingly unsuitable. While simple images and iconography can use scalable vector formats like SVG, for detailed photographic imagery, raster formats like GIF, PNG and JPEG remain the only suitable option.
There is scope within current formats to account for varying bandwidth but this requires cooperation from browser vendors. Newer formats like JPEG2000 and WebP generate higher quality images with smaller file sizes, but aren’t widely supported.
While it’s tempting to try to solve this issue by inventing new markup, the crux of it remains at the file level.
Daan Jobsis’s experimentation with image compression strengthens this argument. He discovered that by increasing the dimensions of a JPEG image while simultaneously reducing its quality, a smaller files could be produced, with the resulting image looking just as good on both standard and high-resolution displays.
This may be a hack in lieu of a more permanent solution, but it’s applied in the right place. Easy to accomplish with existing tools and without compatibility issues, it has few downsides. Further experimentation in this area should be encouraged, with standardisation efforts more helpful if focused on developing new image formats or, preferably, extending existing ones.
2. Art direction doesn’t belong in markup
A desired benefit of the <picture> markup pattern is to allow for greater art direction. For example, rather than scaling down images on smaller displays to the point that their content is hard to discern, we could present closer crops instead:
This can be achieved with CSS of course, although with a download penalty for those parts of an image not shown. This point may be negligible, however, since in the context of adaptable layouts, these hidden areas may end up being revealed anyway.
Art direction concerns design, not content. If we wish to maintain a separation of concerns, including presentation within our markup seems misguided.
3. The size of a display has little relation to the size of an image
By using media queries, the <picture> element allows authors to choose which characteristics of the screen or viewport to query for different images to be displayed.
In developing sites at Clearleft, we have noticed that the viewport is essentially arbitrary, with the size of an image’s containing element more important. For example, look at how this grid of images may adapt at different viewport widths:
As we build more modular systems, components need to be adaptable in and of themselves. There is a case to be made for developing more contextual methods of querying, rather than those based on attributes of the display.
4. We haven’t lived with the problem long enough
A key strength of the web is that the underlying platform can be continually iterated. This can also be problematic if snap judgements are made about what constitutes an improvement.
The early history of the web is littered with such examples, be it the perceived need for blinking text or inline typographic styling. To build a platform for the future, additions to it should be carefully considered. And if we want more consistent support across browsers, burdening vendors with an ever increasing list of features seems counterproductive.
Only once the need for a new feature is sufficiently proven, should we look to standardise it. Before we could declare hover effects, rounded corners and typographic styling in CSS, we used JavaScript as a polyfill. Sure, doing so was painful, but use cases were fully explored, and the CSS specification better reflected the needs of authors.
5. Images and the web aesthetic
The srcset proposal has emerged from a company that markets its phones as being able to browse the real – yet squashed down, tapped and zoomable – web. Perhaps Apple should make its own website responsive before suggesting how the rest of us should do so.
Converserly, while the <picture> proposal has the backing of a few respected developers and designers, it was born out of the work Mat Marquis and Filament Group did for the Boston Globe. As the first large-scale responsive design, this was a landmark project that ignited the responsive web design movement and proved its worth. But it was the first.
Its design shares a vernacular to that of contemporary newspaper websites, with a columnar, image-laden and densely packed layout. Compared to more recent examples – Quartz, The Next Web and the New York Times Skimmer – it feels out of step with the future direction of news sites. In seeking out a truer aesthetic for the web in which software interfaces have greater influence, we might discover that the need for responsive images isn’t as great as originally thought.
Building for the future
With responsive design, we’ve accepted the idea that a fully fluid layout, rather than a set of fixed layouts, is best suited to the web’s unpredictable nature. Current responsive image proposals are antithetical to this approach.
We need solutions that lack complexity, are device-agnostic and work within existing workflows. Any proposal that requires different versions of the same image to be created, is likely to have to acquiesce under the pressure of reality.
While it’s easy to get distracted about the size and quality of an image, and how we might choose to serve it, often the simplest solution is not to include it at all. After years of gluttonous design practice, in which fast connections and expansive display sizes were an accepted norm, we have got use to filling pages with needless images and countless items of page furniture.
To design more adaptable experiences, the presence of every element needs to be questioned, for its existence requires additional data to be downloaded or futher complexity within a design system. Conditional loading techniques mean that the inclusion of images is no longer a binary choice, but can instead appear in a progressively enhanced manner.
So here is my proposal. Instead of spending the next year worrying about responsive images, let’s embrace the constraints of the medium, and seek out new solutions that can work within them. |
2012 |
Paul Lloyd |
paulrobertlloyd |
2012-12-11T00:00:00+00:00 |
https://24ways.org/2012/responsive-images-what-we-thought-we-needed/ |
code |
| 171 |
Rock Solid HTML Emails |
At some stage in your career, it’s likely you’ll be asked by a client to design a HTML email. Before you rush to explain that all the cool kids are using social media, keep in mind that when done correctly, email is still one of the best ways to promote you and your clients online. In fact, a recent survey showed that every dollar spent on email marketing this year generated more than $40 in return. That’s more than any other marketing channel, including the cool ones.
There are a whole host of ingredients that contribute to a good email marketing campaign. Permission, relevance, timeliness and engaging content are all important. Even so, the biggest challenge for designers still remains building an email that renders well across all the popular email clients.
Same same, but different
Before getting into the details, there are some uncomfortable facts that those new to HTML email should be aware of. Building an email is not like building for the web. While web browsers continue their onward march towards standards, many email clients have stubbornly stayed put. Some have even gone backwards. In 2007, Microsoft switched the Outlook rendering engine from Internet Explorer to Word. Yes, as in the word processor. Add to this the quirks of the major web-based email clients like Gmail and Hotmail, sprinkle in a little Lotus Notes and you’ll soon realize how different the email game is.
While it’s not without its challenges, rest assured it can be done. In my experience the key is to focus on three things. First, you should keep it simple. The more complex your email design, the more likely is it to choke on one of the popular clients with poor standards support. Second, you need to take your coding skills back a good decade. That often means nesting tables, bringing CSS inline and following the coding guidelines I’ll outline below. Finally, you need to test your designs regularly. Just because a template looks nice in Hotmail now, doesn’t mean it will next week.
Setting your lowest common denominator
To maintain your sanity, it’s a good idea to decide exactly which email clients you plan on supporting when building a HTML email. While general research is helpful, the email clients your subscribers are using can vary significantly from list to list. If you have the time there are a number of tools that can tell you specifically which email clients your subscribers are using. Trust me, if the testing shows almost none of them are using a client like Lotus Notes, save yourself some frustration and ignore it altogether.
Knowing which email clients you’re targeting not only makes the building process easier, it can save you lots of time in the testing phase too. For the purpose of this article, I’ll be sharing techniques that give the best results across all of the popular clients, including the notorious ones like Gmail, Lotus Notes 6 and Outlook 2007. Just remember that pixel perfection in all email clients is a pipe dream.
Let’s get started.
Use tables for layout
Because clients like Gmail and Outlook 2007 have poor support for float, margin and padding, you’ll need to use tables as the framework of your email. While nested tables are widely supported, consistent treatment of width, margin and padding within table cells is not. For the best results, keep the following in mind when coding your table structure.
Set the width in each cell, not the table
When you combine table widths, td widths, td padding and CSS padding into an email, the final result is different in almost every email client. The most reliable way to set the width of your table is to set a width for each cell, not for the table itself.
<table cellspacing="0" cellpadding="10" border="0">
<tr>
<td width="80"></td>
<td width="280"></td>
</tr>
</table>
Never assume that if you don’t specify a cell width the email client will figure it out. It won’t. Also avoid using percentage based widths. Clients like Outlook 2007 don’t respect them, especially for nested tables. Stick to pixels. If you want to add padding to each cell, use either the cellpadding attribute of the table or CSS padding for each cell, but never combine the two.
Err toward nesting
Table nesting is far more reliable than setting left and right margins or padding for table cells. If you can achieve the same effect by table nesting, that will always give you the best result across the buggier email clients.
Use a container table for body background colors
Many email clients ignore background colors specified in your CSS or the <body> tag. To work around this, wrap your entire email with a 100% width table and give that a background color.
<table cellspacing="0" cellpadding="0" border="0" width="100%">
<tr>
<td bgcolor=”#000000”>
Your email code goes here.
</td>
</tr>
</table>
You can use the same approach for background images too. Just remember that some email clients don’t support them, so always provide a fallback color.
Avoid unnecessary whitespace in table cells
Where possible, avoid whitespace between your <td> tags. Some email clients (ahem, Yahoo! and Hotmail) can add additional padding above or below the cell contents in some scenarios, breaking your design for no apparent reason.
CSS and general font formatting
While some email designers do their best to avoid CSS altogether and rely on the dreaded <font> tag, the truth is many CSS properties are well supported by most email clients. See this comprehensive list of CSS support across the major clients for a good idea of the safe properties and those that should be avoided.
Always move your CSS inline
Gmail is the culprit for this one. By stripping the CSS from the <head> and <body> of any email, we’re left with no choice but to move all CSS inline. The good news is this is something you can almost completely automate. Free services like Premailer will move all CSS inline with the click of a button. I recommend leaving this step to the end of your build process so you can utilize all the benefits of CSS.
Avoid shorthand for fonts and hex notation
A number of email clients reject CSS shorthand for the font property. For example, never set your font styles like this.
p {
font:bold 1em/1.2em georgia,times,serif;
}
Instead, declare the properties individually like this.
p {
font-weight: bold;
font-size: 1em;
line-height: 1.2em;
font-family: georgia,times,serif;
}
While we’re on the topic of fonts, I recently tested every conceivable variation of @font-face across the major email clients. The results were dismal, so unfortunately it’s web-safe fonts in email for the foreseeable future.
When declaring the color property in your CSS, some email clients don’t support shorthand hexadecimal colors like color:#f60; instead of color:#ff6600;. Stick to the longhand approach for the best results.
Paragraphs
Just like table cell spacing, paragraph spacing can be tricky to get a consistent result across the board. I’ve seen many designers revert to using double <br /> or DIVs with inline CSS margins to work around these shortfalls, but recent testing showed that paragraph support is now reliable enough to use in most cases (there was a time when Yahoo! didn’t support the paragraph tag at all).
The best approach is to set the margin inline via CSS for every paragraph in your email, like so:
p {
margin: 0 0 1.6em 0;
}
Again, do this via CSS in the head when building your email, then use Premailer to bring it inline for each paragraph later.
If part of your design is height-sensitive and calls for pixel perfection, I recommend avoiding paragraphs altogether and setting the text formatting inline in the table cell. You might need to use table nesting or cellpadding / CSS to get the desired result. Here’s an example:
<td width="200" style="font-weight:bold; font-size:1em; line-height:1.2em; font-family:georgia,'times',serif;">your height sensitive text</td>
Links
Some email clients will overwrite your link colors with their defaults, and you can avoid this by taking two steps. First, set a default color for each link inline like so:
<a href="http://somesite.com/" style="color:#ff00ff">this is a link</a>
Next, add a redundant span inside the a tag.
<a href="http://somesite.com/" style="color:#ff00ff"><span style="color:#ff00ff">this is a link</span></a>
To some this may be overkill, but if link color is important to your design then a superfluous span is the best way to achieve consistency.
Images in HTML emails
The most important thing to remember about images in email is that they won’t be visible by default for many subscribers. If you start your design with that assumption, it forces you to keep things simple and ensure no important content is suppressed by image blocking.
With this in mind, here are the essentials to remember when using images in HTML email:
Avoid spacer images
While the combination of spacer images and nested tables was popular on the web ten years ago, image blocking in many email clients has ruled it out as a reliable technique today. Most clients replace images with an empty placeholder in the same dimensions, others strip the image altogether. Given image blocking is on by default in most email clients, this can lead to a poor first impression for many of your subscribers. Stick to fixed cell widths to keep your formatting in place with or without images.
Always include the dimensions of your image
If you forget to set the dimensions for each image, a number of clients will invent their own sizes when images are blocked and break your layout. Also, ensure that any images are correctly sized before adding them to your email. Some email clients will ignore the dimensions specified in code and rely on the true dimensions of your image.
Avoid PNGs
Lotus Notes 6 and 7 don’t support 8-bit or 24-bit PNG images, so stick with the GIF or JPG formats for all images, even if it means some additional file size.
Provide fallback colors for background images
Outlook 2007 has no support for background images (aside from this hack to get full page background images working). If you want to use a background image in your design, always provide a background color the email client can fall back on. This solves both the image blocking and Outlook 2007 problem simultaneously.
Don’t forget alt text
Lack of standards support means email clients have long destroyed the chances of a semantic and accessible HTML email. Even still, providing alt text is important from an image blocking perspective. Even with images suppressed by default, many email clients will display the provided alt text instead. Just remember that some email clients like Outlook 2007, Hotmail and Apple Mail don’t support alt text at all when images are blocked.
Use the display hack for Hotmail
For some inexplicable reason, Windows Live Hotmail adds a few pixels of additional padding below images. A workaround is to set the display property like so.
img {display:block;}
This removes the padding in Hotmail and still gives you the predicable result in other email clients.
Don’t use floats
Both Outlook 2007 and earlier versions of Notes offer no support for the float property. Instead, use the align attribute of the img tag to float images in your email.
<img src="image.jpg" align="right">
If you’re seeing strange image behavior in Yahoo! Mail, adding align=“top” to your images can often solve this problem.
Video in email
With no support for JavaScript or the object tag, video in email (if you can call it that) has long been limited to animated gifs. However, some recent research I did into the HTML5 video tag in email showed some promising results.
Turns out HTML5 video does work in many email clients right now, including Apple Mail, Entourage 2008, MobileMe and the iPhone. The real benefit of this approach is that if the video isn’t supported, you can provide reliable fallback content such as an animated GIF or a clickable image linking to the video in the browser.
Of course, the question of whether you should add video to email is another issue altogether. If you lean toward the “yes” side check out the technique with code samples.
What about mobile email?
The mobile email landscape was a huge mess until recently. With the advent of the iPhone, Android and big improvements from Palm and RIM, it’s becoming less important to think of mobile as a different email platform altogether.
That said, there are a few key pointers to keep in mind when coding your emails to get a decent result for your more mobile subscribers.
Keep the width less than 600 pixels
Because of email client preview panes, this rule was important long before mobile email clients came of age. In truth, the iPhone and Pre have a viewport of 320 pixels, the Droid 480 pixels and the Blackberry models hover around 360 pixels. Sticking to a maximum of 600 pixels wide ensures your design should still be readable when scaled down for each device. This width also gives good results in desktop and web-based preview panes.
Be aware of automatic text resizing
In what is almost always a good feature, email clients using webkit (such as the iPhone, Pre and Android) can automatically adjust font sizes to increase readability. If testing shows this feature is doing more harm than good to your design, you can always disable it with the following CSS rule:
-webkit-text-size-adjust: none;
Don’t forget to test
While standards support in email clients hasn’t made much progress in the last few years, there has been continual change (for better or worse) in some email clients. Web-based providers like Yahoo!, Hotmail and Gmail are notorious for this. On countless occasions I’ve seen a proven design suddenly stop working without explanation.
For this reason alone it’s important to retest your email designs on a regular basis. I find a quick test every month or so does the trick, especially in the web-based clients. The good news is that after designing and testing a few HTML email campaigns, you will find that order will emerge from the chaos. Many of these pitfalls will become quite predictable and your inbox-friendly designs will take shape with them in mind.
Looking ahead
Designing HTML email can be a tough pill for new designers and standardistas to swallow, especially given the fickle and retrospective nature of email clients today. With HTML5 just around the corner we are entering a new, uncertain phase. Will email client developers take the opportunity to repent on past mistakes and bring email clients into the present? The aim of groups such as the Email Standards Project is to make much of the above advice as redundant as the long-forgotten <blink> and <marquee> tags, however, only time will tell if this is to become a reality.
Although not the most compliant (or fashionable) medium, the results speak for themselves – email is, and will continue to be one of the most successful and targeted marketing channels available to you. As a designer with HTML email design skills in your arsenal, you have the opportunity to not only broaden your service offering, but gain a unique appreciation of how vital standards are.
Next steps
Ready to get started? There are a number of HTML email design galleries to provide ideas and inspiration for your own designs.
http://www.campaignmonitor.com/gallery/
http://htmlemailgallery.com/
http://inboxaward.com/
Enjoy! |
2009 |
David Greiner |
davidgreiner |
2009-12-13T00:00:00+00:00 |
https://24ways.org/2009/rock-solid-html-emails/ |
code |
| 263 |
Securing Your Site like It’s 1999 |
Running a website in the early years of the web was a scary business. The web was an evolving medium, and people were finding new uses for it almost every day. From book stores to online auctions, the web was an expanding universe of new possibilities.
As the web evolved, so too did the knowledge of its inherent security vulnerabilities. Clever tricks that were played on one site could be copied on literally hundreds of other sites. It was a normal sight to log in to a website to find nothing working because someone had breached its defences and deleted its database. Lessons in web security in those days were hard-earned.
What follows are examples of critical mistakes that brought down several early websites, and how you can help protect yourself and your team from the same fate.
Bad input validation: Trusting anything the user sends you
Our story begins in the most unlikely place: Animal Crossing. Animal Crossing was a 2001 video game set in a quaint town, filled with happy-go-lucky inhabitants that co-exist peacefully. Like most video games, Animal Crossing was the subject of many fan communities on the early web.
One such unofficial web forum was dedicated to players discussing their adventures in Animal Crossing. Players could trade secrets, ask for help, and share pictures of their virtual homes. This might sound like a model community to you, but you would be wrong.
One day, a player discovered a hidden field in the forum’s user profile form. Normally, this page allows users to change their name, their password, or their profile photo. This person discovered that the hidden field contained their unique user ID, which identifies them when the forum’s backend saves profile changes to its database. They discovered that by modifying the form to change the user ID, they could make changes to any other player’s profile.
Needless to say, this idyllic online community descended into chaos. Users changed each other’s passwords, deleted each other’s messages, and attacked each-other under the cover of complete anonymity. What happened?
There aren’t any official rules for developing software on the web. But if there were, my golden rule would be:
Never trust user input. Ever.
Always ask yourself how users will send you data that isn’t what it seems to be. If the nicest community of gamers playing the happiest game on earth can turn on each other, nowhere on the web is safe.
Make sure you validate user input to make sure it’s of the correct type (e.g. string, number, JSON string) and that it’s the length that you were expecting. Don’t forget that user input doesn’t become safe once it is stored in your database; any data that originates from outside your network can still be dangerous and must be escaped before it is inserted into HTML.
Make sure to check a user’s actions against what they are allowed to do. Create a clear access control policy that defines what actions a user may take, and to whose data they are allowed access to. For example, a newly-registered user should not be allowed to change the user profile of a web forum’s owner.
Finally, never rely on client-side validation. Validating user input in the browser is a convenience to the user, not a security measure. Always assume the user has full control over any data sent from the browser and make sure you validate any data sent to your backend from the outside world.
SQL injection: Allowing the user to run their own database queries
A long time ago, my favourite website was a web forum dedicated to the Final Fantasy video game series. Like the users of the Animal Crossing forum, I’d while away many hours arguing with other people on the internet about my favourite characters, my favourite stories, and the greatest controversies of the day.
One day, I noticed people were acting strangely. Users were being uncharacteristically nasty and posting in private areas of the forum they wouldn’t normally have access to. Then messages started disappearing, and user accounts for well-respected people were banned.
It turns out someone had discovered a way of logging in to any other user account, using a secret password that allowed them to do literally anything they wanted. What was this password that granted untold power to those who wielded it?
' OR '1'='1
SQL is a computer language that is used to query databases. When you fill out a login form, just like the one above, your username and your password are usually inserted into an SQL query like this:
SELECT COUNT(*)
FROM USERS
WHERE USERNAME='Alice'
AND PASSWORD='hunter2'
This query selects users from the database that match the username Alice and the password hunter2. If there is at least one user matching record, the user will be granted access. Let’s see what happens when we use our magic password instead!
SELECT COUNT(*)
FROM USERS
WHERE USERNAME='Admin'
AND PASSWORD='' OR '1'='1'
Does the password look like part of the query to you? That’s because it is! This password is a deliberate attempt to inject our own SQL into the query, hence the term SQL injection. The query is now looking for users matching the username Admin, with a password that is blank, or 1=1. In an SQL query, 1=1 is always true, which makes this query select every single record in the database. As long as the forum software is checking for at least one matching user, it will grant the person logging in access. This password will work for any user registered on the forum!
So how can you protect yourself from SQL injection?
Never build SQL queries by concatenating strings. Instead, use parameterised query tools. PHP offers prepared statements, and Node.JS has the knex package. Alternatively, you can use an ORM tool, such as Propel or sequelize.
Expert help in the form of language features or software tools is a key ally for securing your code. Get all the help you can!
Cross site request forgery: Getting other users to do your dirty work for you
Do you remember Netflix? Not the Netflix we have now, the Netflix that used to rent you DVDs by mailing them to you. My next story is about how someone managed to convince Netflix users to send him their DVDs - free of charge.
Have you ever clicked on a hyperlink, only to find something that you weren’t expecting? If you were lucky, you might have just gotten Rickrolled. If you were unlucky…
Let’s just say there are older and fouler things than Rick Astley in the dark places of the web.
What if you could convince people to visit a page you controlled? And what if those people were Netflix users, and they were logged in? In 2006, Dave Ferguson did just that. He created a harmless-looking page with an image on it:
<img src="http://www.netflix.com/JSON/AddToQueue?movieid=70110672" />
Did you notice the source URL of the image? It’s deliberately crafted to add a particular DVD to your queue. Sprinkle in a few more requests to change the user’s name and shipping address, and you could ship yourself DVDs completely free of charge!
