O'Reilly

CSS attr, content, and L10N

By on  

I have the privilege of working for Mozilla on the Mozilla Developer Network (MDN).  As with any Mozilla-made website, localization is paramount to MDN, so we must be mindful of that when we put text anywhere on the site.  I was recently working on a feature which made use of CSS content:  a visual notice on an element's pseudo-element which are experimental and only available to beta testers.  The obvious problem in doing so is that hardcoding the generated content message in the stylesheet means I can't localize it;  a definite localization taboo.  The solution was simple:  use the attr expression to pull the localization message from an element's custom data- attribute.

The HTML

Start by outputting the localized text to a data- attribute:

<div class="beta-feature" data-message="{{ _('This feature is only seen by beta testers') }}">
	<!-- some content here -->
</div>

With the text available in an attribute, the CSS attr expression and content will be used to display the text in a pseudo-element:

.beta-feature:after {
	content: attr(data-message);

	/* formatting here */
}

The formatting is up to the developer but the main point is that we get to use the attribute value to display the variable text.

This post isn't groundbreaking and it's not meant to be;  I just want to reinforce how awesome and useful CSS content paired with attr can be.  I love that this strategy prevents the need to preprocess CSS files with the localized text, and love that...it's just so easy!

Track.js Error Reporting

Recent Features

  • CSS vs. JS Animation: Which is Faster?

    How is it possible that JavaScript-based animation has secretly always been as fast — or faster — than CSS transitions? And, how is it possible that Adobe and Google consistently release media-rich mobile sites that rival the performance of native apps? This article serves as a point-by-point...

  • CSS Animations Between Media Queries

    CSS animations are right up there with sliced bread. CSS animations are efficient because they can be hardware accelerated, they require no JavaScript overhead, and they are composed of very little CSS code. Quite often we add CSS transforms to elements via CSS during...

Incredible Demos

  • MooTools Gone Wild: Element Flashing

    If you're like me and lay awake in bed at night, you've flipped on the TV and seen the commercials: misguided, attention-starved college girls fueled by alcohol ruining their futures by flashing lame camera-men on Spring Break. Why do they do it? Attention,...

  • Display Images as Grayscale with CSS Filters

    CSS filters aren't yet widely supported but they are indeed impressive and a modern need for web imagery.  CSS filters allow you to modify the display of images in a variety of ways, one of those ways being displaying images as grayscale. Doing so requires the...

Discussion

  1. Hi, that’s really nice feature. It’s interesting for me, is there any other usage, different from the one that you showed. I’m asking because for me it looks like it’s just better to put the text inside the tag instead of adding it to the data-liked attribute.

  2. I`m also curious, how is this preferable to putting it in the div normally? Using css to dictate content seems it violates the separation of concerns that CSS was meant to fix.

  3. Realize that the message goes into a *pseudo-element*, not inside the beta element itself. The goal is for the message to be applicable to *any* element, so the pseudo element just allows me to hang text above the element itself.

  4. Nicely flexible content/attribute set-up. Very handy way to create either a single message, or multiple, element specific messages and have them displayed, or not, per preference.

  5. Another option is to use data-* attribute with a message key. With :lang selector it’s possible to localize string for different languages. Also in this case you have message value inside of a css file that can be cached. Check out there: https://github.com/chemerisuk/formvalidation.js#internationalization

  6. A good use for this is also to make a styled title (tool tip), using the data-title attribute, and content before to style it.

  7. hamburger

    Do the brackets in your message {{ _(‘This feature is only seen by beta testers’) }} have a special meaning? Or is it just your style of messages?

    • It’s django’s template code to localize the message into the user’s requested locale.

  8. This is very useful for designers and frontend devs working on data-driven websites.

    We’re always having to balance how much content to show or hide in a page. So far the best compromise is to show the essential information, then allow users to “expand” the object to view more details.

    Most of us store that extra information in divs or spans or title attributes, which always seemed like a hack-y way to me. I always felt like the extra information should be a property of the element, and not an extra span or div nested and initially hidden inside the element.

    I’m glad we can now harness the power of data-attributes with CSS!

Wrap your code in <pre class="{language}"></pre> tags, link to a GitHub gist, JSFiddle fiddle, or CodePen pen to embed!

Recently on David Walsh Blog

  • Loading Static Templates for Intern Testing

    I use Intern by SitePen for all of my JavaScript functional testing.  Intern has loads of features other functional test frameworks don't and it's completely Promise-based -- something I got very used to when I used the Dojo Toolkit every day. Async test creation can...

  • Convert Video to mp3

    Let's all be honest for a moment:  we've all ... not paid for ... music.  Whether it was via a file sharing app like Kazaa or Napster, or it was downloading and seeding on bittorrent, or maybe even downloading a music video and ripping its audio,...

  • Sort git Branches by Date

    I'll be first person to admit I don't do as much git repository maintenance as I should.  I rarely delete branches which have been merged, so a git branch execution shows me a mile-long list of branches that likely aren't relevant.  The best way to find branches I've recently...

  • Best Tools and Resources for Web Professionals in 2015

    Looking for the right resources to help you satisfy the needs of your clients? On the lookout for the best tools to help you increase your revenue? Searching for the right software to help you improve your business? Well, then you’ve come to the right place....

  • JavaScript Polling

    Polling with JavaScript is one of those ugly but important functions within advanced front-end user experience and testing practices.  Sometimes there isn't the event you can hook into to signify that a given task is complete, so you need to get your hands dirty and simply poll for...