Consider use of innerHTML in ariaHerald

[mbarlow12]

From phetsims/gravity-force-lab#131.

We're currently setting the textContent of the aria-live elements which strips HTML Entities (e.g. ×) instead of rendering them.

It may be more pertinent to simply spell out such cases, but we could also consider adding a flag to the config object that indicates the inclusion of HTML in the alert.

[jessegreenberg]

I think this is a good idea, could we handle this like we handle setting inner content for accessible content in the PDOM? What if ariaHerald.updateLiveElement were changed to use AccessibilityUtil.setTextContent?

[jessegreenberg]

I committed this and it seems OK with NVDA. @mbarlow12 can you please review and test if this fixes things in VO?

[mbarlow12]

Thanks @jessegreenberg. My only hesitation would be whether we want to fully support all HTML features in our alerts. The most significant use case I can think of would be for MathML, which may be a valid consideration as we move onto a11y tooling in more math-heavy sims.

Can you think of a situation where it would be useful to include generic HTML in an aria-live element?

[mbarlow12]

Results are mixed. The entity is now correctly rendered, but VO appears to contextually read "multiplication" or "times" depending on some unknown parameters. aria-live elements are read as "multiplication" while PDOM list items appear as "times". Very odd.

[jessegreenberg]

OK understood, thanks for testing. In that case we may have to go back to passing in "times" as a full string. We do not have control over how VO interprets the context unfortunately.

[mbarlow12]

@jessegreenberg I'll do a little testing/digging this week to see if there might be a way for us to tweak what VO reads.

[jessegreenberg]

Closing this issue for now, we will work on this naturally when we require more complicated entities in alerts.