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I have a blog over on Blogger at http://blog.adrianroselli.com/. I post regularly about trends and news in web development, usability, accessibility, social media, best practices, and anything else falls into the very broad category of "web related." Below is just the latest post from my blog, with links to more entries on the side. You can save yourself some hassle and just subscribe to the RSS feed and let it come to you.

Don't Use Tabindex Greater than 0

Animated GIF showing the tab order on a page using the default Re-CAPTCHA, which sets a tabindex, forcing a keyboard user through six tab-stops to get to the Skip to content link.

Tabindex had the potential to be a useful attribute. A developer could set the order in which focus is moved on a page as a user tabs through the form (or links, or content). It became a stop-gap for forms and pages that relied too heavily on absolute positioning and didn't flow naturally. The problem is that it is often set by developers who don't have any idea of what the user expects.

This mis-use has effectively guaranteed that using tabindex values greater than zero is a bad idea. If, as a developer, you have to use tabindex on a form, then the page itself probably isn't laid out well and will only confuse keyboard users and, more importantly, users of assistive technology.

Browsers take any element with a positive tabindex value and promote it to the front of the pack for tabbing through the page. Only after a browser gets through all elements with a tabindex does it then fall back to source order. It doesn't matter if your tabindex is one million, it will still trump everything on the page that doesn't have a tabindex.

This is such a well-known issue that the W3C HTML Working Group is working on new language to deprecate values greater than zero. There is even a bug filed against the HTML specification to that effect.

For more detail I encourage you to read Léonie Watson's piece, Using the tabindex attribute.

Tabindex Best Practices

Here are some tips to use tabindex properly.

tabindex="-1"

Setting tabindex="-1" allows you to set an element's focus with script, but does not put it in the tab order of the page. This is handy when you need to move focus to something you have updated via script or outside of user action.

tabindex="0"

Setting tabindex="0" will take an element and make it focusable. It doesn't set the element's position in the tab order, it just allows a user to focus the element in the order determined by its location with the DOM.

tabindex="1" (or any value > 0)

Do not set a tabindex="1" or any value greater than zero (or any positive value).

The Example

The example in the animated GIF above is unfortunate in that the site developers themselves don't set a tabindex (I found this at User Experience Impossible: The Line Between Accessibility and Usability on the GSA's DigitalGov site). Instead, for reasons I cannot explain, they use a CAPTCHA on the comment form. The implementation they chose, however, inserts its own tabindex values.

This means that as the user starts tabbing through the page, he or she is first sent to the text entry field on the CAPTCHA in the comments section.

Even as a sighted mouse-user, I was confused how I got there as I tabbed into the page. It takes five more tabs to get to the link that allows the user to skip to the content (which appears first on the page).

This also creates a problem for a user who is filling out the comment form, as tabbing from the Name and then Email fields puts the user on the privacy link for the CAPTCHA, but not into the field where he or she can type the text to submit the form. Some users may never know there is a CAPTCHA there depending on how they got to the comment form.

Paul J. Adam shows the offending code in a tweet, which I will steal and display here since I'm too lazy to screen-capture it:

I don't want to beat up the DigitalGove folks, but this is a great example of how a perfectly functional page (regardless of how I feel about the hover versus focus styles) can be ruined by not testing it after adding third-party widgets.

Bonus: Don't Use CAPTCHA

There's a lot written about this. I'll just link to this from the W3C: Inaccessibility of CAPTCHA

Update: November 19, 2014 at 1:25pm

I still haven't heard back from the folks at DigitalGov on Twitter, but Jonathan Rubin from the GSA responded (though he did ping an account that hasn't tweeted in a month), I just haven't heard any more from him. I've also left a comment (pending moderation) on the site itself.

I discovered while trying to leave a comment that the ReCAPTCHA is served via HTTP while the page is served via HTTPS. One of my browsers (IE) blocks it by default because it's an insecure element on a secure page. That means I won't experience the tabbing problem, but it also means that I cannot leave a comment as the form silently breaks without the ReCAPTCHA. I've left a comment for that as well (but I didn't see a preview and I got no error messages, so, yeah).

Here's the rub — I don't want people beating up the DigitalGov team. That these folks have put forth such a good effort but fallen down on one issue is not uncommon. We all do that. I do it (last week Karl Groves discovered a CAPTCHA on this blog that I never saw). That I found it on a post about accessibility is unfortunate, but it also means the DigitalGov team needs to be more responsive when provided with clear technical solutions and learn to test after each feature addition. Like all the rest of us who work in or near accessibility.

Update: November 19, 2014 at 6:25pm

The comments I posted on the DigitalGov page are still in moderation queue, even though comments posted well after mine have been approved. You can see them still in moderation in the screen capture.

Given my suspicion that they won't be posted (since I've heard nothing back from the initial conversation with the Twitter account), I'll post the comments here. The first was a reply to a site admin following up on a comment from another user noting that the keyboard navigation of the page is broken. My second comment is a follow-up.

Screen shot of comments.
The content of my comments is in the page content.

The First Comment

November 19, 2014 at 12:44 PM

The ReCAPTCHA on this page uses a tabindex value. Since browsers honor tabindex values before falling to source order in the DOM, the very first (through fifth) tab stop on the page is the CAPTCHA. It takes six presses of the tab key to get to the “Skip Navigation” link. That’s the issue I suspect TRUEAXGUY is referencing.

I’ve mentioned this issue to DigitalGov on Twitter (https://twitter.com/ aardrian/status/ 534751243491901440), heard from Jonathan Rubin of the GSA on Twitter (https://twitter.com/ jonathan_rubin/status/ 534788879518539776), and used it as motivation on writing a post about tabindex best practices for accessibility: http://blog.adrianroselli.com/2014/11/dont-use-tabindex-greater-than-0.html

As I’ve said before, I am happy to help, but the easiest fix is to remove ReCAPTCHA or, failing that, go to line 449 of this page (I don’t know where you call it in your pre-rendered code) and remove this: tabindex: 4 (making sure to also remove the comma from the line before it so the JavaScript doesn’t break).

The Second Comment

November 19, 2014 at 1:24 PM

Also, the ReCAPTCHA is blocked by one of my browsers because it’s served as HTTP instead of HTTPS, while the page itself is served as HTTP. This means some users may never even be able to comment (no error messages are displayed on submission, it just silently fails).

Since you have moderation enabled, and since CAPTCHA is already a proven accessibility barrier, and since it’s messing with keyboard navigation, I strongly suggest you remove ReCAPTCHA altogether.

November-18-2014
See it on the blog with any comments.