This attack is possible when websites unconditionally trust a user’s session cookies without checking where HTTP requests come from.
The first check you can make is to verify that a request’s origin and referer headers match the location of the website. These headers can’t be programmatically set.
Another check you can use is to add CSRF tokens to your web forms, to verify requests have come from an actual form on your website. Tokens are long, unpredictable, unique strings that are generated by your server and inserted into web forms. When users complete a form, the form data sent to the server can be checked for a recently generated token. This is an effective deterrent of CSRF attacks because CSRF tokens aren’t stored in cookies.
You can also set SameSite=Strict when setting cookies with the Set-Cookie HTTP header. This communicates to browsers that cookies are not to be sent with cross-site requests. This is a relatively new feature, though it is well supported in evergreen browsers.
Cross site scripting: Someone else’s code running on your website
In 2005, Samy Kamkar became famous for having lots of friends. Lots and lots of friends.
Samy enjoyed using MySpace which, at the time, was the world’s largest social network. Social networks at that time were more limited than today. For instance, MySpace let you upload photos to your photo gallery, but capped the limit at twelve. Twelve photos. At least you didn’t have to wade through photos of avocado toast back then…
Samy discovered that MySpace also locked down the kinds of content that you could post on your MySpace page. He discovered he could inject <img /> and <div /> tags into his headline, but <script /> was filtered. MySpace wasn’t about to let someone else run their own code on MySpace.
Intrigued, Samy set about finding out exactly what he could do with <img /> and <div /> tags. He found that you could add style properties to <div /> tags to style them with CSS.
<div style="background:url('javascript:alert(1)')">
This code only worked in Internet Explorer and in some versions of Safari, but that was plenty of people to befriend. However, MySpace was prepared for this: they also filtered the word javascript from <div />.
<div style="background:url('java
script:alert(1)')">
Samy discovered that by inserting a line break into his code, MySpace would not filter out the word javascript. The browser would continue to run the code just fine! Samy had now broken past MySpace’s first line of defence and was able to start running code on his profile page. Now he started looking at what he could do with that code.
alert(document.body.innerHTML)
Samy wondered if he could inspect the page’s source to find the details of other MySpace users to befriend. To do this, you would normally use document.body.innerHTML, but MySpace had filtered this too.
alert(eval('document.body.inne' + 'rHTML'))
This isn’t a problem if you build up JavaScript code inside a string and execute it using the eval() function. This trick also worked with XMLHttpRequest.onReadyStateChange, which allowed Samy to send friend requests to the MySpace API and install the JavaScript code on his new friends’ pages.
One final obstacle stood in his way. The same origin policy is a security mechanism that prevents scripts hosted on one domain interacting with sites hosted on another domain.
if (location.hostname == 'profile.myspace.com') {
document.location = 'http://www.myspace.com'
+ location.pathname + location.search
}
Samy discovered that only the http://www.myspace.com domain would accept his API requests, and requests from http://profile.myspace.com were being blocked by the browser’s same-origin policy. By redirecting the browser to http://www.myspace.com, he discovered that he could load profile pages and successfully make requests to MySpace’s API. Samy installed this code on his profile page, and he waited.
Over the course of the next day, over a million people unwittingly installed Samy’s code into their MySpace profile pages and invited their friends. The load of friend requests on MySpace was so large that the site buckled and shut down. It took them two hours to remove Samy’s code and patch the security holes he exploited. Samy was raided by the United States secret service and sentenced to do 90 days of community service.
This is the power of installing a little bit of JavaScript on someone else’s website. It is called cross site scripting, and its effects can be devastating. It is suspected that cross-site scripting was to blame for the 2018 British Airways breach that leaked the credit card details of 380,000 people.
So how can you help protect yourself from cross-site scripting?
Always sanitise user input when it comes in, using a library such as sanitize-html. Open source tools like this benefit from hundreds of hours of work from dozens of experienced contributors. Don’t be tempted to roll your own protection. MySpace was prepared, but they were not prepared enough. It makes no sense to turn this kind of help down.
You can also use an auto-escaping templating language to make sure nobody else’s HTML can get into your pages. Both Angular and React will do this for you, and they are extremely convenient to use.
You should also implement a content security policy to restrict the domains that content like scripts and stylesheets can be loaded from. Loading content from sites not under your control is a significant security risk, and you should use a CSP to lock this down to only the sources you trust. CSP can also block the use of the eval() function.
For content not under your control, consider setting up sub-resource integrity protection. This allows you to add hashes to stylesheets and scripts you include on your website. Hashes are like fingerprints for digital files; if the content changes, so does the fingerprint. Adding hashes will allow your browser to keep your site safe if the content changes without you knowing.
npm audit: Protecting yourself from code you don’t own
JavaScript and npm run the modern web. Together, they make it easy to take advantage of the world’s largest public registry of open source software. How do you protect yourself from code written by someone you’ve never met? Enter npm audit.
npm audit reviews the security of your website’s dependency tree. You can start using it by upgrading to the latest version of npm:
npm install npm -g
npm audit
When you run npm audit, npm submits a description of your dependencies to the Registry, which returns a report of known vulnerabilities for the packages you have installed.
If your website has a known cross-site scripting vulnerability, npm audit will tell you about it. What’s more, if the vulnerability has been patched, running npm audit fix will automatically install the patched package for you!
Securing your site like it’s 2019
The truth is that since the early days of the web, the stakes of a security breach have become much, much higher. The web is so much more than fandom and mailing DVDs - online banking is now mainstream, social media and dating websites store intimate information about our personal lives, and we are even inviting the internet into our homes.
However, we have powerful new allies helping us stay safe. There are more resources than ever before to teach us how to write secure code. Tools like Angular and React are designed with security features baked-in from the start. We have a new generation of security tools like npm audit to watch over our dependencies.
As we roll over into 2019, let’s take the opportunity to reflect on the security of the code we write and be grateful for the everything we’ve learned in the last twenty years. |
2018 |
Katie Fenn |
katiefenn |
2018-12-01T00:00:00+00:00 |
https://24ways.org/2018/securing-your-site-like-its-1999/ |
code |
| 104 |
Sitewide Search On A Shoe String |
One of the questions I got a lot when I was building web sites for smaller businesses was if I could create a search engine for their site. Visitors should be able to search only this site and find things without the maintainer having to put “related articles” or “featured content” links on every page by hand.
Back when this was all fields this wasn’t easy as you either had to write your own scraping tool, use ht://dig or a paid service from providers like Yahoo, Altavista or later on Google. In the former case you had to swallow the bitter pill of computing and indexing all your content and storing it in a database for quick access and in the latter it hurt your wallet.
Times have moved on and nowadays you can have the same functionality for free using Yahoo’s “Build your own search service” – BOSS. The cool thing about BOSS is that it allows for a massive amount of hits a day and you can mash up the returned data in any format you want. Another good feature of it is that it comes with JSON-P as an output format which makes it possible to use it without any server-side component!
Starting with a working HTML form
In order to add a search to your site, you start with a simple HTML form which you can use without JavaScript. Most search engines will allow you to filter results by domain. In this case we will search “bbc.co.uk”. If you use Yahoo as your standard search, this could be:
<form id="customsearch" action="http://search.yahoo.com/search">
<div>
<label for="p">Search this site:</label>
<input type="text" name="p" id="term">
<input type="hidden" name="vs" id="site" value="bbc.co.uk">
<input type="submit" value="go">
</div>
</form>
The Google equivalent is:
<form id="customsearch" action="http://www.google.co.uk/search">
<div>
<label for="p">Search this site:</label>
<input type="text" name="as_q" id="term">
<input type="hidden" name="as_sitesearch" id="site" value="bbc.co.uk">
<input type="submit" value="go">
</div>
</form>
In any case make sure to use the ID term for the search term and site for the site, as this is what we are going to use for the script. To make things easier, also have an ID called customsearch on the form.
To use BOSS, you should get your own developer API for BOSS and replace the one in the demo code. There is click tracking on the search results to see how successful your app is, so you should make it your own.
Adding the BOSS magic
BOSS is a REST API, meaning you can use it in any HTTP request or in a browser by simply adding the right parameters to a URL. Say for example you want to search “bbc.co.uk” for “christmas” all you need to do is open the following URL:
http://boss.yahooapis.com/ysearch/web/v1/christmas?sites=bbc.co.uk&format=xml&appid=YOUR-APPLICATION-ID
Try it out and click it to see the results in XML. We don’t want XML though, which is why we get rid of the format=xml parameter which gives us the same information in JSON:
http://boss.yahooapis.com/ysearch/web/v1/christmas?sites=bbc.co.uk&appid=YOUR-APPLICATION-ID
JSON makes most sense when you can send the output to a function and immediately use it. For this to happen all you need is to add a callback parameter and the JSON will be wrapped in a function call. Say for example we want to call SITESEARCH.found() when the data was retrieved we can do it this way:
http://boss.yahooapis.com/ysearch/web/v1/christmas?sites=bbc.co.uk&callback=SITESEARCH.found&appid=YOUR-APPLICATION-ID
You can use this immediately in a script node if you want to. The following code would display the total amount of search results for the term christmas on bbc.co.uk as an alert:
<script type="text/javascript">
var SITESEARCH = {};
SITESEARCH.found = function(o){
alert(o.ysearchresponse.totalhits);
}
</script>
<script type="text/javascript" src="http://boss.yahooapis.com/ysearch/web/v1/christmas?sites=bbc.co.uk&callback=SITESEARCH.found&appid=Kzv_lcHV34HIybw0GjVkQNnw4AEXeyJ9Rb1gCZSGxSRNrcif_HdMT9qTE1y9LdI-">
</script>
However, for our example, we need to be a bit more clever with this.
Enhancing the search form
Here’s the script that enhances a search form to show results below it.
SITESEARCH = function(){
var config = {
IDs:{
searchForm:'customsearch',
term:'term',
site:'site'
},
loading:'Loading results...',
noresults:'No results found.',
appID:'YOUR-APP-ID',
results:20
};
var form;
var out;
function init(){
if(config.appID === 'YOUR-APP-ID'){
alert('Please get a real application ID!');
} else {
form = document.getElementById(config.IDs.searchForm);
if(form){
form.onsubmit = function(){
var site = document.getElementById(config.IDs.site).value;
var term = document.getElementById(config.IDs.term).value;
if(typeof site === 'string' && typeof term === 'string'){
if(typeof out !== 'undefined'){
out.parentNode.removeChild(out);
}
out = document.createElement('p');
out.appendChild(document.createTextNode(config.loading));
form.appendChild(out);
var APIurl = 'http://boss.yahooapis.com/ysearch/web/v1/' +
term + '?callback=SITESEARCH.found&sites=' +
site + '&count=' + config.results +
'&appid=' + config.appID;
var s = document.createElement('script');
s.setAttribute('src',APIurl);
s.setAttribute('type','text/javascript');
document.getElementsByTagName('head')[0].appendChild(s);
return false;
}
};
}
}
};
function found(o){
var list = document.createElement('ul');
var results = o.ysearchresponse.resultset_web;
if(results){
var item,link,description;
for(var i=0,j=results.length;i<j;i++){
item = document.createElement('li');
link = document.createElement('a');
link.setAttribute('href',results[i].clickurl);
link.innerHTML = results[i].title;
item.appendChild(link);
description = document.createElement('p');
description.innerHTML = results[i]['abstract'];
item.appendChild(description);
list.appendChild(item);
}
} else {
list = document.createElement('p');
list.appendChild(document.createTextNode(config.noresults));
}
form.replaceChild(list,out);
out = list;
};
return{
config:config,
init:init,
found:found
};
}();
Oooohhhh scary code! Let’s go through this one bit at a time:
We start by creating a module called SITESEARCH and give it an configuration object:
SITESEARCH = function(){
var config = {
IDs:{
searchForm:'customsearch',
term:'term',
site:'site'
},
loading:'Loading results...',
appID:'YOUR-APP-ID',
results:20
}
Configuration objects are a great idea to make your code easy to change and also to override. In this case you can define different IDs than the one agreed upon earlier, define a message to show when the results are loading, when there aren’t any results, the application ID and the number of results that should be displayed.
Note: you need to replace “YOUR-APP-ID” with the real ID you retrieved from BOSS, otherwise the script will complain!
var form;
var out;
function init(){
if(config.appID === 'YOUR-APP-ID'){
alert('Please get a real application ID!');
} else {
We define form and out as variables to make sure that all the methods in the module have access to them. We then check if there was a real application ID defined. If there wasn’t, the script complains and that’s that.
form = document.getElementById(config.IDs.searchForm);
if(form){
form.onsubmit = function(){
var site = document.getElementById(config.IDs.site).value;
var term = document.getElementById(config.IDs.term).value;
if(typeof site === 'string' && typeof term === 'string'){
If the application ID was a winner, we check if the form with the provided ID exists and apply an onsubmit event handler. The first thing we get is the values of the site we want to search in and the term that was entered and check that those are strings.
if(typeof out !== 'undefined'){
out.parentNode.removeChild(out);
}
out = document.createElement('p');
out.appendChild(document.createTextNode(config.loading));
form.appendChild(out);
If both are strings we check of out is undefined. We will create a loading message and subsequently the list of search results later on and store them in this variable. So if out is defined, it’ll be an old version of a search (as users will re-submit the form over and over again) and we need to remove that old version.
We then create a paragraph with the loading message and append it to the form.
var APIurl = 'http://boss.yahooapis.com/ysearch/web/v1/' +
term + '?callback=SITESEARCH.found&sites=' +
site + '&count=' + config.results +
'&appid=' + config.appID;
var s = document.createElement('script');
s.setAttribute('src',APIurl);
s.setAttribute('type','text/javascript');
document.getElementsByTagName('head')[0].appendChild(s);
return false;
}
};
}
}
};
Now it is time to call the BOSS API by assembling a correct REST URL, create a script node and apply it to the head of the document. We return false to ensure the form does not get submitted as we want to stay on the page.
Notice that we are using SITESEARCH.found as the callback method, which means that we need to define this one to deal with the data returned by the API.
function found(o){
var list = document.createElement('ul');
var results = o.ysearchresponse.resultset_web;
if(results){
var item,link,description;
We create a new list and then get the resultset_web array from the data returned from the API. If there aren’t any results returned, this array will not exist which is why we need to check for it. Once we done that we can define three variables to repeatedly store the item title we want to display, the link to point to and the description of the link.
for(var i=0,j=results.length;i<j;i++){
item = document.createElement('li');
link = document.createElement('a');
link.setAttribute('href',results[i].clickurl);
link.innerHTML = results[i].title;
item.appendChild(link);
description = document.createElement('p');
description.innerHTML = results[i]['abstract'];
item.appendChild(description);
list.appendChild(item);
}
We then loop over the results array and assemble a list of results with the titles in links and paragraphs with the abstract of the site. Notice the bracket notation for abstract as abstract is a reserved word in JavaScript2 :).
} else {
list = document.createElement('p');
list.appendChild(document.createTextNode(config.noresults));
}
form.replaceChild(list,out);
out = list;
};
If there aren’t any results, we define a paragraph with the no results message as list. In any case we replace the old out (the loading message) with the list and re-define out as the list.
return{
config:config,
init:init,
found:found
};
}();
All that is left to do is return the properties and methods we want to make public. In this case found needs to be public as it is accessed by the API return. We return init to make it accessible and config to allow implementers to override any of the properties.
Using the script
In order to use this script, all you need to do is to add it after the form in the document, override the API key with your own and call init():
<form id="customsearch" action="http://search.yahoo.com/search">
<div>
<label for="p">Search this site:</label>
<input type="text" name="p" id="term">
<input type="hidden" name="vs" id="site" value="bbc.co.uk">
<input type="submit" value="go">
</div>
</form>
<script type="text/javascript" src="boss-site-search.js"></script>
<script type="text/javascript">
SITESEARCH.config.appID = 'copy-the-id-you-know-to-get-where';
SITESEARCH.init();
</script>
Where to go from here
This is just a very simple example of what you can do with BOSS. You can define languages and regions, retrieve and display images and news and mix the results with other data sources before displaying them. One very cool feature is that by adding a view=keyterms parameter to the URL you can get the keywords of each of the results to drill deeper into the search. An example for this written in PHP is available on the YDN blog. For JavaScript solutions there is a handy wrapper called yboss available to help you go nuts. |
2008 |
Christian Heilmann |
chrisheilmann |
2008-12-04T00:00:00+00:00 |
https://24ways.org/2008/sitewide-search-on-a-shoestring/ |
code |
| 300 |
Taking Device Orientation for a Spin |
When The Police sang “Don’t Stand So Close To Me” they weren’t talking about using a smartphone to view a panoramic image on Facebook, but they could have been. For years, technology has driven relentlessly towards devices we can carry around in our pockets, and now that we’re there, we’re expected to take the thing out of our pocket and wave it around in front of our faces like a psychotic donkey in search of its own dangly carrot.
But if you can’t beat them, join them.
A brave new world
A couple of years back all sorts of specs for new HTML5 APIs sprang up much to our collective glee. Emboldened, we ran a few tests and found they basically didn’t work in anything and went off disheartened into the corner for a bit of a sob.
Turns out, while we were all busy boohooing, those browser boffins have actually being doing some work, and lo and behold, some of these APIs are even half usable. Mostly literally half usable—we’re still talking about browsers, after all.
Now, of course they’re all a bit JavaScripty and are going to involve complex methods and maths and science and probably about a thousand dependancies from Github that will fall out of fashion while we’re still trying to locate the documentation, right? Well, no!
So what if we actually wanted to use one of these APIs, say to impress our friends with our ability to make them wave their phones in front of their faces (because no one enjoys looking hapless more than the easily-technologically-impressed), how could we do something like that? Let’s find out.
The Device Orientation API
The phone-wavy API is more formally known as the DeviceOrientation Event Specification. It does a bunch of stuff that basically doesn’t work, but also gives us three values that represent orientation of a device (a phone, a tablet, probably not a desktop computer) around its x, y and z axes. You might think of it as pitch, roll and yaw if you like to spend your weekends wearing goggles and a leather hat.
The main way we access these values is through an event listener, which can inform our code every time the value changes. Which is constantly, because you try and hold a phone still and then try and hold the Earth still too.
The API calls those pitch, roll and yaw values alpha, beta and gamma. Chocks away:
window.addEventListener('deviceorientation', function(e) {
console.log(e.alpha);
console.log(e.beta);
console.log(e.gamma);
});
If you look at this test page on your phone, you should be able to see the numbers change as you twirl the thing around your body like the dance partner you never had. Wrist strap recommended.
One important note
Like may of these newfangled APIs, Device Orientation is only available over HTTPS. We’re not allowed to have too much fun without protection, so make sure that you’re working on a secure line. I’ve found a quick and easy way to share my local dev environment over TLS with my devices is to use an ngrok tunnel.
ngrok http -host-header=rewrite mylocaldevsite.dev:80
ngrok will then set up a tunnel to your dev site with both HTTP and HTTPS URL options. You, of course, want the HTTPS option.
Right, where were we?
Make something to look at
It’s all well and good having a bunch of numbers, but they’re no use unless we do something with them. Something creative. Something to inspire the generations. Or we could just build that Facebook panoramic image viewer thing (because most of us are familiar with it and we’re not trying to be too clever here). Yeah, let’s just build one of those.
Our basic framework is going to be similar to that used for an image carousel. We have a container, constrained in size, and CSS overflow property set to hidden. Into this we place our wide content and use positioning to move the content back and forth behind the ‘window’ so that the part we want to show is visible.
Here it is mocked up with a slider to set the position. When you release the slider, the position updates. (This actually tests best on desktop with your window slightly narrowed.)
The details of the slider aren’t important (we’re about to replace it with phone-wavy goodness) but the crucial part is that moving the slider results in a function call to position the image. This takes a percentage value (0-100) with 0 being far left and 100 being far right (or ‘alt-nazi’ or whatever).
var position_image = function(percent) {
var pos = (img_W / 100)*percent;
img.style.transform = 'translate(-'+pos+'px)';
};
All this does is figure out what that percentage means in terms of the image width, and set the transform: translate(…); CSS property to move the image. (We use translate because it might be a bit faster to animate than left/right positioning.)
Ok. We can now read the orientation values from our device, and we can programatically position the image. What we need to do is figure out how to convert those raw orientation values into a nice tidy percentage to pass to our function and we’re done. (We’re so not done.)
The maths bit
If we go back to our raw values test page and make-believe that we have a fascinating panoramic image of some far-off beach or historic monument to look at, you’ll note that the main value that is changing as we swing back and forth is the ‘alpha’ value. That’s the one we want to track.
As our goal here is hey, these APIs are interesting and fun and not let’s build the world’s best panoramic image viewer, we’ll start by making a few assumptions and simplifications:
When the image loads, we’ll centre the image and take the current nose-forward orientation reading as the middle.
Moving left, we’ll track to the left of the image (lower percentage).
Moving right, we’ll track to the right (higher percentage).
If the user spins round, does cartwheels or loads the page then hops on a plane and switches earthly hemispheres, they’re on their own.
Nose-forward
When the page loads, the initial value of alpha gives us our nose-forward position. In Safari on iOS, this is normalised to always be 0, whereas most everywhere else it tends to be bound to pointy-uppy north. That doesn’t really matter to us, as we don’t know which direction the user might be facing in anyway — we just need to record that initial state and then use it to compare any new readings.
var initial_position = null;
window.addEventListener('deviceorientation', function(e) {
if (initial_position === null) {
initial_position = Math.floor(e.alpha);
};
var current_position = initial_position - Math.floor(e.alpha);
});
(I’m rounding down the values with Math.floor() to make debugging easier - we’ll take out the rounding later.)
