Garrett talks through some handy HTML attributes: spellcheck, autofocus, autocapitalize, autocomplete, and autocorrect:
While they feel like small details, when we set these attributes on inputs, we streamline things for visitors while also guiding the browser on when it should just get out of the way.
I’ve been deep-diving into HTML web components over the past few weeks. I decided to refactor the JavaScript on The Session to use custom elements wherever it made sense.
I really enjoyed doing this, even though the end result for users is exactly the same as before. This was one of those refactors that was for me, and also for future me. The front-end codebase looks a lot more understandable and therefore maintainable.
Most of the JavaScript on The Session is good ol’ DOM scripting. Listen for events; when an event happens, make some update to some element. It’s the kind of stuff we might have used jQuery for in the past.
Chris invoked Betteridge’s law of headlines recently by asking Will Web Components replace React and Vue? I agree with his assessment. The reactivity you get with full-on frameworks isn’t something that web components offer. But I do think web components can replace jQuery and other approaches to scripting the DOM.
I’ve written about my preferred way to do DOM scripting: element.target.closest. One of the advantages to that approach is that even if the DOM gets updated—perhaps via Ajax—the event listening will still work.
Well, this is exactly the kind of thing that custom elements take care of for you. The connectedCallback method gets fired whenever an instance of the custom element is added to the document, regardless of whether that’s in the initial page load or later in an Ajax update.
So my client-side scripting style has updated over time:
event.target.closest.None of these progressions were particularly ground-breaking or allowed me to do anything I couldn’t do previously. But each progression improved the resilience and maintainability of my code.
Like Chris, I’m using web components to progressively enhance what’s already in the markup. In fact, looking at the code that Chris is sharing, I think we may be writing some very similar web components!
A few patterns have emerged for me…
Naming things is famously hard. Every time you make a new custom element you have to give it a name that includes a hyphen. I settled on the convention of using the first part of the name to echo the element being enhanced.
If I’m adding an enhancement to a button element, I’ll wrap it in a custom element that starts with button-. I’ve now got custom elements like button-geolocate, button-confirm, button-clipboard and so on.
Likewise if the custom element is enhancing a link, it will begin with a-. If it’s enhancing a form, it will begin with form-.
The name of the custom element tells me how it’s expected to be used. If I find myself wrapping a div with button-geolocate I shouldn’t be surprised when it doesn’t work.
You can use any attributes you want on a web component. You made up the name of the custom element and you can make up the names of the attributes too.
I’m a little nervous about this. What if HTML ends up with a new global attribute in the future that clashes with something I’ve invented? It’s unlikely but it still makes me wary.
So I use data- attributes. I’ve already got a hyphen in the name of my custom element, so it makes sense to have hyphens in my attributes too. And by using data- attributes, the browser gives me automatic reflection of the value in the dataset property.
Instead of getting a value with this.getAttribute('maximum') I get to use this.dataset.maximum. Nice and neat.
My favourite web components aren’t all-singing, all-dancing powerhouses. Rather they do one thing, often a very simple thing.
Here are some examples:
aria-collapsable for toggling the display of one element when you click on another.play-button for adding a play button to an audio or video element.ajax-form for sending a form via Ajax instead of a full page refresh.user-avatar for adding a tooltip to an image.table-saw for making tables responsive.All of those are HTML web components in that they extend your existing markup rather than JavaScript web components that are used to replace HTML. All of those are also unambitious by design. They each do one thing and one thing only.
But what if my web component needs to do two things?
I make two web components.
The beauty of custom elements is that they can be used just like regular HTML elements. And the beauty of HTML is that it’s composable.
What if you’ve got some text that you want to be a level-three heading and also a link? You don’t bemoan the lack of an element that does both things. You wrap an a element in an h3 element.
The same goes for custom elements. If I find myself adding multiple behaviours to a single custom element, I stop and ask myself if this should be multiple custom elements instead.
