New feature: ARIA element-valued JS properties

[LeaVerou]

Specification

https://w3c.github.io/aria/#ARIAMixin

Description

Currently, there is aria-attribute-reflection but this is about all aria* JS properties.
However, the ones ending in Element or Elements are a distinct feature, since they provide an imperative way to implement patterns that are otherwise impossible, including:

• cross-root ARIA,
• polyfill features like Reference Target
• prototype ARIA aggregation mechanisms without having to pollute the DOM with ids

Whereas properties that simply reflect the value of the corresponding attribute are a relatively minor consistency improvement.

Name/hierarchy ideas:

• Separate aria-element-reflection key
• New aria-attribute-reflection-element, rename aria-attribute-reflection → aria-attribute-reflection-idref, aria-attribute-reflection becomes a group with both

Documentation

See individual BCD keys

api.Element.ariaActiveDescendantElement
api.ElementInternals.ariaActiveDescendantElement
api.Element.ariaControlsElements
api.ElementInternals.ariaControlsElements
api.Element.ariaDescribedByElements
api.ElementInternals.ariaDescribedByElements
api.Element.ariaDetailsElements
api.ElementInternals.ariaDetailsElements
api.Element.ariaErrorMessageElements
api.ElementInternals.ariaErrorMessageElements
api.Element.ariaFlowToElements
api.ElementInternals.ariaFlowToElements
api.Element.ariaLabelledByElements
api.ElementInternals.ariaLabelledByElements

Browser support

I clauded a testcase here and ran it in all three major desktop browsers.

The results were:

• Chrome 135+
• Firefox 136+
• Safari 16.5+

I did not run it in any mobile browsers.

So basically Baseline 2025, which is meaningfully different than aria-attribute-reflection's Widely Available.

[LeaVerou]

@ddbeck ping?

[ddbeck]

Hi @LeaVerou, my apologies but I'm still waiting on a contract to go through to pay for my time on this work. Until then, I'm not processing incoming features into PRs. I probably won't be able to act on this until the start of August at the earliest. As an alternative, you might consider opening a PR yourself and asking for review in the WebDX chat.

FWIW, I think this is probably a good idea, as the original aria-attribute-reflection feature was created without meaningful input from a domain expert (despite attempts to get some), so it doesn't surprise me that it's overly broad.