We get our initial position if it’s not yet been set, and then calculate the current position as a difference between the new value and the stored one.
These values are weird
One thing you need to know about these values, is that they range from 0 to 360 but then you also get weird left-of-zero values like -2 and whatever. And they wrap past 360 back to zero as you’d expect if you do a forward roll.
What I’m interested in is working out my rotation. If 0 is my nose-forward position, I want a positive value as I turn right, and a negative value as I turn left. That puts the awkward 360-tipping point right behind the user where they can’t see it.
var rotation = current_position;
if (current_position > 180) rotation = current_position-360;
Which way up?
Since we’re talking about orientation, we need to remember that the values are going to be different if the device is held in portrait on landscape mode. See for yourself - wiggle it like a steering wheel and you get different values. That’s easy to account for when you know which way up the device is, but in true browser style, the API for that bit isn’t well supported. The best I can come up with is:
var screen_portrait = false;
if (window.innerWidth < window.innerHeight) {
screen_portrait = true;
}
It works. Then we can use screen_portrait to branch our code:
if (screen_portrait) {
if (current_position > 180) rotation = current_position-360;
} else {
if (current_position < -180) rotation = 360+current_position;
}
Here’s the code in action so you can see the values for yourself. If you change screen orientation you’ll need to refresh the page (it’s a demo!).
Limiting rotation
Now, while the youth of today are rarely seen without a phone in their hands, it would still be unreasonable to ask them to spin through 360° to view a photo. Instead, we need to limit the range of movement to something like 60°-from-nose in either direction and normalise our values to pan the entire image across that 120° range. -60 would be full-left (0%) and 60 would be full-right (100%).
If we set max_rotation = 60, that code ends up looking like this:
if (rotation > max_rotation) rotation = max_rotation;
if (rotation < (0-max_rotation)) rotation = 0-max_rotation;
var percent = Math.floor(((rotation + max_rotation)/(max_rotation*2))*100);
We should now be able to get a rotation from -60° to +60° expressed as a percentage. Try it for yourself.
The big reveal
All that’s left to do is pass that percentage to our image positioning function and would you believe it, it might actually work.
position_image(percent);
You can see the final result and take it for a spin. Literally.
So what have we made here? Have we built some highly technical panoramic image viewer to aid surgeons during life-saving operations using only JavaScript and some slightly questionable mathematics? No, my friends, we have not. Far from it.
What we have made is progress. We’ve taken a relatively newly available hardware API and a bit of simple JavaScript and paired it with existing CSS knowledge and made something that we didn’t have this morning. Something we probably didn’t even want this morning. Something that if you take a couple of steps back and squint a bit might be a prototype for something vaguely interesting. But more importantly, we’ve learned that our browsers are just a little bit more capable than we thought.
The web platform is maturing rapidly. There are new, relatively unexplored APIs for doing all sorts of crazy thing that are often dismissed as the preserve of native apps. Like some sort of app marmalade. Poppycock.
The web is an amazing, exciting place to create things. All it takes is some base knowledge of the fundamentals, a creative mind and a willingness to learn. We have those! So let’s create things. |
2016 |
Drew McLellan |
drewmclellan |
2016-12-24T00:00:00+00:00 |
https://24ways.org/2016/taking-device-orientation-for-a-spin/ |
code |
| 132 |
Tasty Text Trimmer |
In most cases, when designing a user interface it’s best to make a decision about how data is best displayed and stick with it. Failing to make a decision ultimately leads to too many user options, which in turn can be taxing on the poor old user.
Under some circumstances, however, it’s good to give the user freedom in customising their workspace. One good example of this is the ‘Article Length’ tool in Apple’s Safari RSS reader. Sliding a slider left of right dynamically changes the length of each article shown. It’s that kind of awesomey magic stuff that’s enough to keep you from sleeping. Let’s build one.
The Setup
Let’s take a page that has lots of long text items, a bit like a news page or like Safari’s RSS items view. If we were to attach a class name to each element we wanted to resize, that would give us something to hook onto from the JavaScript.
Example 1: The basic page.
As you can see, I’ve wrapped my items in a DIV and added a class name of chunk to them. It’s these chunks that we’ll be finding with the JavaScript. Speaking of which …
Our Core Functions
There are two main tasks that need performing in our script. The first is to find the chunks we’re going to be resizing and store their original contents away somewhere safe. We’ll need this so that if we trim the text down we’ll know what it was if the user decides they want it back again. We’ll call this loadChunks.
var loadChunks = function(){
var everything = document.getElementsByTagName('*');
var i, l;
chunks = [];
for (i=0, l=everything.length; i<l; i++){
if (everything[i].className.indexOf(chunkClass) > -1){
chunks.push({
ref: everything[i],
original: everything[i].innerHTML
});
}
}
};
The variable chunks is stored outside of this function so that we can access it from our next core function, which is doTrim.
var doTrim = function(interval) {
if (!chunks) loadChunks();
var i, l;
for (i=0, l=chunks.length; i<l; i++){
var a = chunks[i].original.split(' ');
a = a.slice(0, interval);
chunks[i].ref.innerHTML = a.join(' ');
}
};
The first thing that needs to be done is to call loadChunks if the chunks variable isn’t set. This should only happen the first time doTrim is called, as from that point the chunks will be loaded.
Then all we do is loop through the chunks and trim them. The trimming itself (lines 6-8) is very simple. We split the text into an array of words (line 6), then select only a portion from the beginning of the array up until the number we want (line 7). Finally the words are glued back together (line 8).
In essense, that’s it, but it leaves us needing to know how to get the number into this function in the first place, and how that number is generated by the user. Let’s look at the latter case first.
The YUI Slider Widget
There are lots of JavaScript libraries available at the moment. A fair few of those are really good. I use the Yahoo! User Interface Library professionally, but have only recently played with their pre-build slider widget. Turns out, it’s pretty good and perfect for this task.
Once you have the library files linked in (check the docs linked above) it’s fairly straightforward to create yourself a slider.
slider = YAHOO.widget.Slider.getHorizSlider("sliderbg", "sliderthumb", 0, 100, 5);
slider.setValue(50);
slider.subscribe("change", doTrim);
All that’s needed then is some CSS to make the slider look like a slider, and of course a few bits of HTML. We’ll see those later.
See It Working!
Rather than spell out all the nuts and bolts of implementing this fairly simple script, let’s just look at in it action and then pick on some interesting bits I’ve added.
Example 2: Try the Tasty Text Trimmer.
At the top of the JavaScript file I’ve added a small number of settings.
var chunkClass = 'chunk';
var minValue = 10;
var maxValue = 100;
var multiplier = 5;
Obvious candidates for configuration are the class name used to find the chunks, and also the some minimum and maximum values. The minValue is the fewest number of words we wish to display when the slider is all the way down. The maxValue is the length of the slider, in this case 100.
Moving the slider makes a call to our doTrim function with the current value of the slider. For a slider 100 pixels long, this is going to be in the range of 0-100. That might be okay for some things, but for longer items of text you’ll want to allow for displaying more than 100 words. I’ve accounted for this by adding in a multiplier – in my code I’m multiplying the value by 5, so a slider value of 50 shows 250 words. You’ll probably want to tailor the multiplier to the type of content you’re using.
Keeping it Accessible
This effect isn’t something we can really achieve without JavaScript, but even so we must make sure that this functionality has no adverse impact on the page when JavaScript isn’t available. This is achieved by adding the slider markup to the page from within the insertSliderHTML function.
var insertSliderHTML = function(){
var s = '<a id="slider-less" href="#less"><img src="icon_min.gif" width="10" height="10" alt="Less text" class="first" /></a>';
s +=' <div id="sliderbg"><div id="sliderthumb"><img src="sliderthumbimg.gif" /></div></div>';
s +=' <a id="slider-more" href="#more"><img src="icon_max.gif" width="10" height="10" alt="More text" /></a>';
document.getElementById('slider').innerHTML = s;
}
The other important factor to consider is that a slider can be tricky to use unless you have good eyesight and pretty well controlled motor skills. Therefore we should provide a method of changing the value by the keyboard.
I’ve done this by making the icons at either end of the slider links so they can be tabbed to. Clicking on either icon fires the appropriate JavaScript function to show more or less of the text.
In Conclusion
The upshot of all this is that without JavaScript the page just shows all the text as it normally would. With JavaScript we have a slider for trimming the text excepts that can be controlled with the mouse or with a keyboard.
If you’re like me and have just scrolled to the bottom to find the working demo, here it is again:
Try the Tasty Text Trimmer
Trimmer for Christmas? Don’t say I never give you anything! |
2006 |
Drew McLellan |
drewmclellan |
2006-12-01T00:00:00+00:00 |
https://24ways.org/2006/tasty-text-trimmer/ |
code |
| 65 |
The Accessibility Mindset |
Accessibility is often characterized as additional work, hard to learn and only affecting a small number of people. Those myths have no logical foundation and often stem from outdated information or misconceptions.
Indeed, it is an additional skill set to acquire, quite like learning new JavaScript frameworks, CSS layout techniques or new HTML elements. But it isn’t particularly harder to learn than those other skills.
A World Health Organization (WHO) report on disabilities states that,
[i]ncluding children, over a billion people (or about 15% of the world’s population) were estimated to be living with disability.
Being disabled is not as unusual as one might think. Due to chronic health conditions and older people having a higher risk of disability, we are also currently paving the cowpath to an internet that we can still use in the future.
Accessibility has a very close relationship with usability, and advancements in accessibility often yield improvements in the usability of a website. Websites are also more adaptable to users’ needs when they are built in an accessible fashion.
Beyond the bare minimum
In the time of table layouts, web developers could create code that passed validation rules but didn’t adhere to the underlying semantic HTML model. We later developed best practices, like using lists for navigation, and with HTML5 we started to wrap those lists in nav elements. Working with accessibility standards is similar. The Web Content Accessibility Guidelines (WCAG) 2.0 can inform your decision to make websites accessible and can be used to test that you met the success criteria. What it can’t do is measure how well you met them.
W3C developed a long list of techniques that can be used to make your website accessible, but you might find yourself in a situation where you need to adapt those techniques to be the most usable solution for your particular problem.
The checkbox below is implemented in an accessible way: The input element has an id and the label associated with the checkbox refers to the input using the for attribute. The hover area is shown with a yellow background and a black dotted border:
Open video
The label is clickable and the checkbox has an accessible description. Job done, right? Not really. Take a look at the space between the label and the checkbox:
Open video
The gutter is created using a right margin which pushes the label to the right. Users would certainly expect this space to be clickable as well. The simple solution is to wrap the label around the checkbox and the text:
Open video
You can also set the label to display:block; to further increase the clickable area:
Open video
And while we’re at it, users might expect the whole box to be clickable anyway. Let’s apply the CSS that was on a wrapping div element to the label directly:
Open video
The result enhances the usability of your form element tremendously for people with lower dexterity, using a voice mouse, or using touch interfaces. And we only used basic HTML and CSS techniques; no JavaScript was added and not one extra line of CSS.
<form action="#">
<label for="uniquecheckboxid">
<input type="checkbox" name="checkbox" id="uniquecheckboxid" />
Checkbox 4
</label>
</form>
Button Example
The button below looks like a typical edit button: a pencil icon on a real button element. But if you are using a screen reader or a braille keyboard, the button is just read as “button” without any indication of what this button is for.
Open video
A screen reader announcing a button. Contains audio.
The code snippet shows why the button is not properly announced:
<button>
<span class="icon icon-pencil"></span>
</button>
An icon font is used to display the icon and no text alternative is given. A possible solution to this problem is to use the title or aria-label attributes, which solves the alternative text use case for screen reader users:
Open video
A screen reader announcing a button with a title.
However, screen readers are not the only way people with and without disabilities interact with websites. For example, users can reset or change font families and sizes at will. This helps many users make websites easier to read, including people with dyslexia. Your icon font might be replaced by a font that doesn’t include the glyphs that are icons. Additionally, the icon font may not load for users on slow connections, like on mobile phones inside trains, or because users decided to block external fonts altogether. The following screenshots show the mobile GitHub view with and without external fonts:
The mobile GitHub view with and without external fonts.
Even if the title/aria-label approach was used, the lack of visual labels is a barrier for most people under those circumstances. One way to tackle this is using the old-fashioned img element with an appropriate alt attribute, but surprisingly not every browser displays the alternative text visually when the image doesn’t load.
<button>
<img src="icon-pencil.svg" alt="Edit">
</button>
Providing always visible text is an alternative that can work well if you have the space. It also helps users understand the meaning of the icons.
<button>
<span class="icon icon-pencil"></span> Edit
</button>
This also reads just fine in screen readers:
Open video
A screen reader announcing the revised button.
Clever usability enhancements don’t stop at a technical implementation level. Take the BBC iPlayer pages as an example: when a user navigates the “captioned videos” or “audio description” categories and clicks on one of the videos, captions or audio descriptions are automatically switched on. Small things like this enhance the usability and don’t need a lot of engineering resources. It is more about connecting the usability dots for people with disabilities. Read more about the BBC iPlayer accessibility case study.
More information
W3C has created several documents that make it easier to get the gist of what web accessibility is and how it can benefit everyone. You can find out “How People with Disabilities Use the Web”, there are “Tips for Getting Started” for developers, designers and content writers. And for the more seasoned developer there is a set of tutorials on web accessibility, including information on crafting accessible forms and how to use images in an accessible way.
Conclusion
You can only produce a web project with long-lasting accessibility if accessibility is not an afterthought. Your organization, your division, your team need to think about accessibility as something that is the foundation of your website or project. It needs to be at the same level as performance, code quality and design, and it needs the same attention. Users often don’t notice when those fundamental aspects of good website design and development are done right. But they’ll always know when they are implemented poorly.
If you take all this into consideration, you can create accessibility solutions based on the available data and bring accessibility to people who didn’t know they’d need it:
Open video
In this video from the latest Apple keynote, the Apple TV is operated by voice input through a remote. When the user asks “What did she say?” the video jumps back fifteen seconds and captions are switched on for a brief time. All three, the remote, voice input and captions have their roots in assisting people with disabilities. Now they benefit everyone. |
2015 |
Eric Eggert |
ericeggert |
2015-12-17T00:00:00+00:00 |
https://24ways.org/2015/the-accessibility-mindset/ |
code |
| 260 |
The Art of Mathematics: A Mandala Maker Tutorial |
In front-end development, there’s often a great deal of focus on tools that aim to make our work more efficient. But what if you’re new to web development? When you’re just starting out, the amount of new material can be overwhelming, particularly if you don’t have a solid background in Computer Science. But the truth is, once you’ve learned a little bit of JavaScript, you can already make some pretty impressive things.
A couple of years back, when I was learning to code, I started working on a side project. I wanted to make something colorful and fun to share with my friends. This is what my app looks like these days:
Mandala Maker user interface
The coolest part about it is the fact that it’s a tool: anyone can use it to create something original and brand new.
In this tutorial, we’ll build a smaller version of this app – a symmetrical drawing tool in ES5, JavaScript and HTML5. The tutorial app will have eight reflections, a color picker and a Clear button. Once we’re done, you’re on your own and can tweak it as you please. Be creative!
Preparations: a blank canvas
The first thing you’ll need for this project is a designated drawing space. We’ll use the HTML5 canvas element and give it a width and a height of 600px (you can set the dimensions to anything else if you like).
Files
Create 3 files: index.html, styles.css, main.js. Don’t forget to include your JS and CSS files in your HTML.
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<link rel="stylesheet" type="text/css" href="style.css">
<script src="main.js"></script>
</head>
<body onload="init()">
<canvas width="600" height="600">
<p>Your browser doesn't support canvas.</p>
</canvas>
</body>
</html>
I’ll ask you to update your HTML file at a later point, but the CSS file we’ll start with will stay the same throughout the project. This is the full CSS we are going to use:
body {
background-color: #ccc;
text-align: center;
}
canvas {
touch-action: none;
background-color: #fff;
}
button {
font-size: 110%;
}
Next steps
We are done with our preparations and ready to move on to the actual tutorial, which is made up of 4 parts:
Building a simple drawing app with one line and one color
Adding a Clear button and a color picker
Adding more functionality: 2 line drawing (add the first reflection)
Adding more functionality: 8 line drawing (add 6 more reflections!)
Interactive demos
This tutorial will be accompanied by four CodePens, one at the end of each section. In my own app I originally used mouse events, and only added touch events when I realized mobile device support was (A) possible, and (B) going to make my app way more accessible. For the sake of code simplicity, I decided that in this tutorial app I will only use one event type, so I picked a third option: pointer events. These are supported by some desktop browsers and some mobile browsers. An up-to-date version of Chrome is probably your best bet.
Part 1: A simple drawing app
Let’s get started with our main.js file. Our basic drawing app will be made up of 6 functions: init, drawLine, stopDrawing, recordPointerLocation, handlePointerMove, handlePointerDown. It also has nine variables:
var canvas, context, w, h,
prevX = 0, currX = 0, prevY = 0, currY = 0,
draw = false;
The variables canvas and context let us manipulate the canvas. w is the canvas width and h is the canvas height. The four coordinates are used for tracking the current and previous location of the pointer. A short line is drawn between (prevX, prevY) and (currX, currY) repeatedly many times while we move the pointer upon the canvas. For your drawing to appear, three conditions must be met: the pointer (be it a finger, a trackpad or a mouse) must be down, it must be moving and the movement has to be on the canvas. If these three conditions are met, the boolean draw is set to true.
1. init
Responsible for canvas set up, this listens to pointer events and the location of their coordinates and sets everything in motion by calling other functions, which in turn handle touch and movement events.
function init() {
canvas = document.querySelector("canvas");
context = canvas.getContext("2d");
w = canvas.width;
h = canvas.height;
canvas.onpointermove = handlePointerMove;
canvas.onpointerdown = handlePointerDown;
canvas.onpointerup = stopDrawing;
canvas.onpointerout = stopDrawing;
}
2. drawLine
This is called to action by handlePointerMove() and draws the pointer path. It only runs if draw = true. It uses canvas methods you can read about in the canvas API documentation. You can also learn to use the canvas element in this tutorial.
lineWidth and linecap set the properties of our paint brush, or digital pen, but pay attention to beginPath and closePath. Between those two is where the magic happens: moveTo and lineTo take canvas coordinates as arguments and draw from (a,b) to (c,d), which is to say from (prevX,prevY) to (currX,currY).
function drawLine() {
var a = prevX,
b = prevY,
c = currX,
d = currY;
context.lineWidth = 4;
context.lineCap = "round";
context.beginPath();
context.moveTo(a, b);
context.lineTo(c, d);
context.stroke();
context.closePath();
}
3. stopDrawing
This is used by init when the pointer is not down (onpointerup) or is out of bounds (onpointerout).
function stopDrawing() {
draw = false;
}
4. recordPointerLocation
This tracks the pointer’s location and stores its coordinates. Also, you need to know that in computer graphics the origin of the coordinate space (0,0) is at the top left corner, and all elements are positioned relative to it. When we use canvas we are dealing with two coordinate spaces: the browser window and the canvas itself. This function converts between the two: it subtracts the canvas offsetLeft and offsetTop so we can later treat the canvas as the only coordinate space. If you are confused, read more about it.
function recordPointerLocation(e) {
prevX = currX;
prevY = currY;
currX = e.clientX - canvas.offsetLeft;
currY = e.clientY - canvas.offsetTop;
}
5. handlePointerMove
This is set by init to run when the pointer moves. It checks if draw = true. If so, it calls recordPointerLocation to get the path and drawLine to draw it.
function handlePointerMove(e) {
if (draw) {
recordPointerLocation(e);
drawLine();
}
}
6. handlePointerDown
This is set by init to run when the pointer is down (finger is on touchscreen or mouse it clicked). If it is, calls recordPointerLocation to get the path and sets draw to true. That’s because we only want movement events from handlePointerMove to cause drawing if the pointer is down.
function handlePointerDown(e) {
recordPointerLocation(e);
draw = true;
}
Finally, we have a working drawing app. But that’s just the beginning!
See the Pen Mandala Maker Tutorial: Part 1 by Hagar Shilo (@hagarsh) on CodePen.
Part 2: Add a Clear button and a color picker
Now we’ll update our HTML file, adding a menu div with an input of the type and class color and a button of the class clear.
<body onload="init()">
<canvas width="600" height="600">
<p>Your browser doesn't support canvas.</p>
</canvas>
<div class="menu">
<input type="color" class="color" />
<button type="button" class="clear">Clear</button>
</div>
</body>
Color picker
This is our new color picker function. It targets the input element by its class and gets its value.
function getColor() {
return document.querySelector(".color").value;
}
Up until now, the app used a default color (black) for the paint brush/digital pen. If we want to change the color we need to use the canvas property strokeStyle. We’ll update drawLine by adding strokeStyle to it and setting it to the input value by calling getColor.
function drawLine() {
//...code...
context.strokeStyle = getColor();
context.lineWidth = 4;
context.lineCap = "round";
//...code...
}
Clear button
This is our new Clear function. It responds to a button click and displays a dialog asking the user if she really wants to delete the drawing.
function clearCanvas() {
if (confirm("Want to clear?")) {
context.clearRect(0, 0, w, h);
}
}
The method clearRect takes four arguments. The first two (0,0) mark the origin, which is actually the top left corner of the canvas. The other two (w,h) mark the full width and height of the canvas. This means the entire canvas will be erased, from the top left corner to the bottom right corner.
