Custom elements at TPAC: IDREF attribute APIs; etc.

[Dominic Cooney]

I have been setting up agenda items for custom elements at TPAC.

Last week we talked about a "parser has set all attributes" and "end tag parsed" callbacks with some analogies to built-in INPUT avoiding creating its shadow DOM until it knows its type and SCRIPT doing processing when it has its content.

Could you share some Polymer use cases for these callbacks?

I investigated the "element reference sharing" idea in this doc. It appears that LABEL "for" in Blink is just implemented as ~getElementById. The IDs are cached in Blink, but that's just consulted on demand when LABEL wants to know what it is for; Polymer could do the same. There's no callback when the referenced element changes or disappears. It appears aria-describedby is the same.

On the other hand there's the mess of form association which is very active. It's a hodgepodge so I'm not sure it's great to draw standardization lessons from.

Is there a use case or some evidence of undue inefficiency/hardship I could draw from to advocate for this?

Thanks!

Dominic