Take some of those button- elements I mentioned earlier. One of them copies text to the clipboard, button-clipboard. Another throws up a confirmation dialog to complete an action, button-confirm. Suppose I want users to confirm when they’re copying something to their clipboard (not a realistic example, I admit). I don’t have to create a new hybrid web component. Instead I wrap the button in the two existing custom elements.
Rather than having a few powerful web components, I like having lots of simple web components. The power comes with how they’re combined. Like Unix pipes. And it has the added benefit of stopping my code getting too complex and hard to understand.
Okay, so I’ve broken all of my behavioural enhancements down into single-responsibility web components. But what if one web component needs to have awareness of something that happens in another web component?
Here’s an example from The Session: the results page when you search for sessions in London.
There’s a map. That’s one web component. There’s a list of locations. That’s another web component. There are links for traversing backwards and forwards through the locations via Ajax. Those links are in web components too.
I want the map to update when the list of locations changes. Where should that logic live? How do I get the list of locations to communicate with the map?
When a list of locations is added to the document, it emits a custom event that bubbles all the way up. In fact, that’s all this component does.
You can call the event anything you want. It could be a newLocations event. That event is dispatched in the connectedCallback of the component.
Meanwhile in the map component, an event listener listens for any newLocations events on the document. When that event handler is triggered, the map updates.
The web component that lists locations has no idea that there’s a map on the same page. It doesn’t need to. It just needs to dispatch its event, no questions asked.
There’s nothing specific to web components here. Event-driven programming is a tried and tested approach. It’s just a little easier to do thanks to the connectedCallback method.
I’m documenting all this here as a snapshot of my current thinking on HTML web components when it comes to:
I may well end up changing my approach again in the future. For now though, these ideas are serving me well.
This is good advice:
Write alternative text as if you’re describing the image to a friend.
This is a little follow-up to my post about web components for date inputs.
If you try the demo on iOS it doesn’t work. There’s nothing stopping you selecting any date.
That’s nothing to do with the web components. It turns out that Safari on iOS doesn’t support min and max on date inputs. This is also true of any other browser on iOS because they’re all just Safari in a trenchcoat …for now.
I was surprised — input type="date" has been around for a long time now. I mean, it’s not the end of the world. You’d have to do validation on inputted dates on the server anyway, but it sure would be nice for the user experience of filling in forms.
Alas, it doesn’t look like this is something on the interop radar.
What really surprised me was looking at Can I Use. That shows Safari on iOS as fully supporting date inputs.
Maybe it’s just semantic nitpickery on my part but I would consider that the lack of support for the min and max attributes means that date inputs are partially supported.
Can I Use gets its data from here. I guess I need to study the governance rules and try to figure out how to submit a pull request to update the currently incorrect information.
This is an interesting idea from Scott—a templating language that doesn’t just replace variables with values, but keeps the original variable names in there too.
Not sure how I feel about using data- attributes for this though; as far as I know, they’re intended to be site-specific, not for cross-site solutions like this.
Huh! I did not know this. Good to know!
The slides from Hidde’s presentation at Paris Web—a great overview of using and misusing ARIA.
It gives me warm fuzzies to see an indie web building block like rel="me" getting coverage like this.
It’s been almost two years since I added audio playback on The Session. The interface is quite straightforward. For any tune setting, there’s a button that says “play audio”. When you press that button, audio plays and the button’s text changes to “pause audio.”
By updating the button’s text like this, I’m updating the button’s accessible name. In other situations, where the button text doesn’t change, you can indicate whether a button is active or not by toggling the aria-pressed attribute. I’ve been doing that on the “share” buttons that act as the interface for a progressive disclosure. The label on the button—“share”—doesn’t change when the button is pressed. For that kind of progressive disclosure pattern, the button also has an aria-controls and aria-expanded attribute.
From all the advice I’ve read about button states, you should either update the accessible name or change the aria-pressed attribute, but not both. That would lead to the confusing situation of having a button labelled “pause audio” as having a state of “pressed” when in fact the audio is playing.