If we were to give clearRect a slightly different set of arguments, say (0,0,w/2,h), the result would be different. In this case, only the left side of the canvas would clear up.
Let’s add this event handler to init:
function init() {
//...code...
canvas.onpointermove = handleMouseMove;
canvas.onpointerdown = handleMouseDown;
canvas.onpointerup = stopDrawing;
canvas.onpointerout = stopDrawing;
document.querySelector(".clear").onclick = clearCanvas;
}
See the Pen Mandala Maker Tutorial: Part 2 by Hagar Shilo (@hagarsh) on CodePen.
Part 3: Draw with 2 lines
It’s time to make a line appear where no pointer has gone before. A ghost line!
For that we are going to need four new coordinates: a', b', c' and d' (marked in the code as a_, b_, c_ and d_). In order for us to be able to add the first reflection, first we must decide if it’s going to go over the y-axis or the x-axis. Since this is an arbitrary decision, it doesn’t matter which one we choose. Let’s go with the x-axis.
Here is a sketch to help you grasp the mathematics of reflecting a point across the x-axis. The coordinate space in my sketch is different from my explanation earlier about the way the coordinate space works in computer graphics (more about that in a bit!).
Now, look at A. It shows a point drawn where the pointer hits, and B shows the additional point we want to appear: a reflection of the point across the x-axis. This is our goal.
A sketch illustrating the mathematics of reflecting a point.
What happens to the x coordinates?
The variables a/a' and c/c' correspond to prevX and currX respectively, so we can call them “the x coordinates”. We are reflecting across x, so their values remain the same, and therefore a' = a and c' = c.
What happens to the y coordinates?
What about b' and d'? Those are the ones that have to change, but in what way? Thanks to the slightly misleading sketch I showed you just now (of A and B), you probably think that the y coordinates b' and d' should get the negative values of b and d respectively, but nope. This is computer graphics, remember? The origin is at the top left corner and not at the canvas center, and therefore we get the following values: b = h - b, d' = h - d, where h is the canvas height.
This is the new code for the app’s variables and the two lines: the one that fills the pointer’s path and the one mirroring it across the x-axis.
function drawLine() {
var a = prevX, a_ = a,
b = prevY, b_ = h-b,
c = currX, c_ = c,
d = currY, d_ = h-d;
//... code ...
// Draw line #1, at the pointer's location
context.moveTo(a, b);
context.lineTo(c, d);
// Draw line #2, mirroring the line #1
context.moveTo(a_, b_);
context.lineTo(c_, d_);
//... code ...
}
In case this was too abstract for you, let’s look at some actual numbers to see how this works.
Let’s say we have a tiny canvas of w = h = 10. Now let a = 3, b = 2, c = 4 and d = 3.
So b' = 10 - 2 = 8 and d' = 10 - 3 = 7.
We use the top and the left as references. For the y coordinates this means we count from the top, and 8 from the top is also 2 from the bottom. Similarly, 7 from the top is 3 from the bottom of the canvas. That’s it, really. This is how the single point, and a line (not necessarily a straight one, by the way) is made up of many, many small segments that are similar to point in behavior.
If you are still confused, I don’t blame you.
Here is the result. Draw something and see what happens.
See the Pen Mandala Maker Tutorial: Part 3 by Hagar Shilo (@hagarsh) on CodePen.
Part 4: Draw with 8 lines
I have made yet another confusing sketch, with points C and D, so you understand what we’re trying to do. Later on we’ll look at points E, F, G and H as well. The circled point is the one we’re adding at each particular step. The circled point at C has the coordinates (-3,2) and the circled point at D has the coordinates (-3,-2). Once again, keep in mind that the origin in the sketches is not the same as the origin of the canvas.
A sketch illustrating points C and D.
This is the part where the math gets a bit mathier, as our drawLine function evolves further. We’ll keep using the four new coordinates: a', b', c' and d', and reassign their values for each new location/line. Let’s add two more lines in two new locations on the canvas. Their locations relative to the first two lines are exactly what you see in the sketch above, though the calculation required is different (because of the origin points being different).
function drawLine() {
//... code ...
// Reassign values
a_ = w-a; b_ = b;
c_ = w-c; d_ = d;
// Draw the 3rd line
context.moveTo(a_, b_);
context.lineTo(c_, d_);
// Reassign values
a_ = w-a; b_ = h-b;
c_ = w-c; d_ = h-d;
// Draw the 4th line
context.moveTo(a_, b_);
context.lineTo(c_, d_);
//... code ...
What is happening?
You might be wondering why we use w and h as separate variables, even though we know they have the same value. Why complicate the code this way for no apparent reason? That’s because we want the symmetry to hold for a rectangular canvas as well, and this way it will.
Also, you may have noticed that the values of a' and c' are not reassigned when the fourth line is created. Why write their value assignments twice? It’s for readability, documentation and communication. Maintaining the quadruple structure in the code is meant to help you remember that all the while we are dealing with two y coordinates (current and previous) and two x coordinates (current and previous).
What happens to the x coordinates?
As you recall, our x coordinates are a (prevX) and c (currX).
For the third line we are adding, a' = w - a and c' = w - c, which means…
For the fourth line, the same thing happens to our x coordinates a and c.
What happens to the y coordinates?
As you recall, our y coordinates are b (prevY) and d (currY).
For the third line we are adding, b' = b and d' = d, which means the y coordinates are the ones not changing this time, making this is a reflection across the y-axis.
For the fourth line, b' = h - b and d' = h - d, which we’ve seen before: that’s a reflection across the x-axis.
We have four more lines, or locations, to define. Note: the part of the code that’s responsible for drawing a micro-line between the newly calculated coordinates is always the same:
context.moveTo(a_, b_);
context.lineTo(c_, d_);
We can leave it out of the next code snippets and just focus on the calculations, i.e, the reassignments.
Once again, we need some concrete examples to see where we’re going, so here’s another sketch! The circled point E has the coordinates (2,3) and the circled point F has the coordinates (2,-3). The ability to draw at A but also make the drawing appear at E and F (in addition to B, C and D that we already dealt with) is the functionality we are about to add to out code.
A sketch illustrating points E and F.
This is the code for E and F:
// Reassign for 5
a_ = w/2+h/2-b; b_ = w/2+h/2-a;
c_ = w/2+h/2-d; d_ = w/2+h/2-c;
// Reassign for 6
a_ = w/2+h/2-b; b_ = h/2-w/2+a;
c_ = w/2+h/2-d; d_ = h/2-w/2+c;
Their x coordinates are identical and their y coordinates are reversed to one another.
This one will be out final sketch. The circled point G has the coordinates (-2,3) and the circled point H has the coordinates (-2,-3).
A sketch illustrating points G and H.
This is the code:
// Reassign for 7
a_ = w/2-h/2+b; b_ = w/2+h/2-a;
c_ = w/2-h/2+d; d_ = w/2+h/2-c;
// Reassign for 8
a_ = w/2-h/2+b; b_ = h/2-w/2+a;
c_ = w/2-h/2+d; d_ = h/2-w/2+c;
//...code...
}
Once again, the x coordinates of these two points are the same, while the y coordinates are different. And once again I won’t go into the full details, since this has been a long enough journey as it is, and I think we’ve covered all the important principles. But feel free to play around with the code and change it. I really recommend commenting out the code for some of the points to see what your drawing looks like without them.
I hope you had fun learning! This is our final app:
See the Pen Mandala Maker Tutorial: Part 4 by Hagar Shilo (@hagarsh) on CodePen. |
2018 |
Hagar Shilo |
hagarshilo |
2018-12-02T00:00:00+00:00 |
https://24ways.org/2018/the-art-of-mathematics/ |
code |
| 186 |
The Web Is Your CMS |
It is amazing what you can do these days with the services offered on the web. Flickr stores terabytes of photos for us and converts them automatically to all kind of sizes, finds people in them and even allows us to edit them online. YouTube does almost the same complete job with videos, LinkedIn allows us to maintain our CV, Delicious our bookmarks and so on.
We don’t have to do these tasks ourselves any more, as all of these systems also come with ways to use the data in the form of Application Programming Interfaces, or APIs for short. APIs give us raw data when we send requests telling the system what we want to get back.
The problem is that every API has a different idea of what is a simple way of accessing this data and in which format to give it back.
Making it easier to access APIs
What we need is a way to abstract the pains of different data formats and authentication formats away from the developer — and this is the purpose of the Yahoo Query Language, or YQL for short.
Libraries like jQuery and YUI make it easy and reliable to use JavaScript in browsers (yes, even IE6) and YQL allows us to access web services and even the data embedded in web documents in a simple fashion – SQL style.
Select * from the web and filter it the way I want
YQL is a web service that takes a few inputs itself:
A query that tells it what to get, update or access
An output format – XML, JSON, JSON-P or JSON-P-X
A callback function (if you defined JSON-P or JSON-P-X)
You can try it out yourself – check out this link to get back Flickr photos for the search term ‘santa’*%20from%20flickr.photos.search%20where%20text%3D%22santa%22&format=xml in XML format. The YQL query for this is
select * from flickr.photos.search where text="santa"
The easiest way to take your first steps with YQL is to look at the console. There you get sample queries, access to all the data sources available to you and you can easily put together complex queries. In this article, however, let’s use PHP to put together a web page that pulls in Flickr photos, blog posts, Videos from YouTube and latest bookmarks from Delicious.
Check out the demo and get the source code on GitHub.
<?php
/* YouTube RSS */
$query = 'select description from rss(5) where url="http://gdata.youtube.com/feeds/base/users/chrisheilmann/uploads?alt=rss&v=2&orderby=published&client=ytapi-youtube-profile";';
/* Flickr search by user id */
$query .= 'select farm,id,owner,secret,server,title from flickr.photos.search where user_id="11414938@N00";';
/* Delicious RSS */
$query .= 'select title,link from rss where url="http://feeds.delicious.com/v2/rss/codepo8?count=10";';
/* Blog RSS */
$query .= 'select title,link from rss where url="http://feeds.feedburner.com/wait-till-i/gwZf"';
/* The YQL web service root with JSON as the output */
$root = 'http://query.yahooapis.com/v1/public/yql?format=json&env=store%3A%2F%2Fdatatables.org%2Falltableswithkeys';
/* Assemble the query */
$query = "select * from query.multi where queries='".$query."'";
$url = $root . '&q=' . urlencode($query);
/* Do the curl call (access the data just like a browser would) */
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, $url);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false);
curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, false);
$output = curl_exec($ch);
curl_close($ch);
$data = json_decode($output);
$results = $data->query->results->results;
/* YouTube output */
$youtube = '<ul id="youtube">';
foreach($results[0]->item as $r){
$cleanHTML = undoYouTubeMarkupCrimes($r->description);
$youtube .= '<li>'.$cleanHTML.'</li>';
}
$youtube .= '</ul>';
/* Flickr output */
$flickr = '<ul id="flickr">';
foreach($results[1]->photo as $r){
$flickr .= '<li>'.
'<a href="http://www.flickr.com/photos/codepo8/'.$r->id.'/">'.
'<img src="http://farm' .$r->farm . '.static.flickr.com/'.
$r->server . '/' . $r->id . '_' . $r->secret .
'_s.jpg" alt="'.$r->title.'"></a></li>';
}
$flickr .= '</ul>';
/* Delicious output */
$delicious = '<ul id="delicious">';
foreach($results[2]->item as $r){
$delicious .= '<li><a href="'.$r->link.'">'.$r->title.'</a></li>';
}
$delicious .= '</ul>';
/* Blog output */
$blog = '<ul id="blog">';
foreach($results[3]->item as $r){
$blog .= '<li><a href="'.$r->link.'">'.$r->title.'</a></li>';
}
$blog .= '</ul>';
function undoYouTubeMarkupCrimes($str){
$cleaner = preg_replace('/555px/','100%',$str);
$cleaner = preg_replace('/width="[^"]+"/','',$cleaner);
$cleaner = preg_replace('/<tbody>/','<colgroup><col width="20%"><col width="50%"><col width="30%"></colgroup><tbody>',$cleaner);
return $cleaner;
}
?>
What we are doing here is create a few different YQL statements and queue them together with the query.multi table. Each of these can be run inside YQL itself. Check out the YouTube, Flickr, Delicious and Blog example in the console if you don’t believe me. The benefit of using this table is that we don’t make individual requests for each query but we get all the data in one single request – which means a much better performing solution as the YQL server farm is faster on the web than our servers.
We point the query to the YQL web service end point and get the resulting data using cURL. All that we need to do then is to convert the returned data to HTML lists that can be printed out inside an HTML template.
Mixing, matching and using HTML as a data source
This was a simple example of what YQL can do for you. Where it gets really powerful however is by mixing and matching different APIs. YQL is also a good tool to get information from HTML documents. By using the html table you can load the content of an HTML document (which gets fixed automatically by HTMLTidy) and use XPATH to filter down results to what you need. Take the following example which takes headlines from the news.bbc.co.uk homepage and runs the results through Yahoo’s Term Extractor API to give you a list of currently hot topics.
select * from search.termextract where context in (
select content from html where url="http://news.bbc.co.uk" and xpath="//table[@width=800]//a"
)
Try it out in the console or see the results here. In English, this means:
Go to http://news.bbc.co.uk and get me the HTML
Run it through HTML Tidy to clean it up.
Get me only the links inside the table with an attribute of width and the value 800
Get only the content of the link and for each of the links
Take the content and send it as context to the Yahoo Term Extractor API
If we choose JSON-P as the output format we can use the outcome directly in JavaScript (see this demo or see its source):
<ul id="hottopics"></ul>
<script type="text/javascript">
function hottopics(o){
var res = o.query.results.Result,
all = res.length,
topics = {},
out = [],
html = '',
i=0;
/* create hash from topics to prevent repetition */
for(i=0;i<all;i++){
topics[res[i]] = res[i];
};
for(i in topics){
out.push(i);
};
html = '<li>' + out.join('</li><li>') + '</li>';
document.getElementById('hottopics').innerHTML = html;
};
</script>
<script type="text/javascript" src="http://query.yahooapis.com/v1/public/yql?q=select%20content%20from%20search.termextract%20where %20context%20in%20(select%20content%20from%20html%20where%20url%3D%22http%3A%2F%2Fnews.bbc.co.uk%22%20and%20xpath%3D%22%2F%2Ftable%5B%40width%3D800%5D%2F%2Fa%22)&format=json&callback=hottopics"></script>
Using JSON, we can also use PHP which means the demo works for everybody – not only those with JavaScript enabled (see this demo or see its source):
<ul id="hottopics"><li>
<?php
$url = 'http://query.yahooapis.com/v1/public/yql?q=select%20content'.
'%20from%20search.termextract%20where%20context%20in'.
'%20(select%20content%20from%20html%20where%20url%3D%22'.
'http%3A%2F%2Fnews.bbc.co.uk%22%20and%20xpath%3D%22%2F%2F'.
'table%5B%40width%3D800%5D%2F%2Fa%22)&format=json';
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, $url);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false);
curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, false);
$output = curl_exec($ch);
curl_close($ch);
$data = json_decode($output);
$topics = array_unique($data->query->results->Result);
echo join('</li><li>',$topics);
?>
</li></ul>
Summary
This article could only scratch the surface of YQL. You have not only read access to the web but you can also write to web services. For example you can update Twitter, post to your WordPress blog or shorten a URL with bit.ly. Using Open Tables you can add any web service to the YQL interface and you can even run server-side JavaScript which is for example useful to return Flickr photos as HTML or get the HTML content from a document that needs POST data.
The web of data is already here, and using YQL you don’t have to be a web services expert to use it and be part of it. |
2009 |
Christian Heilmann |
chrisheilmann |
2009-12-17T00:00:00+00:00 |
https://24ways.org/2009/the-web-is-your-cms/ |
code |
| 16 |
URL Rewriting for the Fearful |
I think it was Marilyn Monroe who said, “If you can’t handle me at my worst, please just fix these rewrite rules, I’m getting an internal server error.” Even the blonde bombshell hated configuring URL rewrites on her website, and I think most of us know where she was coming from.
The majority of website projects I work on require some amount of URL rewriting, and I find it mildly enjoyable — I quite like a good rewrite rule. I suspect you may not share my glee, so in this article we’re going to go back to basics to try to make the whole rigmarole more understandable.
When we think about URL rewriting, usually that means adding some rules to an .htaccess file for an Apache web server. As that’s the most common case, that’s what I’ll be sticking to here. If you work with a different server, there’s often documentation specifically for translating from Apache’s mod_rewrite rules. I even found an automatic converter for nginx.
This isn’t going to be a comprehensive guide to every URL rewriting problem you might ever have. That would take us until Christmas. If you consider yourself a trial-and-error dabbler in the HTTP 500-infested waters of URL rewriting, then hopefully this will provide a little bit more of a basis to help you figure out what you’re doing. If you’ve ever found yourself staring at the white screen of death after screwing up your .htaccess file, don’t worry. As Michael Jackson once insipidly whined, you are not alone.
The basics
Rewrite rules form part of the Apache web server’s configuration for a website, and can be placed in a number of different locations as part of your virtual host configuration. By far the simplest and most portable option is to use an .htaccess file in your website root. Provided your server has mod_rewrite available, all you need to do to kick things off in your .htaccess file is:
RewriteEngine on
The general formula for a rewrite rule is:
RewriteRule URL/to/match URL/to/use/if/it/matches [options]
When we talk about URL rewriting, we’re normally talking about one of two things: redirecting the browser to a different URL; or rewriting the URL internally to use a particular file. We’ll look at those in turn.
Redirects
Redirects match an incoming URL, and then redirect the user’s browser to a different address. These can be useful for maintaining legacy URLs if content changes location as part of a site redesign. Redirecting the old URL to the new location makes sure that any incoming links, such as those from search engines, continue to work.
In 1998, Sir Tim Berners-Lee wrote that Cool URIs don’t change, encouraging us all to go the extra mile to make sure links keep working forever. I think that sometimes it’s fine to move things around — especially to correct bad URL design choices of the past — provided that you can do so while keeping those old URLs working. That’s where redirects can help.
A redirect might look like this
RewriteRule ^article/used/to/be/here.php$ /article/now/lives/here/ [R=301,L]
Rewriting
By default, web servers closely map page URLs to the files in your site. On receiving a request for http://example.com/about/history.html the server goes to the configured folder for the example.com website, and then goes into the about folder and returns the history.html file.
A rewrite rule changes that process by breaking the direct relationship between the URL and the file system. “When there’s a request for /about/history.html” a rewrite rule might say, “use the file /about_section.php instead.”
This opens up lots of possibilities for creative ways to map URLs to the files that know how to serve up the page. Most MVC frameworks will have a single rule to rewrite all page URLs to one single file. That file will be a script which kicks off the framework to figure out what to do to serve the page.
RewriteRule ^for/this/url/$ /use/this/file.php [L]
Matching patterns
By now you’ll have noted the weird ^ and $ characters wrapped around the URL we’re trying to match. That’s because what we’re actually using here is a pattern. Technically, it is what’s called a Perl Compatible Regular Expression (PCRE) or simply a regex or regexp. We’ll call it a pattern because we’re not animals.
What are these patterns? If I asked you to enter your credit card expiry date as MM/YY then chances are you’d wonder what I wanted your credit card details for, but you’d know that I wanted a two-digit month, a slash, and a two-digit year. That’s not a regular expression, but it’s the same idea: using some placeholder characters to define the pattern of the input you’re trying to match.
We’ve already met two regexp characters.
^
Matches the beginning of a string
$
Matches the end of a string
When a pattern starts with ^ and ends with $ it’s to make sure we match the complete URL start to finish, not just part of it. There are lots of other ways to match, too:
[0-9]
Matches a number, 0–9. [2-4] would match numbers 2 to 4 inclusive.
[a-z]
Matches lowercase letters a–z
[A-Z]
Matches uppercase letters A–Z
[a-z0-9]
Combining some of these, this matches letters a–z and numbers 0–9
These are what we call character groups. The square brackets basically tell the server to match from the selection of characters within them. You can put any specific characters you’re looking for within the brackets, as well as the ranges shown above.
However, all these just match one single character. [0-9] would match 8 but not 84 — to match 84 we’d need to use [0-9] twice.
[0-9][0-9]
So, if we wanted to match 1984 we could to do this:
[0-9][0-9][0-9][0-9]
…but that’s getting silly. Instead, we can do this:
[0-9]{4}
That means any character between 0 and 9, four times. If we wanted to match a number, but didn’t know how long it might be (for example, a database ID in the URL) we could use the + symbol, which means one or more.
[0-9]+
This now matches 1, 123 and 1234567.
Putting it into practice
Let’s say we need to write a rule to match article URLs for this website, and to rewrite them to use /article.php under the hood. The articles all have URLs like this:
2013/article-title/
They start with a year (from 2005 up to 2013, currently), a slash, and then have a URL-safe version of the article title (a slug), ending in a slash. We’d match it like this:
^[0-9]{4}/[a-z0-9-]+/$
If that looks frightening, don’t worry. Breaking it down, from the start of the URL (^) we’re looking for four numbers ([0-9]{4}). Then a slash — that’s just literal — and then anything lowercase a–z or 0–9 or a dash ([a-z0-9-]) one or more times (+), ending in a slash (/$).
Putting that into a rewrite rule, we end up with this:
RewriteRule ^[0-9]{4}/[a-z0-9-]+/$ /article.php
We’re getting close now. We can match the article URLs and rewrite them to use article.php. Now we just need to make sure that article.php knows which article it’s supposed to display.
