[Bug 27294] DOM needs a way to get element's computed ARIA role and computed label string

https://www.w3.org/Bugs/Public/show_bug.cgi?id=27294

--- Comment #16 from Dominic Mazzoni <dmazzoni@google.com> ---
The main use-case I have in mind is feature/capability detection. As new ARIA
roles are added, and more generally as the ARIA spec improves, web authors need
a way to determine whether a particular user agent supports those features, and
provide a polyfill if not.

In the case of ARIA roles, a computedRole() interface would allow a web app to
determine whether a particular role is recognized, and if not provide an
appropriate substitute. While there's existing support for listing multiple
roles, the interaction between ARIA roles in the DOM hierarchy is pretty
important and web authors might want more control over them.

As for computedLabel(), one of the possible future enhancements proposed for
ARIA is the ability to specify elements that don't have an id, for ARIA
attributes that currently require an IDREF. For example, instead of
aria-labelledby="foo", two proposed ideas would allow you to use a
querySelector string in place of the IDREF, or to use JavaScript to associate a
specific DOM element with another element's ariaLabelledBy reflected attribute.

If either of these ideas makes it into the ARIA standard, authors might be wary
of taking advantage of them when they're not supported in all browsers. Having
computedLabel() provides a convenient alternative: use it to test for the
presence of the new feature, and provide a polyfill if not.

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Received on Thursday, 18 December 2014 17:33:08 UTC