Paul Irish

I make the www fun.

Accessibility and Developers

Jacob Thornton has an inspiring slide deck on accessibility that brings to fore some of the concerns that web developers have with implementing features around accessibility.

For a very long time, developers have been told about making websites ‘accessible’. Like it is a faucet that should be turned on or off. Till Victor Tsaran’s demonstration of using a screenreader (which was in 2007 - a very long time since accessibility evangelism began) - very few web developers had any idea of the real immediate impact of implementing accessibility features.

During a Nicholas Zakas & Victor Tsaran talk years ago I finally grokked the easiest rule for a first step towards accessibility. For such a long time, we conflated functionality while JavaScript-disabled with “being accessible”. It took me years to learn that making it keyboard-navigable was the top priority.

Just as a datapoint, The WebAIM survey results (published yesterday) reveal 98.6% of screenreader users have javascript enabled.

What we need

People like Jason Kiss and Steve Faulkner who detail the behavior and support in browsers and screenreaders are providing the developer community with invaluable knowledge, stuff that is far more worthwhile than publishing a yet another list of you-should-do-these-things. (See also my resources list in the semantics post).

Most developers have no idea what effect adding ARIA markup to our documents has on people using screenreaders. We need that. Actual before-and-after video stuff makes this topic real. See zomigi’s recent post: videos of screenreaders using ARIA, for great examples.

Most developers have no idea how to implement ARIA. The W3C Primer that looks like a spec is not at all appropriate for a web developer audience.

Just like it’s valuable to witness an a11y usability session where you see how disabled people use your site, I think it’d be useful for the accessibility community to see how developers build, because thus far there has been a disconnect in communicating effectively. I don’t think we need more on the ground evangelism yet. There is a dearth in online resources at the moment, developers need to know these practical ways of using and having users benefit from accessibility techniques:

  • Which features should I use and which should I avoid (which features are actively harmful because of shoddy screen reader/other a11y tech support?)
  • What are the top priorities for developers to implement?
  • Videos of screenreaders in use (Thanks Zoe!)
  • What one thing can I do as a web developer to my sites and apps that dramatically improves the UX for disabled users
  • How do some of these features work? What are they for? A demonstration of how each feature makes an impact or gets used by a user would be most helpful (e.g. how do focus rings work?).

Screenreaders & browsers

Also, I’m not quite sure how everyone else feels, but from here it feels like yelling at a fucking brick wall with JAWS and Window Eyes. We just kinda hope and pray their support for things improve. As a pragmatic approach, I tell developers that if it works in NVDA, good enough. We have a mess of browsers we need to support already, dealing with ATs that lag years behind is not at all feasible.

A lot of developers do not understand that accessibility first comes from implementing the platform accessibility API by browsers such that screen readers can take advantage of the rendering. Most operating systems expose an API that allows browsers to map what is rendered on the screen to one of the interfaces that the operating system’s accessibility API exposes.

A series of stairs and a ramps interleaving between them

Unfortunately, there has been no specification, so each browser has been left to do whatever it wants in terms of defining the relationship between a HTML element and the accessibility interface. Hopefully this will change with the HTML to Platform Accessibility API implementation guide and ensure each browser exposes each element consistently to the Platform Accessibility API.

Which shores up a greater concern: Better accessibility starts with the browser (and the platform). Browsers should be able to handle content loaded dynamically rather than expecting developers to do it for them. If content on a page that is displayed is altered, it needs to be noted to the accessibility api transparently instead of having developers bolt on extra markup to do so.

Accessibility should not be opt-in but opt-out.

This post is a elongated version of the comment I left on Karl Grove’s Barriers to improving the accessibility game plan. It was probably the best post on a11y I’ve ever read. I really liked his approach in evolving the a11y strategy and left my thoughts.

Thanks to Divya Manian for her thoughts and words on this post. Thanks to Jason Kiss for reviewing drafts.

June 1: Added link to freshly published WebAIM survey results 2012. I encourage you to read the whole thing, as it’s a fascinating view into an audience we have challenges understanding.