Capturing groups, and replacements
When rewriting URLs you’ll often want to take important parts of the URL you’re matching and pass them along to the script that handles the request. That’s usually done by adding those parts of the URL on as query string arguments. For our example, we want to make sure that article.php knows the year and the article title we’re looking for. That means we need to call it like this:
/article.php?year=2013&slug=article-title
To do this, we need to mark which parts of the pattern we want to reuse in the destination. We do this with round brackets or parentheses. By placing parentheses around parts of the pattern we want to reuse, we create what’s called a capturing group. To capture an important part of the source URL to use in the destination, surround it in parentheses.
Our pattern now looks like this, with parentheses around the parts that match the year and slug, but ignoring the slashes:
^([0-9]{4})/([a-z0-9-]+)/$
To use the capturing groups in the destination URL, we use the dollar sign and the number of the group we want to use. So, the first capturing group is $1, the second is $2 and so on. (The $ is unrelated to the end-of-pattern $ we used before.)
RewriteRule ^([0-9]{4})/([a-z0-9-]+)/$ /article.php?year=$1&slug=$2
The value of the year capturing group gets used as $1 and the article title slug is $2. Had there been a third group, that would be $3 and so on. In regexp parlance, these are called back-references as they refer back to the pattern.
Options
Several brain-taxing minutes ago, I mentioned some options as the final part of a rewrite rule. There are lots of options (or flags) you can set to change how the rule is processed. The most useful (to my mind) are:
R=301
Perform an HTTP 301 redirect to send the user’s browser to the new URL. A status of 301 means a resource has moved permanently and so it’s a good way of both redirecting the user to the new URL, and letting search engines know to update their indexes.
L
Last. If this rule matches, don’t bother processing the following rules.
Options are set in square brackets at the end of the rule. You can set multiple options by separating them with commas:
RewriteRule ^([0-9]{4})/([a-z0-9-]+)/$ /article.php?year=$1&slug=$2 [L]
or
RewriteRule ^about/([a-z0-9-]+).jsp/$ /about/$1/ [R=301,L]
Common pitfalls
Once you’ve built up a few rewrite rules, things can start to go wrong. You may have been there: a rule which looks perfectly good is somehow not matching. One common reason for this is hidden behind that [L] flag.
L for Last is a useful option to tell the rewrite engine to stop once the rule has been matched. This is what it does — the remaining rules in the .htaccess file are then ignored. However, once a URL has been rewritten, the entire set of rules are then run again on the new URL. If the new URL matches any of the rules, that too will be rewritten and on it goes.
One way to avoid this problem is to keep your ‘real’ pages under a folder path that will never match one of your rules, or that you can exclude from the rewrite rules.
Useful snippets
I find myself reusing the same few rules over and over again, just with minor changes. Here are some useful examples to refer back to.
Excluding a directory
As mentioned above, if you’re rewriting lots of fancy URLs to a collection of real files it can be helpful to put those files in a folder and exclude it from rewrite rules. This helps solve the issue of rewrite rules reapplying to your newly rewritten URL. To exclude a directory, put a rule like this at the top of your file, before your other rules. Our files are in a folder called _source, the dash in the rule means do nothing, and the L flag means the following rules won’t be applied.
RewriteRule ^_source - [L]
This is also useful for excluding things like CMS folders from your website’s rewrite rules
RewriteRule ^perch - [L]
Adding or removing www from the domain
Some folk like to use a www and others don’t. Usually, it’s best to pick one and go with it, and redirect the one you don’t want. On this site, we don’t use www.24ways.org so we redirect those requests to 24ways.org.
This uses a RewriteCond which is like an if for a rewrite rule: “If this condition matches, then apply the following rule.” In this case, it’s if the HTTP HOST (or domain name, basically) matches this pattern, then redirect everything:
RewriteCond %{HTTP_HOST} ^www.24ways.org$ [NC]
RewriteRule ^(.*)$ http://24ways.org/$1 [R=301,L]
The [NC] flag means ‘no case’ — the match is case-insensitive. The dots in the domain are escaped with a backslash, as a dot is a regular expression character which means match anything, so we escape it because we literally mean a dot in this instance.
Removing file extensions
Sometimes all you need to do to tidy up a URL is strip off the technology-specific file extension, so that /about/history.php becomes /about/history. This is easily achieved with the help of some more rewrite conditions.
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_FILENAME}.php -f
RewriteRule ^(.+)$ $1.php [L,QSA]
This says if the file being asked for isn’t a file (!-f) and if it isn’t a directory (!-d) and if the file name plus .php is an actual file (-f) then rewrite by adding .php on the end. The QSA flag means ‘query string append’: append the existing query string onto the rewritten URL.
It’s these sorts of more generic catch-all rules that you need to watch out for when your .htaccess gets rerun after a successful match. Without care they can easily rematch the newly rewritten URL.
Logging for when it all goes wrong
Although not possible within your .htaccess file, if you have access to your Apache configuration files you can enable rewrite logging. This can be useful to track down where a rule is going wrong, if it’s matching incorrectly or failing to match. It also gives you an overview of the amount of work being done by the rewrite engine, enabling you to rearrange your rules and maximise performance.
RewriteEngine On
RewriteLog "/full/system/path/to/rewrite.log"
RewriteLogLevel 5
To be doubly clear: this will not work from an .htaccess file — it needs to be added to the main Apache configuration files. (I sometimes work using MAMP PRO locally on my Mac, and this can be pasted into the snappily named Customized virtual host general settings box in the Advanced tab for your site.)
The white screen of death
One of the most frustrating things when working with rewrite rules is that when you make a mistake it can result in the server returning an HTTP 500 Internal Server Error. This in itself isn’t an error message, of course. It’s more of a notification that an error has occurred. The real error message can usually be found in your Apache error log.
If you have access to your server logs, check the Apache error log and you’ll usually find a much more descriptive error message, pointing you towards your mistake. (Again, if using MAMP PRO, go to Server, Apache and the View Log button.)
In conclusion
Rewriting URLs can be a bear, but the advantages are clear. Keeping a tidy URL structure, disconnected from the technology or file structure of your site can result in URLs that are easier to use and easier to maintain into the future.
If you’re redesigning a site, remember that cool URIs don’t change, so budget some time to make sure that any content you move has a rewrite rule associated with it to keep any links working.
Further reading
To find out more about URL rewriting and perhaps even learn more about regular expressions, I can recommend the following resources.
From the horse’s mouth, the Apache mod_rewrite documentation
Particularly useful with that documentation is the RewriteRule Flags listing
You may wish to don sunglasses to follow the otherwise comprehensive Regular-Expressions.info tutorial
Friend of 24 ways, Neil Crosby has a mod_rewrite Beginner’s Guide which I’ve found handy over the years.
As noted at the start, this isn’t a fully comprehensive guide, but I hope it’s useful in finding your feet with a powerful but sometimes annoying technology. Do you have useful snippets you often use on projects? Feel free to share them in the comments. |
2013 |
Drew McLellan |
drewmclellan |
2013-12-01T00:00:00+00:00 |
https://24ways.org/2013/url-rewriting-for-the-fearful/ |
code |
| 49 |
Universal React |
One of the libraries to receive a huge amount of focus in 2015 has been ReactJS, a library created by Facebook for building user interfaces and web applications.
More generally we’ve seen an even greater rise in the number of applications built primarily on the client side with most of the logic implemented in JavaScript. One of the main issues with building an app in this way is that you immediately forgo any customers who might browse with JavaScript turned off, and you can also miss out on any robots that might visit your site to crawl it (such as Google’s search bots). Additionally, we gain a performance improvement by being able to render from the server rather than having to wait for all the JavaScript to be loaded and executed.
The good news is that this problem has been recognised and it is possible to build a fully featured client-side application that can be rendered on the server. The way in which these apps work is as follows:
The user visits www.yoursite.com and the server executes your JavaScript to generate the HTML it needs to render the page.
In the background, the client-side JavaScript is executed and takes over the duty of rendering the page.
The next time a user clicks, rather than being sent to the server, the client-side app is in control.
If the user doesn’t have JavaScript enabled, each click on a link goes to the server and they get the server-rendered content again.
This means you can still provide a very quick and snappy experience for JavaScript users without having to abandon your non-JS users. We achieve this by writing JavaScript that can be executed on the server or on the client (you might have heard this referred to as isomorphic) and using a JavaScript framework that’s clever enough handle server- or client-side execution. Currently, ReactJS is leading the way here, although Ember and Angular are both working on solutions to this problem.
It’s worth noting that this tutorial assumes some familiarity with React in general, its syntax and concepts. If you’d like a refresher, the ReactJS docs are a good place to start.
Getting started
We’re going to create a tiny ReactJS application that will work on the server and the client. First we’ll need to create a new project and install some dependencies. In a new, blank directory, run:
npm init -y
npm install --save ejs express react react-router react-dom
That will create a new project and install our dependencies:
ejs is a templating engine that we’ll use to render our HTML on the server.
express is a small web framework we’ll run our server on.
react-router is a popular routing solution for React so our app can fully support and respect URLs.
react-dom is a small React library used for rendering React components.
We’re also going to write all our code in ECMAScript 6, and therefore need to install BabelJS and configure that too.
npm install --save-dev babel-cli babel-preset-es2015 babel-preset-react
Then, create a .babelrc file that contains the following:
{
"presets": ["es2015", "react"]
}
What we’ve done here is install Babel’s command line interface (CLI) tool and configured it to transform our code from ECMAScript 6 (or ES2015) to ECMAScript 5, which is more widely supported. We’ll need the React transforms when we start writing JSX when working with React.
Creating a server
For now, our ExpressJS server is pretty straightforward. All we’ll do is render a view that says ‘Hello World’. Here’s our server code:
import express from 'express';
import http from 'http';
const app = express();
app.use(express.static('public'));
app.set('view engine', 'ejs');
app.get('*', (req, res) => {
res.render('index');
});
const server = http.createServer(app);
server.listen(3003);
server.on('listening', () => {
console.log('Listening on 3003');
});
Here we’re using ES6 modules, which I wrote about on 24 ways last year, if you’d like a reminder. We tell the app to render the index view on any GET request (that’s what app.get('*') means, the wildcard matches any route).
We now need to create the index view file, which Express expects to be defined in views/index.ejs:
<!DOCTYPE html>
<html>
<head>
<title>My App</title>
</head>
<body>
Hello World
</body>
</html>
Finally, we’re ready to run the server. Because we installed babel-cli earlier we have access to the babel-node executable, which will transform all your code before running it through node. Run this command:
./node_modules/.bin/babel-node server.js
And you should now be able to visit http://localhost:3003 and see ‘Hello World’ right there:
Building the React app
Now we’ll build the React application entirely on the server, before adding the client-side JavaScript right at the end. Our app will have two routes, / and /about which will both show a small amount of content. This will demonstrate how to use React Router on the server side to make sure our React app plays nicely with URLs.
Firstly, let’s update views/index.ejs. Our server will figure out what HTML it needs to render, and pass that into the view. We can pass a value into our view when we render it, and then use EJS syntax to tell it to output that data. Update the template file so the body looks like so:
<body>
<%- markup %>
</body>
Next, we’ll define the routes we want our app to have using React Router. For now we’ll just define the index route, and not worry about the /about route quite yet. We could define our routes in JSX, but I think for server-side rendering it’s clearer to define them as an object. Here’s what we’re starting with:
const routes = {
path: '',
component: AppComponent,
childRoutes: [
{
path: '/',
component: IndexComponent
}
]
}
These are just placed at the top of server.js, after the import statements. Later we’ll move these into a separate file, but for now they are fine where they are.
Notice how I define first that the AppComponent should be used at the '' path, which effectively means it matches every single route and becomes a container for all our other components. Then I give it a child route of /, which will match the IndexComponent. Before we hook these routes up with our server, let’s quickly define components/app.js and components/index.js. app.js looks like so:
import React from 'react';
export default class AppComponent extends React.Component {
render() {
return (
<div>
<h2>Welcome to my App</h2>
{ this.props.children }
</div>
);
}
}
When a React Router route has child components, they are given to us in the props under the children key, so we need to include them in the code we want to render for this component. The index.js component is pretty bland:
import React from 'react';
export default class IndexComponent extends React.Component {
render() {
return (
<div>
<p>This is the index page</p>
</div>
);
}
}
Server-side routing with React Router
Head back into server.js, and firstly we’ll need to add some new imports:
import React from 'react';
import { renderToString } from 'react-dom/server';
import { match, RoutingContext } from 'react-router';
import AppComponent from './components/app';
import IndexComponent from './components/index';
The ReactDOM package provides react-dom/server which includes a renderToString method that takes a React component and produces the HTML string output of the component. It’s this method that we’ll use to render the HTML from the server, generated by React. From the React Router package we use match, a function used to find a matching route for a URL; and RoutingContext, a React component provided by React Router that we’ll need to render. This wraps up our components and provides some functionality that ties React Router together with our app. Generally you don’t need to concern yourself about how this component works, so don’t worry too much.
Now for the good bit: we can update our app.get('*') route with the code that matches the URL against the React routes:
app.get('*', (req, res) => {
// routes is our object of React routes defined above
match({ routes, location: req.url }, (err, redirectLocation, props) => {
if (err) {
// something went badly wrong, so 500 with a message
res.status(500).send(err.message);
} else if (redirectLocation) {
// we matched a ReactRouter redirect, so redirect from the server
res.redirect(302, redirectLocation.pathname + redirectLocation.search);
} else if (props) {
// if we got props, that means we found a valid component to render
// for the given route
const markup = renderToString(<RoutingContext {...props} />);
// render `index.ejs`, but pass in the markup we want it to display
res.render('index', { markup })
} else {
// no route match, so 404. In a real app you might render a custom
// 404 view here
res.sendStatus(404);
}
});
});
We call match, giving it the routes object we defined earlier and req.url, which contains the URL of the request. It calls a callback function we give it, with err, redirectLocation and props as the arguments. The first two conditionals in the callback function just deal with an error occuring or a redirect (React Router has built in redirect support). The most interesting bit is the third conditional, else if (props). If we got given props and we’ve made it this far it means we found a matching component to render and we can use this code to render it:
...
} else if (props) {
// if we got props, that means we found a valid component to render
// for the given route
const markup = renderToString(<RoutingContext {...props} />);
// render `index.ejs`, but pass in the markup we want it to display
res.render('index', { markup })
} else {
...
}
The renderToString method from ReactDOM takes that RoutingContext component we mentioned earlier and renders it with the properties required. Again, you need not concern yourself with what this specific component does or what the props are. Most of this is data that React Router provides for us on top of our components.
Note the {...props}, which is a neat bit of JSX syntax that spreads out our object into key value properties. To see this better, note the two pieces of JSX code below, both of which are equivalent:
<MyComponent a="foo" b="bar" />
// OR:
const props = { a: "foo", b: "bar" };
<MyComponent {...props} />
Running the server again
I know that felt like a lot of work, but the good news is that once you’ve set this up you are free to focus on building your React components, safe in the knowledge that your server-side rendering is working. To check, restart the server and head to http://localhost:3003 once more. You should see it all working!
Refactoring and one more route
Before we move on to getting this code running on the client, let’s add one more route and do some tidying up. First, move our routes object out into routes.js:
import AppComponent from './components/app';
import IndexComponent from './components/index';
const routes = {
path: '',
component: AppComponent,
childRoutes: [
{
path: '/',
component: IndexComponent
}
]
}
export { routes };
And then update server.js. You can remove the two component imports and replace them with:
import { routes } from './routes';
Finally, let’s add one more route for ./about and links between them. Create components/about.js:
import React from 'react';
export default class AboutComponent extends React.Component {
render() {
return (
<div>
<p>A little bit about me.</p>
</div>
);
}
}
And then you can add it to routes.js too:
import AppComponent from './components/app';
import IndexComponent from './components/index';
import AboutComponent from './components/about';
const routes = {
path: '',
component: AppComponent,
childRoutes: [
{
path: '/',
component: IndexComponent
},
{
path: '/about',
component: AboutComponent
}
]
}
export { routes };
If you now restart the server and head to http://localhost:3003/about` you’ll see the about page!
For the finishing touch we’ll use the React Router link component to add some links between the pages. Edit components/app.js to look like so:
import React from 'react';
import { Link } from 'react-router';
export default class AppComponent extends React.Component {
render() {
return (
<div>
<h2>Welcome to my App</h2>
<ul>
<li><Link to='/'>Home</Link></li>
<li><Link to='/about'>About</Link></li>
</ul>
{ this.props.children }
</div>
);
}
}
You can now click between the pages to navigate. However, everytime we do so the requests hit the server. Now we’re going to make our final change, such that after the app has been rendered on the server once, it gets rendered and managed in the client, providing that snappy client-side app experience.
Client-side rendering
First, we’re going to make a small change to views/index.ejs. React doesn’t like rendering directly into the body and will give a warning when you do so. To prevent this we’ll wrap our app in a div:
<body>
<div id="app"><%- markup %></div>
<script src="build.js"></script>
</body>
I’ve also added in a script tag to build.js, which is the file we’ll generate containing all our client-side code.
Next, create client-render.js. This is going to be the only bit of JavaScript that’s exclusive to the client side. In it we need to pull in our routes and render them to the DOM.
import React from 'react';
import ReactDOM from 'react-dom';
import { Router } from 'react-router';
import { routes } from './routes';
import createBrowserHistory from 'history/lib/createBrowserHistory';
ReactDOM.render(
<Router routes={routes} history={createBrowserHistory()} />,
document.getElementById('app')
)
The first thing you might notice is the mention of createBrowserHistory. React Router is built on top of the history module, a module that listens to the browser’s address bar and parses the new location. It has many modes of operation: it can keep track using a hashbang, such as http://localhost/#!/about (this is the default), or you can tell it to use the HTML5 history API by calling createBrowserHistory, which is what we’ve done. This will keep the URLs nice and neat and make sure the client and the server are using the same URL structure. You can read more about React Router and histories in the React Router documentation.
Finally we use ReactDOM.render and give it the Router component, telling it about all our routes, and also tell ReactDOM where to render, the #app element.
Generating build.js
We’re actually almost there! The final thing we need to do is generate our client side bundle. For this we’re going to use webpack, a module bundler that can take our application, follow all the imports and generate one large bundle from them. We’ll install it and babel-loader, a webpack plugin for transforming code through Babel.
npm install --save-dev webpack babel-loader
To run webpack we just need to create a configuration file, called webpack.config.js. Create the file in the root of our application and add the following code:
var path = require('path');
module.exports = {
entry: path.join(process.cwd(), 'client-render.js'),
output: {
path: './public/',
filename: 'build.js'
},
module: {
loaders: [
{
test: /.js$/,
loader: 'babel'
}
]
}
}
Note first that this file can’t be written in ES6 as it doesn’t get transformed. The first thing we do is tell webpack the main entry point for our application, which is client-render.js. We use process.cwd() because webpack expects an exact location – if we just gave it the string ‘client-render.js’, webpack wouldn’t be able to find it.
Next, we tell webpack where to output our file, and here I’m telling it to place the file in public/build.js. Finally we tell webpack that every time it hits a file that ends in .js, it should use the babel-loader plugin to transform the code first.
Now we’re ready to generate the bundle!
./node_modules/.bin/webpack
This will take a fair few seconds to run (on my machine it’s about seven or eight), but once it has it will have created public/build.js, a client-side bundle of our application. If you restart your server once more you’ll see that we can now navigate around our application without hitting the server, because React on the client takes over. Perfect!
The first bundle that webpack generates is pretty slow, but if you run webpack -w it will go into watch mode, where it watches files for changes and regenerates the bundle. The key thing is that it only regenerates the small pieces of the bundle it needs, so while the first bundle is very slow, the rest are lightning fast. I recommend leaving webpack constantly running in watch mode when you’re developing.
Conclusions
First, if you’d like to look through this code yourself you can find it all on GitHub. Feel free to raise an issue there or tweet me if you have any problems or would like to ask further questions.
Next, I want to stress that you shouldn’t use this as an excuse to build all your apps in this way. Some of you might be wondering whether a static site like the one we built today is worth its complexity, and you’d be right. I used it as it’s an easy example to work with but in the future you should carefully consider your reasons for wanting to build a universal React application and make sure it’s a suitable infrastructure for you.
With that, all that’s left for me to do is wish you a very merry Christmas and best of luck with your React applications! |
2015 |
Jack Franklin |
jackfranklin |
2015-12-05T00:00:00+00:00 |
https://24ways.org/2015/universal-react/ |
code |
| 71 |
Upping Your Web Security Game |
When I started working in web security fifteen years ago, web development looked very different. The few non-static web applications were built using a waterfall process and shipped quarterly at best, making it possible to add security audits before every release; applications were deployed exclusively on in-house servers, allowing Info Sec to inspect their configuration and setup; and the few third-party components used came from a small set of well-known and trusted providers. And yet, even with these favourable conditions, security teams were quickly overwhelmed and called for developers to build security in.
If the web security game was hard to win before, it’s doomed to fail now. In today’s web development, every other page is an application, accepting inputs and private data from users; software is built continuously, designed to eliminate manual gates, including security gates; infrastructure is code, with servers spawned with little effort and even less security scrutiny; and most of the code in a typical application is third-party code, pulled in through open source repositories with rarely a glance at who provided them.
Security teams, when they exist at all, cannot solve this problem. They are vastly outnumbered by developers, and cannot keep up with the application’s pace of change. For us to have a shot at making the web secure, we must bring security into the core. We need to give it no less attention than that we give browser compatibility, mobile design or web page load times. More broadly, we should see security as an aspect of quality, expecting both ourselves and our peers to address it, and taking pride when we do it well.
