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