Add onfocusin and onfocusout to event handler content attributes

[josepharhar]

MDN URL

https://developer.mozilla.org/en-US/docs/Web/HTML/Global_attributes

What specific section or headline is this issue about?

"The event handler attributes:"

What information was incorrect, unhelpful, or incomplete?

This list does not include "onfocusin" and "onfocusout"

What did you expect to see?

"onfocusin" and "onfocusout" to be in the list like "onfocus" is

Do you have any supporting links, references, or citations?

I am adding these event handler content attributes to the spec here: whatwg/html#10235

Do you have anything more you want to share?

I'm not sure if there's anywhere else on MDN that these event handler content attributes should be enumerated, but when I searched for "onfocus" this was the only page I found.

[hamishwillee]

Looking at Chrome (at least) the events exist (focusout, focusin), but the associated onXxx() handlers do not - which makes sense, because that is what you're adding in whatwg/html#10235.

MDN does not document "stuff" until there is at least one browser implementation, so this needs to be on hold for a bit.

When this is implemented, yes then https://developer.mozilla.org/en-US/docs/Web/HTML/Global_attributes would need to be updated. The two events would also need to be updated in their syntax boxes to add the onXzzz() handler. You can see what this would look like by comparing with the focus event syntax section