Where To Start?
Embracing security isn’t something you do overnight.
A good place to start is by reviewing things you’re already doing – and trying to make them more secure. Here are three concrete steps you can take to get going.
HTTPS
Threats begin when your system interacts with the outside world, which often means HTTP. As is, HTTP is painfully insecure, allowing attackers to easily steal and manipulate data going to or from the server. HTTPS adds a layer of crypto that ensures the parties know who they’re talking to, and that the information exchanged can be neither modified nor sniffed.
HTTPS is relevant to any site. If your non-HTTPS site holds opinions, reading it may get your users in trouble with employers or governments. If your users believe what you say, attackers can modify your non-HTTPS to take advantage of and abuse that trust. If you want to use new browser technologies like HTTP2 and service workers, your site will need to be HTTPS. And if you want to be discovered on the web, using HTTPS can help your Google ranking. For more details on why I think you should make the switch to HTTPS, check out this post, these slides and this video.
Using HTTPS is becoming easier and cheaper. Here are a few free tools that can help:
Get free and easy HTTPS delivery from Cloudflare (be sure to use “Full SSL”!)
Get a free and automation-friendly certificate from Let’s Encrypt (now in open beta).
Test how well your HTTPS is set up using SSLTest.
Other vendors and platforms are rapidly simplifying and reducing the cost of their HTTPS offering, as demand and importance grows.
Two-Factor Authentication
The most sensitive data is usually stored behind a login, and the authentication process is the primary gate in front of this data. Making this process secure has many aspects, including using HTTPS when accepting credentials, having a strong password policy, never storing the password, and more.
All of these are important, but the best single step to boost your authentication security is to introduce two-factor authentication (2FA). Adding 2FA usually means prompting users for an additional one-time code when logging in, which they get via SMS or a mobile app (e.g. Google Authenticator). This code is short-lived and is extremely hard for a remote attacker to guess, thus vastly reducing the risk a leaked or easily guessed password presents.
The typical algorithm for 2FA is based on an IETF standard called the time-based one-time password (TOTP) algorithm, and it isn’t that hard to implement. Joel Franusic wrote a great post on implementing 2FA; modules like speakeasy make it even easier; and you can swap SMS with Google Authenticator or your own app if you prefer. If you don’t want to build 2FA support yourself, you can purchase two/multi-factor authentication services from vendors such as DuoSecurity, Auth0, Clef, Hypr and others.
If implementing 2FA still feels like too much work, you can also choose to offload your entire authentication process to an OAuth-based federated login. Many companies offer this today, including Facebook, Google, Twitter, GitHub and others. These bigger players tend to do authentication well and support 2FA, but you should consider what data you’re sharing with them in the process.
Tracking Known Vulnerabilities
Most of the code in a modern application was actually written by third parties, and pulled into your app as frameworks, modules and libraries. While using these components makes us much more productive, along with their functionality we also adopt their security flaws. To make things worse, some of these flaws are well-known vulnerabilities, making it easy for hackers to take advantage of them in an attack.
This is a real problem and happens on pretty much every platform. Do you develop in Java? In 2014, over 6% of Java modules downloaded from Maven had a known severe security issue, the typical Java applications containing 24 flaws. Are you coding in Node.js? Roughly 14% of npm packages carry a known vulnerability, and over 60% of dev shops find vulnerabilities in their code. 30% of Docker Hub containers include a high priority known security hole, and 60% of the top 100,000 websites use client-side libraries with known security gaps.
To find known security issues, take stock of your dependencies and match them against language-specific lists such as Snyk’s vulnerability DB for Node.js, rubysec for Ruby, victims-db for Python and OWASP’s Dependency Check for Java. Once found, you can fix most issues by upgrading the component in question, though that may be tricky for indirect dependencies.
This process is still way too painful, which means most teams don’t do it. The Snyk team and I are hoping to change that by making it as easy as possible to find, fix and monitor known vulnerabilities in your dependencies. Snyk’s wizard will help you find and fix these issues through guided upgrades and patches, and adding Snyk’s test to your continuous integration and deployment (CI/CD) will help you stay secure as your code evolves.
Note that newly disclosed vulnerabilities usually impact old code – the one you’re running in production. This means you have to stay alert when new vulnerabilities are disclosed, so you can fix them before attackers can exploit them. You can do so by subscribing to vulnerability lists like US-CERT, OSVDB and NVD. Snyk’s monitor will proactively let you know about new disclosures relevant to your code, but only for Node.js for now – you can register to get updated when we expand.
Securing Yourself
In addition to making your application secure, you should make the contributors to that application secure – including you. Earlier this year we’ve seen attackers target mobile app developers with a malicious Xcode. The real target, however, wasn’t these developers, but rather the users of the apps they create. That you create. Securing your own work environment is a key part of keeping your apps secure, and your users from being compromised.
There’s no single step that will make you fully secure, but here are a few steps that can make a big impact:
Use 2FA on all the services related to the application, notably source control (e.g. GitHub), cloud platform (e.g. AWS), CI/CD, CDN, DNS provider and domain registrar. If an attacker compromises any one of those, they could modify or replace your entire application. I’d recommend using 2FA on all your personal services too.
Use a password manager (e.g. 1Password, LastPass) to ensure you have a separate and complex password for each service. Some of these services will get hacked, and passwords will leak. When that happens, don’t let the attackers access your other systems too.
Secure your workstation. Be careful what you download, lock your screen when you walk away, change default passwords on services you install, run antivirus software, etc. Malware on your machine can translate to malware in your applications.
Be very wary of phishing. Smart attackers use ‘spear phishing’ techniques to gain access to specific systems, and can trick even security savvy users. There are even phishing scams targeting users with 2FA. Be alert to phishy emails.
Don’t install things through curl <somewhere-on-the-web> | sudo bash, especially if the URL is on GitHub, meaning someone else controls it. Don’t do it on your machines, and definitely don’t do it in your CI/CD systems. Seriously.
Staying secure should be important to you personally, but it’s doubly important when you have privileged access to an application. Such access makes you a way to reach many more users, and therefore a more compelling target for bad actors.
A Culture of Security
Using HTTPS, enabling two-factor authentication and fixing known vulnerabilities are significant steps in building security at your core. As you implement them, remember that these are just a few steps in a longer journey.
The end goal is to embrace security as an aspect of quality, and accept we all share the responsibility of keeping ourselves – and our users – safe. |
2015 |
Guy Podjarny |
guypodjarny |
2015-12-11T00:00:00+00:00 |
https://24ways.org/2015/upping-your-web-security-game/ |
code |
| 292 |
Watch Your Language! |
I’m bilingual. My first language is French. I learned English in my early 20s. Learning a new language later in life meant that I was able to observe my thought processes changing over time. It made me realize that some concepts can’t be expressed in some languages, while other languages express these concepts with ease.
It also helped me understand the way we label languages. English: business. French: romance. Here’s an example of how words, or the absence thereof, can affect the way we think:
In French we love everything. There’s no straightforward way to say we like something, so we just end up loving everything. I love my sisters, I love broccoli, I love programming, I love my partner, I love doing laundry (this is a lie), I love my mom (this is not a lie). I love, I love, I love. It’s no wonder French is considered romantic. When I first learned English I used the word love rather than like because I hadn’t grasped the difference. Needless to say, I’ve scared away plenty of first dates!
Learning another language made me realize the limitations of my native language and revealed concepts I didn’t know existed. Without the nuances a given language provides, we fail to express what we really think. The absence of words in our vocabulary gets in the way of effectively communicating and considering ideas.
When I lived in Montréal, most people in my circle spoke both French and English. I could switch between them when I could more easily express an idea in one language or the other. I liked (or should I say loved?) those conversations. They were meaningful. They were efficient.
I’m quadrilingual. I code in Ruby, HTML/CSS, JavaScript, Python. In the past couple of years I have been lucky enough to write code in these languages at a massive scale. In learning Ruby, much like learning English, I discovered the strengths and limitations of not only the languages I knew but the language I was learning. It taught me to choose the right tool for the job.
When I started working at Shopify, making a change to a view involved copy/pasting HTML and ERB from one view to another. The CSS was roughly structured into modules, but those modules were not responsive to different screen sizes. Our HTML was complete mayhem, and we didn’t consider accessibility. All this made editing views a laborious process.
Grep. Replace all. Test. Ship it. Repeat.
This wasn’t sustainable at Shopify’s scale, so the newly-formed front end team was given two missions:
Make the app responsive (AKA Let’s Make This Thing Responsive ASAP)
Make the view layer scalable and maintainable (AKA Let’s Build a Pattern Library… in Ruby)
Let’s make this thing responsive ASAP
The year was 2015. The Shopify admin wasn’t mobile friendly. Our browser support was set to IE10. We had the wind in our sails. We wanted to achieve complete responsiveness in the shortest amount of time. Our answer: container queries.
It seemed like the obvious decision at the time. We would be able to set rules for each component in isolation and the component would know how to lay itself out on the page regardless of where it was rendered. It would save us a ton of development time since we wouldn’t need to change our markup, it would scale well, and we would achieve complete component autonomy by not having to worry about page layout. By siloing our components, we were going to unlock the ultimate goal of componentization, cutting the tie to external dependencies. We were cool.
Writing the JavaScript handling container queries was my first contribution to Shopify. It was a satisfying project to work on. We could drop our components in anywhere and they would magically look good. It took us less than a couple weeks to push this to production and make our app mostly responsive.
But with time, it became increasingly obvious that this was not as performant as we had hoped. It wasn’t performant at all. Components would jarringly jump around the page before settling in on first paint.
It was only when we started using the flex-wrap: wrap CSS property to build new components that we realized we were not using the right language for the job. So we swapped out JavaScript container queries for CSS flex-wrapping. Even though flex wasn’t yet as powerful as we wanted it to be, it was still a good compromise. Our components stayed independent of the window size but took much less time to render. Best of all: they used CSS instead of relying on JavaScript for layout.
In other words: we were using the wrong language to express our layout to the browser, when another language could do it much more simply and elegantly.
Let’s build a pattern library… in Ruby
In order to make our view layer maintainable, we chose to build a comprehensive library of helpers. This library would generate our markup from a single source of truth, allowing us to make changes system-wide, in one place. No. More. Grepping.
When I joined Shopify it was a Rails shop freshly wounded by a JavaScript framework (See: Batman.js). JavaScript was like Voldemort, the language that could not be named. Because of this baggage, the only way for us to build a pattern library that would get buyin from our developers was to use Rails view helpers. And for many reasons using Ruby was the right choice for us. The time spent ramping developers up on the new UI Components would be negligible since the Ruby API felt familiar. The transition would be simple since we didn’t have to introduce any new technology to the stack. The components would be fast since they would be rendered on the server. We had a plan.
We put in place a set of Rails tools to make it easy to build components, then wrote a bunch of sweet, sweet components using our shiny new tools. To document our design, content and front end patterns we put together an interactive styleguide to demonstrate how every component works. Our research and development department loved it (and still do)! We continue to roll out new components, and generally the project has been successful, though it has had its drawbacks.
Since the Shopify admin is mostly made up of a huge number of forms, most of the content is static. For this reason, using server-rendered components didn’t seem like a problem at the time. With new app features increasing the amount of DOM manipulation needed on the client side, our early design decisions mean making requests to the server for each re-paint. This isn’t going to cut it.
I don’t know the end of this story, because we haven’t written it yet. We’ve been exploring alternatives to our current system to facilitate the rendering of our components on the client, including React, Vue.js, and Web Components, but we haven’t determined the winner yet. Only time (and data gathering) will tell.
Ruby is great but it doesn’t speak the browser’s language efficiently. It was not the right language for the job.
Learning a new spoken language has had an impact on how I write code. It has taught me that you don’t know what you don’t know until you have the language to express it. Understanding the strengths and limitations of any programming language is fundamental to making good design decisions. At the end of the day, you make the best choices with the information you have. But if you still feel like you’re unable to express your thoughts to the fullest with what you know, it might be time to learn a new language. |
2016 |
Annie-Claude Côté |
annieclaudecote |
2016-12-10T00:00:00+00:00 |
https://24ways.org/2016/watch-your-language/ |
code |
| 193 |
Web Content Accessibility Guidelines—for People Who Haven't Read Them |
I’ve been a huge fan of the Web Content Accessibility Guidelines 2.0 since the World Wide Web Consortium (W3C) published them, nine years ago. I’ve found them practical and future-proof, and I’ve found that they can save a huge amount of time for designers and developers. You can apply them to anything that you can open in a browser. My favourite part is when I use the guidelines to make a website accessible, and then attend user-testing and see someone with a disability easily using that website.
Today, the United Nations International Day of Persons with Disabilities, seems like a good time to re-read Laura Kalbag’s explanation of why we should bother with accessibility. That should motivate you to devour this article.
If you haven’t read the Web Content Accessibility Guidelines 2.0, you might find them a bit off-putting at first. The editors needed to create a single standard that countries around the world could refer to in legislation, and so some of the language in the guidelines reads like legalese. The editors also needed to future-proof the guidelines, and so some terminology—such as “time-based media” and “programmatically determined”—can sound ambiguous. The guidelines can seem lengthy, too: printing the guidelines, the Understanding WCAG 2.0 document, and the Techniques for WCAG 2.0 document would take 1,200 printed pages.
This festive season, let’s rip off that legalese and ambiguous terminology like wrapping paper, and see—in a single article—what gifts the Web Content Accessibility Guidelines 2.0 editors have bestowed upon us.
Can your users perceive the information on your website?
The first guideline has criteria that help you prevent your users from asking “What the **** is this thing here supposed to be?”
1.1.1 Text is the most accessible format for information. Screen readers—such as the “VoiceOver” setting on your iPhone or the “TalkBack” app on your Android phone—understand text better than any other format. The same applies for other assistive technology, such as translation apps and Braille displays. So, if you have anything on your webpage that’s not text, you must add some text that gives your user the same information. You probably know how to do this already; for example:
for images in webpages, put some alternative text in an alt attribute to tell your user what the image conveys to the user;
for photos in tweets, add a description to make the images accessible;
for Instagram posts, write a caption that conveys the photo’s information.
The alternative text should allow the user to get the same information as someone who can see the image. For websites that have too many images for someone to add alternative text to, consider how machine learning and Dynamically Generated Alt Text might—might—be appropriate.
You can probably think of a few exceptions where providing text to describe an image might not make sense. Remember I described these guidelines as “practical”? They cover all those exceptions:
User interface controls such as buttons and text inputs must have names or labels to tell your user what they do.
If your webpage has video or audio (more about these later on!), you must—at least—have text to tell the user what they are.
Maybe your webpage has a test where your user has to answer a question about an image or some audio, and alternative text would give away the answer. In that case, just describe the test in text so your users know what it is.
If your webpage features a work of art, tell your user the experience it evokes.
If you have to include a Captcha on your webpage—and please avoid Captchas if at all possible, because some users cannot get past them—you must include text to tell your user what it is, and make sure that it doesn’t rely on only one sense, such as vision.
If you’ve included something just as decoration, you must make sure that your user’s assistive technology can ignore it. Again, you probably know how to do this. For example, you could use CSS instead of HTML to include decorative images, or you could add an empty alt attribute to the img element. (Please avoid that recent trend where developers add empty alt attributes to all images in a webpage just to make the HTML validate. You’re better than that.)
(Notice that the guidelines allow you to choose how to conform to them, with whatever technology you choose. To make your website conform to a guideline, you can either choose one of the techniques for WCAG 2.0 for that guideline or come up with your own. Choosing a tried-and-tested technique usually saves time!)
1.2.1 If your website includes a podcast episode, speech, lecture, or any other recorded audio without video, you must include a transcription or some other text to give your user the same information. In a lot of cases, you might find this easier than you expect: professional transcription services can prove relatively inexpensive and fast, and sometimes a speaker or lecturer can provide the speech or lecture notes that they read out word-for-word. Just make sure that all your users can get the same information and the same results, whether they can hear the audio or not. For example, David Smith and Marco Arment always publish episode transcripts for their Under the Radar podcast.
Similarly, if your website includes recorded video without audio—such as an animation or a promotional video—you must either use text to detail what happens in the video or include an audio version. Again, this might work out easier then you perhaps fear: for example, you could check to see whether the animation started life as a list of instructions, or whether the promotional video conveys the same information as the “About Us” webpage. You want to make sure that all your users can get the same information and the same results, whether they can see that video or not.
1.2.2 If your website includes recorded videos with audio, you must add captions to those videos for users who can’t hear the audio. Professional transcription services can provide you with time-stamped text in caption formats that YouTube supports, such as .srt and .sbv. You can upload those to YouTube, so captions appear on your videos there. YouTube can auto-generate captions, but the quality varies from impressively accurate to comically inaccurate. If you have a text version of what the people in the video said—such as the speech that a politician read or the bedtime story that an actor read—you can create a transcript file in .txt format, without timestamps. YouTube then creates captions for your video by synchronising that text to the audio in the video. If you host your own videos, you can ask a professional transcription service to give you .vtt files that you can add to a video element’s track element—or you can handcraft your own. (A quick aside: if your website has more videos than you can caption in a reasonable amount of time, prioritise the most popular videos, the most important videos, and the videos most relevant to people with disabilities. Then make sure your users know how to ask you to caption other videos as they encounter them.)
1.2.3 If your website has recorded videos that have audio, you must add an “audio description” narration to the video to describe important visual details, or add text to the webpage to detail what happens in the video for users who cannot see the videos. (I like to add audio files from videos to my Huffduffer account so that I can listen to them while commuting.) Maybe your home page has a video where someone says, “I’d like to explain our new TPS reports” while “Bill Lumbergh, division Vice President of Initech” appears on the bottom of the screen. In that case, you should add an audio description to the video that announces “Bill Lumbergh, division Vice President of Initech”, just before Bill starts speaking. As always, you can make life easier for yourself by considering all of your users, before the event: in this example, you could ask the speaker to begin by saying, “I’m Bill Lumbergh, division Vice President of Initech, and I’d like to explain our new TPS reports”—so you won’t need to spend time adding an audio description afterwards.
1.2.4 If your website has live videos that have some audio, you should get a stenographer to provide real-time captions that you can include with the video. I’ll be honest: this can prove tricky nowadays. The Web Content Accessibility Guidelines 2.0 predate YouTube Live, Instagram live Stories, Periscope, and other such services. If your organisation creates a lot of live videos, you might not have enough resources to provide real-time captions for each one. In that case, if you know the contents of the audio beforehand, publish the contents during the live video—or failing that, publish a transcription as soon as possible.
1.2.5 Remember what I said about the recorded videos that have audio? If you can choose to either add an audio description or add text to the webpage to detail what happens in the video, you should go with the audio description.
1.2.6 If your website has recorded videos that include audio information, you could provide a sign language version of the audio information; some people understand sign language better than written language. (You don’t need to caption a video of a sign language version of audio information.)
1.2.7 If your website has recorded videos that have audio, and you need to add an audio description, but the audio doesn’t have enough pauses for you to add an “audio description” narration, you could provide a separate version of that video where you have added pauses to fit the audio description into.
1.2.8 Let’s go back to the recorded videos that have audio once more! You could add text to the webpage to detail what happens in the video, so that people who can neither read captions nor hear dialogue and audio description can use braille displays to understand your video.
1.2.9 If your website has live audio, you could get a stenographer to provide real-time captions. Again, if you know the contents of the audio beforehand, publish the contents during the live audio or publish a transcription as soon as possible.
(Congratulations on making it this far! I know that seems like a lot to remember, but keep in mind that we’ve covered a complex area: helping your users to understand multimedia information that they can’t see and/or hear. Grab a mince pie to celebrate, and let’s keep going.)
1.3.1 You must mark up your website’s content so that your user’s browser, and any assistive technology they use, can understand the hierarchy of the information and how each piece of information relates to the rest. Once again, you probably know how to do this: use the most appropriate HTML element for each piece of information. Mark up headings, lists, buttons, radio buttons, checkboxes, and links with the most appropriate HTML element. If you’re looking for something to do to keep you busy this Christmas, scroll through the list of the elements of HTML. Do you notice any elements that you didn’t know, or that you’ve never used? Do you notice any elements that you could use on your current projects, to mark up the content more accurately? Also, revise HTML table advanced features and accessibility, how to structure an HTML form, and how to use the native form widgets—you might be surprised at how much you can do with just HTML! Once you’ve mastered those, you can make your website much more usable for your all of your users.
1.3.2 If your webpage includes information that your user has to read in a certain order, you must make sure that their browser and assistive technology can present the information in that order. Don’t rely on CSS or whitespace to create that order visually. Check that the order of the information makes sense when CSS and whitespace aren’t formatting it. Also, try using the Tab key to move the focus through the links and form widgets on your webpage. Does the focus go where you expect it to? Keep this in mind when using order in CSS Grid or Flexbox.
1.3.3 You must not presume that your users can identify sensory characteristics of things on your webpage. Some users can’t tell what you’ve positioned where on the screen. For example, instead of asking your users to “Choose one of the options on the left”, you could ask them to “Choose one of our new products” and link to that section of the webpage.
1.4.1 You must not rely on colour as the only way to convey something to your users. Some of your users can’t see, and some of your users can’t distinguish between colours. For example, if your webpage uses green to highlight the products that your shop has in stock, you could add some text to identify those products, or you could group them under a sub-heading.
1.4.2 If your webpage automatically plays a sound for more than 3 seconds, you must make sure your users can stop the sound or change its volume. Don’t rely on your user turning down the volume on their computer; some users need to hear the screen reader on their computer, and some users just want to keep listening to whatever they were listening before your webpage interrupted them!
