api.FontFaceSet - Safari doesn't support loading events

[adixon-adobe]

What type of issue is this?

Incorrect support data (example: BrowserX says "86" but support was added in "40")

What information was incorrect, unhelpful, or incomplete?

I recently ran into an issue with the loading, loadingdone and loadingerror events on Safari, where they don't actually trigger when adding the events from the document.fonts API. I confirmed that there's a Safari issue tracking this at https://bugs.webkit.org/show_bug.cgi?id=304091

The MDN docs for this at https://developer.mozilla.org/en-US/docs/Web/API/FontFaceSet indicate that these should be working in Safari.

What browsers does this problem apply to, if applicable?

Safari

What did you expect to see?

I expected to see these events listed as not supported in Safari in the MDN docs.

Did you test this? If so, how?

I ran into this in my application while trying to work around a bug related to font loading, and was surprised when I found these events didn't work in Safari.

Can you link to any release notes, bugs, pull requests, or MDN pages related to this?

Safari bug: https://bugs.webkit.org/show_bug.cgi?id=304091

Do you have anything more you want to share?

No response

MDN URL

No response

MDN metadata

No response

[caugner]

Based on the bug and the reverted WebKit change, it is plausible that the onloading* event handlers are supported, but the events never fire.

So we should handle this similar to MIDIAccess.statechange_event in Firefox and PermissionStatus.change_event in Safari, i.e. marking the events as partial with a corresponding note following prior art.