That was all fine until I recently added some more functionality to The Session. As well as being able to play back audio, you can now adjust the tempo of the playback speed. The interface element for this is a slider, input type="range".
But this means that the “play audio” button now does two things. It plays the audio, but it also acts as a progressive disclosure control, revealing the tempo slider. The button is simultaneously a push button for playing and pausing music, and a toggle button for showing and hiding another interface element.
So should I be toggling the aria-pressed attribute now, even though the accessible name is changing? Or is it enough to have the relationship defined by aria-controls and the state defined by aria-expanded?
Based on past experience, my gut feeling is that I’m probably using too much ARIA. Maybe it’s an anti-pattern to use both aria-expanded and aria-pressed on a progressive disclosure control.
I’m kind of rubber-ducking here, and now that I’ve written down what I’m thinking, I’m pretty sure I’m going to remove the toggling of aria-pressed in any situation where I’m already toggling aria-expanded.
What I really need to do is enlist the help of actual screen reader users. There are a number of members of The Session who use screen readers. I should get in touch and see if the new functionality makes sense to them.
The capture attribute is pretty nifty—and I just love that you get so much power in a declarative way:
<input type="file" accept="image/*" capture="environment">
I really like the progressive enhancement approach that this little library uses—it’s basically the Hijax approach I was talking about back in the days of Bulletproof Ajax but all wrapped up into a neat package that you can use entirely via HTML attributes.
This is a very handy table of elements from Steve of where aria-label can be applied.
Like, for example, not on a div element.
I wrote a little something recently about using ARIA attributes as selectors in CSS. For me, one of the advantages is that because ARIA attributes are generally added via JavaScript, the corresponding CSS rules won’t kick in if something goes wrong with the JavaScript:
Generally, ARIA attributes—like
aria-hidden—are added by JavaScript at runtime (rather than being hard-coded in the HTML).
But there’s one instance where I actually put the ARIA attribute directly in the HTML that gets sent from the server: aria-live.
If you’re not familiar with it, aria-live is extremely useful if you’ve got any dynamic updates on your page—via Ajax, for example. Let’s say you’ve got a bit of your site where filtered results will show up. Slap an aria-live attribute on there with a value of “polite”:
<div aria-live="polite">
...dynamic content gets inserted here
</div>
You could instead provide a value of “assertive”, but you almost certainly don’t want to do that—it can be quite rude.
Anyway, on the face it, this looks like exactly the kind of ARIA attribute that should be added with JavaScript. After all, if there’s no JavaScript, there’ll be no dynamic updates.
But I picked up a handy lesson from Ire’s excellent post on using aria-live:
Assistive technology will initially scan the document for instances of the aria-live attribute and keep track of elements that include it. This means that, if we want to notify users of a change within an element, we need to include the attribute in the original markup.
Good to know!
Sara tweeted something recently that resonated with me:
Also, Pro Tip: Using ARIA attributes as CSS hooks ensures your component will only look (and/or function) properly if said attributes are used in the HTML, which, in turn, ensures that they will always be added (otherwise, the component will obv. be broken)
Yes! I didn’t mention it when I wrote about accessible interactions but this is my preferred way of hooking up CSS and JavaScript interactions. Here’s old Codepen where you can see it in action:
[aria-hidden='true'] {
display: none;
}
In order for the functionality to work for everyone—screen reader users or not—I have to make sure that I’m toggling the value of aria-hidden in my JavaScript.
There’s another advantage to this technique. Generally, ARIA attributes—like aria-hidden—are added by JavaScript at runtime (rather than being hard-coded in the HTML). If something goes wrong with the JavaScript, the aria-hidden value isn’t set to “true”, which means that the CSS never kicks in. So the default state is for content to be displayed. There’s no assumption that the JavaScript has to work in order for the CSS to make sense.
It’s almost as though accessibility and progressive enhancement are connected somehow…
Did you know there’s an imagesrcset attribute you can put on link rel="preload" as="image" (along with an imagesizes attribute)?
I didn’t. (Until Amber pointed this out.)