1.4.3 You should make sure that your text contrasts enough with its background, so that your users can read it. Bookmark Lea Verou’s Contrast Ratio calculator now. You can enter the text colour and background colour as named colours, or as RGB, RGBa, HSL, or HSLa values. You should make sure that:
normal text that set at 24px or larger has a ratio of at least 3:1;
bold text that set at 18.75px or larger has a ratio of at least 3:1;
all other text has a ratio of at least 4½:1.
You don’t have to do this for disabled form controls, decorative stuff, or logos—but you could!
1.4.4 You should make sure your users can resize the text on your website up to 200% without using their assistive technology—and still access all your content and functionality. You don’t have to do this for subtitles or images of text.
1.4.5 You should avoid using images of text and just use text instead. In 1998, Jeffrey Veen’s first Hot Design Tip said, “Text is text. Graphics are graphics. Don’t confuse them.” Now that you can apply powerful CSS text-styling properties, use CSS Grid to precisely position text, and choose from thousands of web fonts (Jeffrey co-founded Typekit to help with this), you pretty much never need to use images of text. The guidelines say you can use images of text if you let your users specify the font, size, colour, and background of the text in the image of text—but I’ve never seen that on a real website. Also, this doesn’t apply to logos.
1.4.6 Let’s go back to colour contrast for a second. You could make your text contrast even more with its background, so that even more of your users can read it. To do that, use Lea Verou’s Contrast Ratio calculator to make sure that:
normal text that is 24px or larger has a ratio of at least 4½:1;
bold text that 18.75px or larger has a ratio of at least 4½:1;
all other text has a ratio of at least 7:1.
1.4.7 If your website has recorded speech, you could make sure there are no background sounds, or that your users can turn off any background sounds. If that’s not possible, you could make sure that any background sounds that last longer than a couple of seconds are at least four times quieter than the speech. This doesn’t apply to audio Captchas, audio logos, singing, or rapping. (Yes, these guidelines mention rapping!)
1.4.8 You could make sure that your users can reformat blocks of text on your website so they can read them better. To do this, make sure that your users can:
specify the colours of the text and the background, and
make the blocks of text less than 80-characters wide, and
align text to the left (or right for right-to-left languages), and
set the line height to 150%, and
set the vertical distance between paragraphs to 1½ times the line height of the text, and
resize the text (without using their assistive technology) up to 200% and still not have to scroll horizontally to read it.
By the way, when you specify a colour for text, always specify a colour for its background too. Don’t rely on default background colours!
1.4.9 Let’s return to images of text for a second. You could make sure that you use them only for decoration and logos.
Can users operate the controls and links on your website?
The second guideline has criteria that help you prevent your users from asking, “How the **** does this thing work?”
2.1.1 You must make sure that you users can carry out all of your website’s activities with just their keyboard, without time limits for pressing keys. (This doesn’t apply to drawing or anything else that requires a pointing device such as a mouse.) Again, if you use the most appropriate HTML element for each piece of information and for each form element, this should prove easy.
2.1.2 You must make sure that when the user uses the keyboard to focus on some part of your website, they can then move the focus to some other part of your webpage without needing to use a mouse or touch the screen. If your website needs them to do something complex before they can move the focus elsewhere, explain that to your user. These “keyboard traps” have become rare, but beware of forms that move focus from one text box to another as soon as they receive the correct number of characters.
2.1.3 Let’s revisit making sure that you users can carry out all of your website’s activities with just their keyboard, without time limits for pressing keys. You could make sure that your user can do absolutely everything on your website with just the keyboard.
2.2.1 Sometimes people need more time than you might expect to complete a task on your website. If any part of your website imposes a time limit on a task, you must do at least one of these:
let your users turn off the time limit before they encounter it; or
let your users increase the time limit to at least 10 times the default time limit before they encounter it; or
warn your users before the time limit expires and give them at least 20 seconds to extend it, and let them extend it at least 10 times.
Remember: these guidelines are practical. They allow you to enforce time limits for real-time events such as auctions and ticket sales, where increasing or extending time limits wouldn’t make sense. Also, the guidelines allow you to enforce a maximum time limit of 20 hours. The editors chose 20 hours because people need to go to sleep at some stage. See? Practical!
2.2.2 In my experience, this criterion remains the least well-known—even though some users can only use websites that conform to it. If your website presents content alongside other content that can distract users by automatically moving, blinking, scrolling, or updating, you must make sure that your users can:
pause, stop, or hide the other content if it’s not essential and lasts more than 5 seconds; and
pause, stop, hide, or control the frequency of the other content if it automatically updates.
It’s OK if your users miss live information such as stock price updates or football scores; you can’t do anything about that! Also, this doesn’t apply to animations such as progress bars that you put on a website to let all users know that the webpage isn’t frozen.
(If this one sounds complex, just add a pause button to anything that might distract your users.)
2.2.3 Let’s go back to time limits on tasks on your website. You could make your website even easier to use by removing all time limits except those on real-time events such as auctions and ticket sales. That would mean your user wouldn’t need to interact with a timer at all.
2.2.4 You could let your users turn off all interruptions—server updates, promotions, and so on—apart from any emergency information.
2.2.5 This is possibly my favourite of these criteria! After your website logs your user out, you could make sure that when they log in again, they can continue from where they were without having lost any information. Do that, and you’ll be on everyone’s Nice List this Christmas.
2.3.1 You must make sure that nothing flashes more than three times a second on your website, unless you can make sure that the flashes remain below the acceptable general flash and red flash thresholds…
2.3.2 …or you could just make sure that nothing flashes more than three times per second on your website. This is usually an easier goal.
2.4.1 You must make sure that your users can jump past any blocks of content, such as navigation menus, that are repeated throughout your website. You know the drill here: using HTML’s sectioning elements such as header, nav, main, aside, and footer allows users with assistive technology to go straight to the content they need, and adding “Skip Navigation” links allows everyone to get to your main content faster.
2.4.2 You must add a proper title to describe each webpage’s topic. Your webpage won’t even validate without a title element, so make it a useful one.
2.4.3 If your users can focus on links and native form widgets, you must make sure that they can focus on elements in an order that makes sense.
2.4.4 You must make sure that your users can understand the purpose of a link when they read:
the text of the link; or
the text of the paragraph, list item, table cell, or table header for the cell that contains the link; or
the heading above the link.
You don’t have to do that for games and quizzes.
2.4.5 You should give your users multiple ways to find any webpage within a set of webpages. Add site-wide search and a site map and you’re done!
This doesn’t apply for a webpage that is part of a series of actions (like a shopping cart and checkout flow) or to a webpage that is a result of a series of actions (like a webpage confirming that the user has bought what was in the shopping cart).
2.4.6 You should help your users to understand your content by providing:
headings that describe the topics of you content;
labels that describe the purpose of the native form widgets on the webpage.
2.4.7 You should make sure that users can see which element they have focussed on. Next time you use your website, try hitting the Tab key repeatedly. Does it visually highlight each item as it moves focus to it? If it doesn’t, search your CSS to see whether you’ve applied outline: 0; to all elements—that’s usually the culprit. Use the :focus pseudo-element to define how elements should appear when they have focus.
2.4.8 You could help your user to understand where the current webpage is located within your website. Add “breadcrumb navigation” and/or a site map and you’re done.
2.4.9 You could make links even easier to understand, by making sure that your users can understand the purpose of a link when they read the text of the link. Again, you don’t have to do that for games and quizzes.
2.4.10 You could use headings to organise your content by topic.
Can users understand your content?
The third guideline has criteria that help you prevent your users from asking, “What the **** does this mean?”
3.1.1 Let’s start this section with the criterion that possibly takes the least time to implement; you must make sure that the user’s browser can identify the main language that your webpage’s content is written in. For a webpage that has mainly English content, use <html lang="en">.
3.1.2 You must specify when content in another language appears in your webpage, like so: <q>I wish you a <span lang="fr">Joyeux Noël</span>.</q>. You don’t have to do this for proper names, technical terms, or words that you can’t identify a language for. You also don’t have to do it for words from a different language that people consider part of the language around those words; for example, <q>Come to our Christmas rendezvous!</q> is OK.
3.1.3 You could make sure that your users can find out the meaning of any unusual words or phrases, including idioms like “stocking filler” or “Bah! Humbug!” and jargon such as “VoiceOver” and “TalkBack”. Provide a glossary or link to a dictionary.
3.1.4 You could make sure that your users can find out the meaning of any abbreviation. For example, VoiceOver pronounces “Xmas” as “Smas” instead of “Christmas”. Using the abbr element and linking to a glossary can help. (Interestingly, VoiceOver pronounces “abbr” as “abbreviation”!)
3.1.5 Do your users need to be able to read better than a typically educated nine-year-old, to read your content (apart from proper names and titles)? If so, you could provide a version that doesn’t require that level of reading ability, or you could provide images, videos, or audio to explain your content. (You don’t have to add captions or audio description to those videos.)
3.1.6 You could make sure that your users can access the pronunciation of any word in your content if that word’s meaning depends on its pronunciation. For example, the word “close” could have one of two meanings, depending on pronunciation, in a phrase such as, “Ready for Christmas? Close now!”
3.2.1 Some users need to focus on elements to access information about them. You must make sure that focusing on an element doesn’t trigger any major changes, such as opening a new window, focusing on another element, or submitting a form.
3.2.2 Webpages are easier for users when the controls do what they’re supposed to do. Unless you have warned your users about it, you must make sure that changing the value of a control such as a text box, checkbox, or drop-down list doesn’t trigger any major changes, such as opening a new window, focusing on another element, or submitting a form.
3.2.3 To help your users to find the content they want on each webpage, you should put your navigation elements in the same place on each webpage. (This doesn’t apply when your user has changed their preferences or when they use assistive technology to change how your content appears.)
3.2.4 When a set of webpages includes things that have the same functionality on different webpages, you should name those things consistently. For example, don’t use the word “Search” for the search box on one webpage and “Find” for the search box on another webpage within that set of webpages.
3.2.5 Let’s go back to major changes, such as a new window opening, another element taking focus, or a form being submitted. You could make sure that they only happen when users deliberately make them happen, or when you have warned users about them first. For example, you could give the user a button for updating some content instead of automatically updating that content. Also, if a link will open in a new window, you could add the words “opens in new window” to the link text.
3.3.1 Users make mistakes when filling in forms. Your website must identify each mistake to your user, and must describe the mistake to your users in text so that the user can fix it. One way to identify mistakes reliably to your users is to set the aria-invalid attribute to true in the element that has a mistake. That makes sure that users with assistive technology will be alerted about the mistake. Of course, you can then use the [aria-invalid="true"] attribute selector in your CSS to visually highlight any such mistakes. Also, look into how certain attributes of the input element such as required, type, and list can help prevent and highlight mistakes.
3.3.2 You must include labels or instructions (and possibly examples) in your website’s forms, to help your users to avoid making mistakes.
3.3.3 When your user makes a mistake when filling in a form, your webpage should suggest ways to fix that mistake, if possible. This doesn’t apply in scenarios where those suggestions could affect the security of the content.
3.3.4 Whenever your user submits information that:
has legal or financial consequences; or
affects information that they have previously saved in your website; or
is part of a test
…you should make sure that they can:
undo it; or
correct any mistakes, after your webpage checks their information; or
review, confirm, and correct the information before they finally submit it.
3.3.5 You could help prevent your users from making mistakes by providing obvious, specific help, such as examples, animations, spell-checking, or extra instructions.
3.3.6 Whenever your user submits any information, you could make sure that they can:
undo it; or
correct any mistakes, after your webpage checks their information; or
review, confirm, and correct the information before they finally submit it.
Have you made your website robust enough to work on your users’ browsers and assistive technologies?
The fourth and final guideline has criteria that help you prevent your users from asking, “Why the **** doesn’t this work on my device?”
4.1.1 You must make sure that your website works as well as possible with current and future browsers and assistive technology. Prioritise complying with web standards instead of relying on the capabilities of currently popular devices and browsers. Web developers didn’t expect their users to be unwrapping the Wii U Browser five years ago—who knows what browsers and assistive technologies our users will be unwrapping in five years’ time? Avoid hacks, and use the W3C Markup Validation Service to make sure that your HTML has no errors.
4.1.2 If you develop your own user interface components, you must make their name, role, state, properties, and values available to your user’s browsers and assistive technologies. That should make them almost as accessible as standard HTML elements such as links, buttons, and checkboxes.
“…and a partridge in a pear tree!”
…as that very long Christmas song goes. We’ve covered a lot in this article—because your users have a lot of different levels of ability. Hopefully this has demystified the Web Content Accessibility Guidelines 2.0 for you. Hopefully you spotted a few situations that could arise for users on your website, and you now know how to tackle them.
To start applying what we’ve covered, you might like to look at Sarah Horton and Whitney Quesenbery’s personas for Accessible UX. Discuss the personas, get into their heads, and think about which aspects of your website might cause problems for them. See if you can apply what we’ve covered today, to help users like them to do what they need to do on your website.
How to know when your website is perfectly accessible for everyone
LOL! There will never be a time when your website becomes perfectly accessible for everyone. Don’t aim for that. Instead, aim for regularly testing and making your website more accessible.
Web Content Accessibility Guidelines (WCAG) 2.1
The W3C hope to release the Web Content Accessibility Guidelines (WCAG) 2.1 as a “recommendation” (that’s what the W3C call something that we should start using) by the middle of next year. Ten years may seem like a long time to move from version 2.0 to version 2.1, but consider the scale of the task: the editors have to update the guidelines to cover all the new ways that people interact with new technologies, while keeping the guidelines backwards-compatible. Keep an eye out for 2.1!
You’ll go down in history
One last point: I’ve met a surprising number of web designers and developers who do great work to make their websites more accessible without ever telling their users about it. Some of your potential customers have possibly tried and failed to use your website in the past. They probably won’t try again unless you let them know that things have improved. A quick Twitter search for your website’s name alongside phrases like “assistive technology”, “doesn’t work”, or “#fail” can let you find frustrated users—so you can tell them about how you’re making your website more accessible. Start making your websites work better for everyone—and please, let everyone know. |
2017 |
Alan Dalton |
alandalton |
2017-12-03T00:00:00+00:00 |
https://24ways.org/2017/wcag-for-people-who-havent-read-them/ |
code |
| 233 |
Wrapping Things Nicely with HTML5 Local Storage |
HTML5 is here to turn the web from a web of hacks into a web of applications – and we are well on the way to this goal. The coming year will be totally and utterly awesome if you are excited about web technologies.
This year the HTML5 revolution started and there is no stopping it. For the first time all the browser vendors are rallying together to make a technology work. The new browser war is fought over implementation of the HTML5 standard and not over random additions. We live in exciting times.
Starting with a bang
As with every revolution there is a lot of noise with bangs and explosions, and that’s the stage we’re at right now. HTML5 showcases are often CSS3 showcases, web font playgrounds, or video and canvas examples.
This is great, as it gets people excited and it gives the media something to show. There is much more to HTML5, though. Let’s take a look at one of the less sexy, but amazingly useful features of HTML5 (it was in the HTML5 specs, but grew at such an alarming rate that it warranted its own spec): storing information on the client-side.
Why store data on the client-side?
Storing information in people’s browsers affords us a few options that every application should have:
You can retain the state of an application – when the user comes back after closing the browser, everything will be as she left it. That’s how ‘real’ applications work and this is how the web ones should, too.
You can cache data – if something doesn’t change then there is no point in loading it over the Internet if local access is so much faster
You can store user preferences – without needing to keep that data on your server at all.
In the past, storing local data wasn’t much fun.
The pain of hacky browser solutions
In the past, all we had were cookies. I don’t mean the yummy things you get with your coffee, endorsed by the blue, furry junkie in Sesame Street, but the other, digital ones. Cookies suck – it isn’t fun to have an unencrypted HTTP overhead on every server request for storing four kilobytes of data in a cryptic format. It was OK for 1994, but really neither an easy nor a beautiful solution for the task of storing data on the client.
Then came a plethora of solutions by different vendors – from Microsoft’s userdata to Flash’s LSO, and from Silverlight isolated storage to Google’s Gears. If you want to know just how many crazy and convoluted ways there are to store a bit of information, check out Samy’s evercookie.
Clearly, we needed an easier and standardised way of storing local data.
Keeping it simple – local storage
And, lo and behold, we have one. The local storage API (or session storage, with the only difference being that session data is lost when the window is closed) is ridiculously easy to use. All you do is call a few methods on the window.localStorage object – or even just set the properties directly using the square bracket notation:
if('localStorage' in window && window['localStorage'] !== null){
var store = window.localStorage;
// valid, API way
store.setItem(‘cow’,‘moo’);
console.log(
store.getItem(‘cow’)
); // => ‘moo’
// shorthand, breaks at keys with spaces
store.sheep = ‘baa’
console.log(
store.sheep
); // ‘baa’
// shorthand for all
store[‘dog’] = ‘bark’
console.log(
store[‘dog’]
); // => ‘bark’
}
Browser support is actually pretty good: Chrome 4+; Firefox 3.5+; IE8+; Opera 10.5+; Safari 4+; plus iPhone 2.0+; and Android 2.0+. That should cover most of your needs. Of course, you should check for support first (or use a wrapper library like YUI Storage Utility or YUI Storage Lite).
The data is stored on a per domain basis and you can store up to five megabytes of data in localStorage for each domain.
Strings attached
By default, localStorage only supports strings as storage formats. You can’t store results of JavaScript computations that are arrays or objects, and every number is stored as a string. This means that long, floating point numbers eat into the available memory much more quickly than if they were stored as numbers.
var cowdesc = "the cow is of the bovine ilk, "+
"one end is for the moo, the "+
"other for the milk";
var cowdef = {
ilk“bovine”,
legs,
udders,
purposes
front“moo”,
end“milk”
}
};
window.localStorage.setItem(‘describecow’,cowdesc);
console.log(
window.localStorage.getItem(‘describecow’)
); // => the cow is of the bovine…
window.localStorage.setItem(‘definecow’,cowdef);
console.log(
window.localStorage.getItem(‘definecow’)
); // => [object Object] = bad!
This limits what you can store quite heavily, which is why it makes sense to use JSON to encode and decode the data you store:
var cowdef = {
"ilk":"bovine",
"legs":4,
"udders":4,
"purposes":{
"front":"moo",
"end":"milk"
}
};
window.localStorage.setItem(‘describecow’,JSON.stringify(cowdef));
console.log(
JSON.parse(
window.localStorage.getItem(‘describecow’)
)
); // => Object { ilk=“bovine”, more…}
You can also come up with your own formatting solutions like CSV, or pipe | or tilde ~ separated formats, but JSON is very terse and has native browser support.
Some use case examples
The simplest use of localStorage is, of course, storing some data: the current state of a game; how far through a multi-form sign-up process a user is; and other things we traditionally stored in cookies. Using JSON, though, we can do cooler things.
Speeding up web service use and avoiding exceeding the quota
A lot of web services only allow you a certain amount of hits per hour or day, and can be very slow. By using localStorage with a time stamp, you can cache results of web services locally and only access them after a certain time to refresh the data.
I used this technique in my An Event Apart 10K entry, World Info, to only load the massive dataset of all the world information once, and allow for much faster subsequent visits to the site. The following screencast shows the difference:
For use with YQL (remember last year’s 24 ways entry?), I’ve built a small script called YQL localcache that wraps localStorage around the YQL data call. An example would be the following:
yqlcache.get({
yql: 'select * from flickr.photos.search where text="santa"',
id: 'myphotos',
cacheage: ( 60*60*1000 ),
callback: function(data) {
console.log(data);
}
});
This loads photos of Santa from Flickr and stores them for an hour in the key myphotos of localStorage. If you call the function at various times, you receive an object back with the YQL results in a data property and a type property which defines where the data came from – live is live data, cached means it comes from cache, and freshcache indicates that it was called for the first time and a new cache was primed. The cache will work for an hour (60×60×1,000 milliseconds) and then be refreshed. So, instead of hitting the YQL endpoint over and over again, you hit it once per hour.
Caching a full interface
Another use case I found was to retain the state of a whole interface of an application by caching the innerHTML once it has been rendered. I use this in the Yahoo Firehose search interface, and you can get the full story about local storage and how it is used in this screencast:
The stripped down code is incredibly simple (JavaScript with PHP embed):
// test for localStorage support
if(('localStorage' in window) && window['localStorage'] !== null){
var f = document.getElementById(‘mainform’);
// test with PHP if the form was sent (the submit button has the name “sent”)
// get the HTML of the form and cache it in the property “state”
localStorage.setItem(‘state’,f.innerHTML);
// if the form hasn’t been sent…
// check if a state property exists and write back the HTML cache
if(‘state’ in localStorage){
f.innerHTML = localStorage.getItem(‘state’);
}
}
Other ideas
In essence, you can use local storage every time you need to speed up access. For example, you could store image sprites in base-64 encoded datasets instead of loading them from a server. Or you could store CSS and JavaScript libraries on the client. Anything goes – have a play.
Issues with local and session storage
Of course, not all is rainbows and unicorns with the localStorage API. There are a few niggles that need ironing out. As with anything, this needs people to use the technology and raise issues. Here are some of the problems:
Inadequate information about storage quota – if you try to add more content to an already full store, you get a QUOTA_EXCEEDED_ERR and that’s it. There’s a great explanation and test suite for localStorage quota available.
Lack of automatically expiring storage – a feature that cookies came with. Pamela Fox has a solution (also available as a demo and source code)
Lack of encrypted storage – right now, everything is stored in readable strings in the browser.