2013.06.06: This has been translated into Czech: [Dostupnost a Vývojáři](

Talk: Tooling & the Webapp Development Stack

One of the things I recognize at Google is how productive developers surround themselves with powerful tools for iterative development and debugging. For us front-end developers, the ecosystem of tools has exploded in the past two years, as we have a lot more software and libraries beyond Firebug and jQuery to help us build webapps. In the talk below I walk through the current ecosystem of tools and how they can make your development experience a more enjoyable one.

My slides:

Because there are so many tools around, I wanted to break them down somehow. I think contextualizing the tools as to what phase of development that assist with works well:

(You could think of the Y-axis here as the amount of code in a project..)

Looking at our tools this way we end up with:

  • Boilerplate
    • You likely start a project with more than a single blank text file.
  • Authoring Abstractions
    • CSS preprocessors, Languages that transpile to JS, Templating
  • Frameworks and Application Stack
    • Clientside MVC, UI Components, Widgets
  • Iteration Workflow
    • Browser Devtools, Browser/Unit/Integration Testing
  • Performance Tuning
    • Profiling, Memory mgmt, browser instrumentation
  • Build & Optimization
    • Minifiers, Concat, Image compression…
  • Deploy
    • Continuous Integration, Continuous deployment

I’ve been thinking a lot about workflow and integrating these tools together. Screencasts like Andrey Tarantsov’s Sublime Text Workflow really excite me and I’m eager to see more people exploring a robust development setup.

2012.05.16: Mr Jon Kemp wrote up an outline of my talk with all the links, for easy clickability:

Vendor Prefixes Are Not Developer-friendly


The premise of prefixes makes unrealistic demands on how developers maintain sites

There’s a lot of conversation about making prefixes work (by changing policy), but I believe they already are at odds with the developer workflow. In this proposal I hope to show that:

  1. prefixes are not developer-friendly
  2. recent features would have been in a much better state without prefixes
  3. implementor maneuverability is not hampered without prefixes

The developer experience

If I’m using a feature that’s prefixed, I have a choice of using a tool to help me manage outputting the various prefixes I need or I’ll do it myself.  Based on my informal poll last week it looks like 40% of developers are not using tools. Without tool usage, authors are not including -ms-, -o- or the unprefixed variants. Page 4 of Mozilla’s prefix report verifies this; developers don’t write necessary prefixed properties about half the time (e.g. -o-transform) and in fact, they already write out the unprefixed variant well before the spec goes to CR (and do this well before adding in -ms- or -o- compatibility).

Data summarizing prefixes’ failure with developers [Mozilla’s prefix report, page 4]

This matches my experience as well. I don’t want to return to this code to maintain it, so I’m going to add the unprefixed version. There is less of a cost to me leaving the unprefixed version and assuming I won’t need to change it vs. returning to my CSS of shipped-to-production work to add unprefixed variants each time a feature hits CR.

Any successful evangelization plan for prefixes relies on tools, but all tools prioritize the unprefixed state. prefix-free, compass, and css3 please (I’m a tool vendor, too) all heavily suggest starting with the unprefixed state. So any successful evangelization push will just result in the unprefixed version being 100% deployed from the get-go, which ties implementors hands anyway and defeats the purpose of the prefix. I don’t have data to show that developers are not returning to their deployed, production code to update prefixes, but anecdotal evidence suggest so. Opera’s Web Opener team, for example, reports a <10% success rate when directly contacting sites to request updates to their prefixes.

PPK wrote “If standards make web developers’ lives much harder, web developers ignore standards. This was true back in 1998, it’s still true today.” Without prefixes, implementors have an opportunity to empower developers to do the right thing while still allowing room for innovation.

Existing W3C prefix policy provides false expectations

PPK covered this ground well last week, but in short the policy of binding prefix-drop to CR has failed plenty. Developers have no expectation of when this will happen, nor should they. Mozilla’s roc has confirmed developers are using prefixes and they won’t stop regardless of their supposed “experimental” status.

Let’s imagine there were no prefixes

So without prefixes, vendors hands would be tied and the first implementation to ship would be the one to stick, right? Nah. I think we can walk through a few examples from recent history too see what it would have been like if there had been no vendor prefixes in play.

transitions, transforms, animations

While plenty of implementation bugs were fixed, the developer would never have updated their syntax and would have complete browser support.


No problems. No changes.


Gradients has been the most tumultuous css spec, but if they had been implemented without prefixes, the feature would be in a better situation today.

