- From: Joseph Scheuhammer <clown@alum.mit.edu>
- Date: Mon, 21 Apr 2014 10:58:37 -0400
- To: public-pfwg@w3.org
Bryan wrote: > Hi Birkir, you can control the association by not setting > aria-describedby until the error is made visible, then when focus is > set to the field after this, it will be announced. > What Bryan said. Furthermore, aria-describedby is intended to provide a good description of the associated form field. Setting that description permanently to "invalid field" is not a good description. In fact, it's a false description when the field is valid. That's an author error. It's analogous to setting aria-invalid="true" on the field and never changing it, regardless of the contents of the field. (Aside: authors should be using aria-invalid as well in the scenario described). Steve wrote: > yes, refer to section 5.6.1.3. Text Alternative Computation of the > ARIA implementation guide: > http://www.w3.org/WAI/PF/aria-implementation/#mapping_additional_nd > > > Skip hidden elements unless the author specifies to use them via > an |aria-labelledby| or |aria-describedby| being used in the > current computation. By default, users of assistive technologies > won't receive the hidden information, but an author will be able > to explicitly override that and include the hidden text > alternative as part of the label string sent to the accessibility API. > A use case is where aria-describedby references a tooltip. The visibility of the tooltip varies over time -- it pops up and vanishes depending on what the user does. Nonetheless, the tooltip text remains the same, and is available to the user/AT via the accessibility API. In general, the visibility of a description is orthogonal to that description's text. Aside: Recently, FireFox added support for a "description-changed" event when description text changes [1]. That event is part of the accessibility API (e.g, IA2, ATK). Going forward, these events are useful in situations where a description changes, including those that depend on the validity of a form field, and the description is referenced using aria-describedby. Hope that helps. [1] https://bugzilla.mozilla.org/show_bug.cgi?id=991969 -- ;;;;joseph. 'A: After all, it isn't rocket science.' 'K: Right. It's merely computer science.' - J. D. Klaun -
Received on Monday, 21 April 2014 14:59:04 UTC