Bigger, better, faster, more!
As cool as the local and session storage APIs are, they are not quite ready for extensive adoption – the storage limits might get in your way, and if you really want to go to town with accessing, filtering and sorting data, real databases are what you’ll need. And, as we live in a world of client-side development, people are moving from heavy server-side databases like MySQL to NoSQL environments.
On the web, there is also a lot of work going on, with Ian Hickson of Google proposing the Web SQL database, and Nikunj Mehta, Jonas Sicking (Mozilla), Eliot Graff (Microsoft) and Andrei Popescu (Google) taking the idea beyond simply replicating MySQL and instead offering Indexed DB as an even faster alternative.
On the mobile front, a really important feature is to be able to store data to use when you are offline (mobile coverage and roaming data plans anybody?) and you can use the Offline Webapps API for that.
As I mentioned at the beginning, we have a very exciting time ahead – let’s make this web work faster and more reliably by using what browsers offer us. For more on local storage, check out the chapter on Dive into HTML5. |
2010 |
Christian Heilmann |
chrisheilmann |
2010-12-06T00:00:00+00:00 |
https://24ways.org/2010/html5-local-storage/ |
code |
| 276 |
Your jQuery: Now With 67% Less Suck |
Fun fact: more websites are now using jQuery than Flash.
jQuery is an amazing tool that’s made JavaScript accessible to developers and designers of all levels of experience. However, as Spiderman taught us, “with great power comes great responsibility.” The unfortunate downside to jQuery is that while it makes it easy to write JavaScript, it makes it easy to write really really f*&#ing bad JavaScript. Scripts that slow down page load, unresponsive user interfaces, and spaghetti code knotted so deep that it should come with a bottle of whiskey for the next sucker developer that has to work on it.
This becomes more important for those of us who have yet to move into the magical fairy wonderland where none of our clients or users view our pages in Internet Explorer. The IE JavaScript engine moves at the speed of an advancing glacier compared to more modern browsers, so optimizing our code for performance takes on an even higher level of urgency.
Thankfully, there are a few very simple things anyone can add into their jQuery workflow that can clear up a lot of basic problems. When undertaking code reviews, three of the areas where I consistently see the biggest problems are: inefficient selectors; poor event delegation; and clunky DOM manipulation. We’ll tackle all three of these and hopefully you’ll walk away with some new jQuery batarangs to toss around in your next project.
Selector optimization
Selector speed: fast or slow?
Saying that the power behind jQuery comes from its ability to select DOM elements and act on them is like saying that Photoshop is a really good tool for selecting pixels on screen and making them change color – it’s a bit of a gross oversimplification, but the fact remains that jQuery gives us a ton of ways to choose which element or elements in a page we want to work with. However, a surprising number of web developers are unaware that all selectors are not created equal; in fact, it’s incredible just how drastic the performance difference can be between two selectors that, at first glance, appear nearly identical. For instance, consider these two ways of selecting all paragraph tags inside a <div> with an ID.
$("#id p");
$("#id").find("p");
Would it surprise you to learn that the second way can be more than twice as fast as the first? Knowing which selectors outperform others (and why) is a pretty key building block in making sure your code runs well and doesn’t frustrate your users waiting for things to happen.
There are many different ways to select elements using jQuery, but the most common ways can be basically broken down into five different methods. In order, roughly, from fastest to slowest, these are:
$("#id");
This is without a doubt the fastest selector jQuery provides because it maps directly to the native document.getElementbyId() JavaScript method. If possible, the selectors listed below should be prefaced with an ID selector in conjunction with jQuery’s .find() method to limit the scope of the page that has to be searched (as in the $("#id").find("p") example shown above).
$("p");, $("input");, $("form"); and so on
Selecting elements by tag name is also fast, since it maps directly to the native document.getElementsByTagname() method.
$(".class");
Selecting by class name is a little trickier. While still performing very well in modern browsers, it can cause some pretty significant slowdowns in IE8 and below. Why? IE9 was the first IE version to support the native document.getElementsByClassName() JavaScript method. Older browsers have to resort to using much slower DOM-scraping methods that can really impact performance.
$("[attribute=value]");
There is no native JavaScript method for this selector to use, so the only way that jQuery can perform the search is by crawling the entire DOM looking for matches. Modern browsers that support the querySelectorAll() method will perform better in certain cases (Opera, especially, runs these searches much faster than any other browser) but, generally speaking, this type of selector is Slowey McSlowersons.
$(":hidden");
Like attribute selectors, there is no native JavaScript method for this one to use. Pseudo-selectors can be painfully slow since the selector has to be run against every element in your search space. Again, modern browsers with querySelectorAll() will perform slightly better here, but try to avoid these if at all possible. If you must use one, try to limit the search space to a specific portion of the page: $("#list").find(":hidden");
But, hey, proof is in the performance testing, right? It just so happens that said proof is sitting right here. Be sure to notice the class selector numbers beside IE7 and 8 compared to other browsers and then wonder how the people on the IE team at Microsoft manage to sleep at night. Yikes.
Chaining
Almost all jQuery methods return a jQuery object. This means that when a method is run, its results are returned and you can continue executing more methods on them. Rather than writing out the same selector multiple times over, just making a selection once allows multiple actions to be run on it.
Without chaining
$("#object").addClass("active");
$("#object").css("color","#f0f");
$("#object").height(300);
With chaining
$("#object").addClass("active").css("color", "#f0f").height(300);
This has the dual effect of making your code shorter and faster. Chained methods will be slightly faster than multiple methods made on a cached selector, and both ways will be much faster than multiple methods made on non-cached selectors. Wait… “cached selector”? What is this new devilry?
Caching
Another easy way to speed up your code that seems to be a mystery to developers is the idea of caching your selectors. Think of how many times you end up writing the same selector over and over again in any project. Every $(".element") selector has to search the entire DOM each time, regardless of whether or not that selector had been previously run. Running the selection once and then storing the results in a variable means that the DOM only has to be searched once. Once the results of a selector have been cached, you can do anything with them.
First, run your search (here we’re selecting all of the <li> elements inside <ul id="blocks">):
var blocks = $("#blocks").find("li");
Now, you can use the blocks variable wherever you want without having to search the DOM every time.
$("#hideBlocks").click(function() {
blocks.fadeOut();
});
$("#showBlocks").click(function() {
blocks.fadeIn();
});
My advice? Any selector that gets run more than once should be cached. This jsperf test shows just how much faster a cached selector runs compared to a non-cached one (and even throws some chaining love in to boot).
Event delegation
Event listeners cost memory. In complex websites and apps it’s not uncommon to have a lot of event listeners floating around, and thankfully jQuery provides some really easy methods for handling event listeners efficiently through delegation.
In a bit of an extreme example, imagine a situation where a 10×10 cell table needs to have an event listener on each cell; let’s say that clicking on a cell adds or removes a class that defines the cell’s background color. A typical way that this might be written (and something I’ve often seen during code reviews) is like so:
$('table').find('td').click(function() {
$(this).toggleClass('active');
});
jQuery 1.7 has provided us with a new event listener method, .on(). It acts as a utility that wraps all of jQuery’s previous event listeners into one convenient method, and the way you write it determines how it behaves. To rewrite the above .click() example using .on(), we’d simply do the following:
$('table').find('td').on('click',function() {
$(this).toggleClass('active');
});
Simple enough, right? Sure, but the problem here is that we’re still binding one hundred event listeners to our page, one to each individual table cell. A far better way to do things is to create one event listener on the table itself that listens for events inside it. Since the majority of events bubble up the DOM tree, we can bind a single event listener to one element (in this case, the <table>) and wait for events to bubble up from its children. The way to do this using the .on() method requires only one change from our code above:
$('table').on('click','td',function() {
$(this).toggleClass('active');
});
All we’ve done is moved the td selector to an argument inside the .on() method. Providing a selector to .on() switches it into delegation mode, and the event is only fired for descendants of the bound element (table) that match the selector (td). With that one simple change, we’ve gone from having to bind one hundred event listeners to just one. You might think that the browser having to do one hundred times less work would be a good thing and you’d be completely right. The difference between the two examples above is staggering.
(Note that if your site is using a version of jQuery earlier than 1.7, you can accomplish the very same thing using the .delegate() method. The syntax of how you write the function differs slightly; if you’ve never used it before, it’s worth checking the API docs for that page to see how it works.)
DOM manipulation
jQuery makes it very easy to manipulate the DOM. It’s trivial to create new nodes, insert them, remove other ones, move things around, and so on. While the code to do this is simple to write, every time the DOM is manipulated, the browser has to repaint and reflow content which can be extremely costly. This is no more evident than in a long loop, whether it be a standard for() loop, while() loop, or jQuery $.each() loop.
In this case, let’s say we’ve just received an array full of image URLs from a database or Ajax call or wherever, and we want to put all of those images in an unordered list. Commonly, you’ll see code like this to pull this off:
var arr = [reallyLongArrayOfImageURLs];
$.each(arr, function(count, item) {
var newImg = '<li><img src="'+item+'"></li>';
$('#imgList').append(newImg);
});
There are a couple of problems with this. For one (which you should have already noticed if you’ve read the earlier part of this article), we’re making the $("#imgList") selection once for each iteration of our loop. The other problem here is that each time the loop iterates, it’s adding a new <li> to the DOM. Each of those insertions is going to be costly, and if our array is quite large then this could lead to a massive slowdown or even the dreaded ‘A script is causing this page to run slowly’ warning.
var arr = [reallyLongArrayOfImageURLs],
tmp = '';
$.each(arr, function(count, item) {
tmp += '<li><img src="'+item+'"></li>';
});
$('#imgList').append(tmp);
All we’ve done here is create a tmp variable that each <li> is added to as it’s created. Once our loop has finished iterating, that tmp variable will contain all of our list items in memory, and can be appended to our <ul> all in one go. Browsers work much faster when working with objects in memory rather than on screen, so this is a much faster, more CPU-cycle-friendly method of building a list.
Wrapping up
These are far from being the only ways to make your jQuery code run better, but they are among the simplest ones to implement. Though each individual change may only make a few milliseconds of difference, it doesn’t take long for those milliseconds to add up. Studies have shown that the human eye can discern delays of as few as 100ms, so simply making a few changes sprinkled throughout your code can very easily have a noticeable effect on how well your website or app performs. Do you have other jQuery optimization tips to share? Leave them in the comments and help make us all better.
Now go forth and make awesome! |
2011 |
Scott Kosman |
scottkosman |
2011-12-13T00:00:00+00:00 |
https://24ways.org/2011/your-jquery-now-with-less-suck/ |
code |
| 221 |
“Probably, Maybe, No”: The State of HTML5 Audio |
With the hype around HTML5 and CSS3 exceeding levels not seen since 2005’s Ajax era, it’s worth noting that the excitement comes with good reason: the two specifications render many years of feature hacks redundant by replacing them with native features. For fun, consider how many CSS2-based rounded corners hacks you’ve probably glossed over, looking for a magic solution. These days, with CSS3, the magic is border-radius (and perhaps some vendor prefixes) followed by a coffee break.
CSS3’s border-radius, box-shadow, text-shadow and gradients, and HTML5’s <canvas>, <audio> and <video> are some of the most anticipated features we’ll see put to creative (ab)use as adoption of the ‘new shiny’ grows. Developers jumping on the cutting edge are using subsets of these features to little detriment, in most cases. The more popular CSS features are design flourishes that can degrade nicely, but the current audio and video implementations in particular suffer from a number of annoyances.
The new shiny: how we got here
Sound involves one of the five senses, a key part of daily life for most – and yet it has been strangely absent from HTML and much of the web by default. From a simplistic perspective, it seems odd that HTML did not include support for the full multimedia experience earlier, despite the CD-ROM-based craze of the early 1990s. In truth, standards like HTML can take much longer to bake, but eventually deliver the promise of a lowered barrier to entry, consistent implementations and shiny new features now possible ‘for free’ just about everywhere.
<img> was introduced early and naturally to HTML, despite having some opponents at the time. Perhaps <audio> and <video> were avoided, given the added technical complexity of decoding various multi-frame formats, plus the hardware and bandwidth limitations of the era. Perhaps there were quarrels about choosing a standard format or – more simply – maybe these elements just weren’t considered to be applicable to the HTML-based web at the time. In any event, browser plugins from programs like RealPlayer and QuickTime eventually helped to fill the in-page audio/video gap, handling <object> and <embed> markup which pointed to .wav, .avi, .rm or .mov files. Suffice it to say, the experience was inconsistent at best and, on the standards side of the fence right now, so is HTML5 in terms of audio and video.
: the theory
As far as HTML goes, the code for <audio> is simple and logical. Just as with <img>, a src attribute specifies the file to load. Pretty straightforward – sounds easy, right?
<audio src="mysong.ogg" controls>
<!-- alternate content for unsupported case -->
Download <a href="mysong.ogg">mysong.ogg</a>;
</audio>
Ah, if only it were that simple. The first problem is that the OGG audio format, while ‘free’, is not supported by some browsers. Conversely, nor is MP3, despite being a de facto standard used in all kinds of desktop software (and hardware). In fact, as of November 2010, no single audio format is commonly supported across all major HTML5-enabled browsers.
What you end up writing, then, is something like this:
<audio controls>
<source src="mysong.mp3" />
<source src="mysong.ogg" />
<!-- alternate content for unsupported case, maybe Flash, etc. -->
Download <a href="mysong.ogg">mysong.ogg</a> or <a href="mysong.mp3">mysong.mp3</a>
</audio>
Keep in mind, this is only a ‘first class’ experience for the HTML5 case; also, for non-supported browsers, you may want to look at another inline player (object/embed, or a JavaScript plus Flash API) to have inline audio. You can imagine the added code complexity in the case of supporting ‘first class’ experiences for older browsers, too.
: the caveats
With <img>, you typically don’t have to worry about format support – it just works – and that’s part of what makes a standard wonderful. JPEG, PNG, BMP, GIF, even TIFF images all render just fine if for no better reason, perhaps, than being implemented during the ‘wild west’ days of the web. The situation with <audio> today reflects a very different – read: business-aware – environment in 2010. (Further subtext: There’s a lot of [potential] money involved.) Regrettably, this is a collision of free and commercial interests, where the casualty is ultimately the user. Second up in the casualty list is you, the developer, who has to write additional code around this fragmented support.
The HTML5 audio API as implemented in JavaScript has one of the most un-computer-like responses I’ve ever seen, and inspired the title of this post. Calling new Audio().canPlayType('audio/mp3'), which queries the system for format support according to a MIME type, is supposed to return one of “probably”, “maybe”, or “no”. Sometimes, you’ll just get a null or empty string, which is also fun. A “maybe” response does not guarantee that a format will be supported; sometimes audio/mp3 gives “maybe,” but then audio/mpeg; codecs="mp3" will give a more-solid “probably” response. This can vary by browser or platform, too, depending on native support – and finally, the user may also be able to install codecs, extending support to include other formats. (Are you excited yet?)
Damn you, warring formats!
New market and business opportunities go hand-in-hand with technology developments. What we have here is certainly not failure to communicate; rather, we have competing parties shouting loudly in public in attempts to influence mindshare towards a de facto standard for audio and video. Unfortunately, the current situation means that at least two formats are effectively required to serve the majority of users correctly.
As it currently stands, we have the free and open source software camp of OGG Vorbis/WebM and its proponents (notably, Mozilla, Google and Opera in terms of browser makers), up against the non-free, proprietary and ‘closed’ camp of MP3 and MPEG4/HE-AAC/H.264 – which is where you’ll find commitments from Apple and Microsoft, among others. Apple is likely in with H.264 for the long haul, given its use of the format for its iTunes music store and video offerings.
It is generally held that H.264 is a technically superior format in terms of file size versus quality, but it involves intellectual property and, in many use cases, requires licensing fees. To be fair, there is a business model with H.264 and much has been invested in its development, but this approach is not often the kind that wins over the web. On that front, OGG/WebM may eventually win for being a ‘free’ format that does not involve a licensing scheme.
Closed software and tools ideologically clash with the open nature of the web, which exists largely thanks to free and open technology. Because of philosophical and business reasons, support for audio and video is fragmented across browsers adopting HTML5 features. It does not help that a large amount of audio and video currently exists in non-free MP3 and MPEG-4 formats. Adoption of <audio> and <video> may be slowed, since it is more complex than <img> and may feel ‘broken’ to developers when edge cases are encountered. Furthermore, the HTML5 spec does not mandate a single required format. The end result is that, as a developer, you must currently provide at least both MP3 and OGG, for example, to serve most existing HTML5-based user agents.
Transitioning to
There will be some growing pains as developers start to pick up the new HTML5 shiny, while balancing the needs of current and older agents that don’t support either <audio> or the preferred format you may choose (for example, MP3). In either event, Flash or other plugins can be used as done traditionally within HTML4 documents to embed and play the relevant audio.
The SoundManager 2 page player demo in action.
Ideally, HTML5 audio should be used whenever possible with Flash as the backup option. A few JavaScript/Flash-based audio player projects exist which balance the two; in attempting to tackle this problem, I develop and maintain SoundManager 2, a JavaScript sound API which transparently uses HTML5 Audio() and, if needed, Flash for playing audio files. The internals can get somewhat ugly, but the transition between HTML4 and HTML5 is going to be just that – and even with HTML5, you will need some form of format fall-back in addition to graceful degradation.
It may be safest to fall back to MP3/MP4 formats for inline playback at this time, given wide support via Flash, some HTML5-based browsers and mobile devices. Considering the amount of MP3/MP4 media currently available, it is wiser to try these before falling through to a traditional file download process.
Early findings
Here is a brief list of behavioural notes, annoyances, bugs, quirks and general weirdness I have found while playing with HTML5-based audio at time of writing (November 2010):
Apple iPad/iPhone (iOS 4, iPad 3.2+)
Only one sound can be played at a time. If a second sound starts, the first is stopped.
No auto-play allowed. Sounds follow the pop-up window security model and can only be started from within a user event handler such as onclick/touch, and so on. Otherwise, playback attempts silently fail.
Once started, a sequence of sounds can be created or played via the ‘finish’ event of the previous sound (for example, advancing through a playlist without interaction after first track starts).
iPad, iOS 3.2: Occasional ‘infinite loop’ bug seen where audio does not complete and stop at a sound’s logical end – instead, it plays again from the beginning. Might be specific to example file format (HE-AAC) encoded from iTunes.
Apple Safari, OS X Snow Leopard 10.6.5
Critical bug: Safari 4 and 5 intermittently fail to load or play HTML5 audio on Snow Leopard due to bug(s) in QuickTime X and/or other underlying frameworks. Known Apple ‘radar’ bug: bugs.webkit.org #32159 (see also, test case.) Amusing side note: Safari on Windows is fine.
Apple Safari, Windows
Food for thought: if you download “Safari” alone on Windows, you will not get HTML5 audio/video support (tested in WinXP). You need to download “Safari + QuickTime” to get HTML5 audio/video support within Safari. (As far as I’m aware, Chrome, Firefox and Opera either include decoders or use system libraries accordingly. Presumably IE 9 will use OS-level APIs.)
General Quirks
Seeking and loading, ‘progress’ events, and calculating bytes loaded versus bytes total should not be expected to be linear, as users can arbitrarily seek within a sound. It appears that some support for HTTP ranges exists, which adds a bit of logic to UI code. Browsers seem to vary slightly in their current implementations of these features.
The onload event of a sound may be of little relevance, if non-linear loading is involved (see above note re: seeking).
Interestingly (perhaps I missed it), the current spec does not seem to specify a panning or left/right channel mix option.
The preload attribute values may vary slightly between browsers at this time.
Upcoming shiny: HTML5 Audio Data API
With access to audio data, you can incorporate waveform and spectrum elements that make your designs react to music.
The HTML5 audio spec does a good job covering the basics of playback, but did not initially get into manipulation or generation of audio on-the-fly, something Flash has had for a number of years now. What if JavaScript could create, monitor and change audio dynamically, like a sort of audio <canvas> element? With that kind of capability, many dynamic audio processing features become feasible and, when combined with other media, can make for some impressive demos.
What started as a small idea among a small group of audio and programming enthusiasts grew to inspire a W3C audio incubator group, and continued to establish the Mozilla Audio Data API. Contributors wrote a patch for Firefox which was reviewed and revised, and is now slated to be in the public release of Firefox 4. Some background and demos are also detailed in an article from the BBC R&D blog.
There are plenty of live demos to see, which give an impression of the new creative ideas this API enables. Many concepts are not new in themselves, but it is exciting to see this sort of thing happening within the native browser context.
Mozilla is not alone in this effort; the WebKit folks are also working on a JavaScriptAudioNode interface, which implements similar audio buffering and sample elements.
The future?
It is my hope that we’ll see a common format emerge in terms of support across the major browsers for both audio and video; otherwise, support will continue to be fragmented and mildly frustrating to develop for, and that can impede growth of the feature. It’s a big call, but if <img> had lacked a common format back in the wild west era, I doubt the web would have grown to where it is today.
Complaints and nitpicks aside, HTML5 brings excellent progress on the browser multimedia front, and the first signs of native support are a welcome improvement given all audio and video previously relied on plugins. There is good reason to be excited. While there is room for more, support could certainly be much worse – and as tends to happen with specifications, the implementations targeting them should improve over time.
Note: Thanks to Nate Koechley, who suggested the Audio().canPlayType() response be part of the article title. |
2010 |
Scott Schiller |
scottschiller |
2010-12-08T00:00:00+00:00 |
https://24ways.org/2010/the-state-of-html5-audio/ |
code |