Browsers discard properties and values they don’t parse successfully, so developers would have just included a cascade of the iterations of the spec. This would have successfully targeted all shipped versions of gradients:

.blacktowhite {
  background-image: gradient(linear, left top, left bottom, from(black), to(white)); /* initial webkit proposal */
  background-image: linear-gradient(top, black, white); /* mozilla proposal */
  background-image: linear-gradient(to bottom, black, white); /* likely the CR */


Mozilla started Flexbox v1, WebKit followed with a slightly stronger implementation. Both Alex Russell (post) and I (article) recommended boilerplate code that assumed no change for unprefixed state and blocked out IE10’s upcoming implementation.  

Flexbox v2 debuted and has an implementation in Chrome. Syntax is already different enough that the fallback story is happy. Without prefixing, the resulting browser support of shipped author code would be better. Again, I see no drawbacks in this example had these properties not been prefixed.


Soon after this feature debuted, shims were written to manage all prefixed implementations including the unprefixed state.  (Sorry). Combined with quick adoption, browser  have as much ability to change the feature as they would if it were unprefixed to start (that is, not much ability).

Risks and Resolutions

In CSS, new breaking changes have to introduce syntax changes that would break previous parsing attempts, as seen in the gradients example. However, if the semantics of a feature changed without syntax changes, we’d have a situation where developers are forced to detect each behavior and write compatibility code.

border-image introduced a similar situation recently: WebKit changed its semantics and required a `fill` keyword to match previous behavior. Sounds like trouble, but this change happened when the unprefixed variant was exposed, matching implementor best practices of changing a feature. The result: Greg Rewis of Adobe blogging that Chrome broke his site. This is truly how it is supposed to work, but still expectations are broken. Developers have plenty of motivation to leave in the unprefixed state at the beginning, but this means that any change will always break them. With prefixes or without prefixes, we would have gotten the same resolution here.

In JavaScript/DOM we have a more secure safety net, as behavior can be detected. Take for example querySelectorAll(); it was shipped without prefix and while implementation differences exist, JavaScript libraries detect and route around them. Of course, semantics can change and the prefix → unprefix move provides an opportunity, but in my experience it’s more common to see these changes happen early on (like blob.slice()’s change).

Without prefixes there will be no mechanism to notify developers “beware, thar be dragons!”. Prefixes don’t do this now, as their removal isn’t prioritized so developers accept them as a fact of life rather than an indication of instability.  The solution: getting accurate metrics of feature usage and adoption can inform implementors of if it’s too late to change a feature or still early enough to modify.  

Yes, but…

As vendor prefixing is a well-worn debate, allows me to deflect common challenges to this proposal to:

  1. Vendor Prefixes Are Hurting the Web by Henri Sivonen (see “Pre-Emptive Rebuttal to the Most Common Counter-Arguments” and on)
  2. Alternatives To Supporting -webkit Prefixes In Other Engines by Robert O’Callahan
  3. CSS vendor prefixes considered harmful by PPK (from 2010)

Logical Actions

  1. The community to evangelize use of tools like Compass that protect authors from bad authoring practices and so folks who publish tutorials don’t solely define their -webkit- styles.
  2. Browsers to track feature adoption to inform better decision-making around changes. (Answering the question: Are we stuck?)
    • This data should be public and update regularly.
    • Should be based on pageviews, to accurately weigh when a implements something
  3. Other browsers to implement a defined set of -webkit- prefixes on their mobile browsers. I don’t see a way around this nor do I think it’s bad.
  4. Drop the notion that evangelism gets us out of this mess. I’ve been doing this evangelism myself for the past 3 years, but I’m also a realist. This situation needs new policy and (clearly) needs speed out of the CSS WG.
  5. Browsers to clarify a feature detection strategy that it supports. For example, developers have no reliable way of detecting Chrome’s 3D transforms support [1, 2] or discounting Chrome’s -webkit-hyphens false positive[3]. All proposals for handling experimental properties need accurate feature detection techniques to be effective.

In summary, the ideal developer experience is 1) using tools to manage prefixes and 2) always using the unprefixed state to reduce maintenance cost. These two facts eviscerate the benefits that prefixes were introduced for, leaving only the drawbacks.