A handy reminder from Léonie (though remember that the best solution is to avoid the problem in the first place—if you avoid using ARIA, do that).
Making the Clearleft podcast is a lot of fun. Making the website for the Clearleft podcast was also fun.
Design wise, it’s a riff on the main Clearleft site in terms of typography and general layout. On the development side, it was an opportunity to try out an exciting tech stack. The workflow goes something like this:
Comparing this to other workflows I’ve used in the past, this is definitely the most productive way of working. Some stats:
I have some files. Some images, three font files, a few pages of HTML, one RSS feed, one style sheet, and one minimal service worker script. I don’t need a web server to do anything more than serve up those files. No need for any dynamic server-side processing.
I guess this is JAMstack. Though, given that the J stands for JavaScript, the A stands for APIs, and I’m not using either, technically it’s Mstack.
Netlify suits my hosting needs nicely. It also provides the added benefit that, should I need to update my CSS, I don’t need to add a query string or anything to the link elements in the HTML that point to the style sheet: Netlify does cache invalidation for you!
The mp3 files of the actual podcast episodes are stored on S3. I link to those mp3 files from enclosure elements in the RSS feed, which is what makes it a podcast. I also point to the mp3 files from audio elements on the individual episode pages—just above the transcript of each episode. Here’s the page for the most recent episode.
I also want people to be able to download the mp3 file directly if they want (or if they want to huffduff an episode). So I provide a link to the mp3 file with a good ol’-fashioned a element with an href attribute.
I throw in one more attribute on that link. The download attribute tells the browser that the URL in the href attribute should be downloaded instead of visited. If you give a value for the download attribute, it will over-ride the file name:
<a href="/files/ugly-file-name.xyz" download="nice-file-name.xyz">download</a>
Or you can use it as a Boolean attribute without any value if you’re happy with the file name:
<a href="/files/nice-file-name.xyz" download>download</a>
There’s one catch though. The download attribute only works for files on the same origin. That’s an issue for me. My site is podcast.clearleft.com but my audio files are hosted on clearleft-audio.s3.amazonaws.com—the download attribute will be ignored and the mp3 files will play in the browser instead of downloading.
Trys pointed me to the solution. It turns out that Netlify can do some server-side processing. It can do redirects.
I added a file called _redirects to the root of my project. It contains one line:
/download/* https://clearleft-audio.s3.amazonaws.com/podcast/:splat 200
That says that any URLs beginning with /download/ should redirect to clearleft-audio.s3.amazonaws.com/podcast/. Everything after the closing slash is captured with that wild card asterisk. That’s then passed along to the redirect URL as :splat. That’s a new one on me. I hadn’t come across that terminology, but as someone who can never remember the syntax of regular expressions, it works for me.
Oh, and the 200at the end is the status code: okay.
Now I can use this /download/ path in my link:
<a href="/download/season01episode06.mp3" download>Download mp3</a>
Because this URL on the same origin, the download attribute works just fine.
A really great one-page guide to HTML from Bruce. I like his performance-focused intro:
If your site is based on good HTML, it will load fast. Browsers incrementally render HTML—that is, they will display a partially downloaded web page to the user while the browser awaits the remaining files from the server.
Modern fashionable development techniques, such as React, require a lot of JavaScript to be sent to the user. When it’s all downloaded, the user’s device must parse and execute the JavaScript before it can even start to construct the page. On a slow network, or on a cheaper, low-powered device, this can result in an excruciatingly slow load and is a heavy drain on the battery.
Smart thinking from Sara to improve usability for keyboard users by using aria-hidden="true" tabindex="-1" to skip duplicate links:
A good rule of thumb for similar cases is that if you have multiple consecutive links to the same page, there is probably a chance to improve keyboard navigation by skipping some of those links to reduce the number of tab stops to one. The less tab stops, the better, as long as it does not worsen or compromise on other aspects of usability.
I’ve cautiously implemented this pattern now over on The Session where snippets of comments had both a title link and a “more” link going to the same destination.