[meta] MutationObserver improvements tracking issue

[LeaVerou]

I recently did some research on what open MutationObserver proposals there are and their status, and figured it may help others too, so I’m opening this to track them.

Perhaps someone with permissions could add them as child issues or assign them a label (happy to do it myself if someone wants to give me deh powah).

If I missed any feel free to edit this and add them, or comment and I'll edit it myself.

Specific proposals (older to newer):

• Disconnect single target instead of all #126 (MutationObserver.prototype.unobserve())
• Consider adding localNameFilter to MutationObserver #398
• Make it possible to observe connected-ness of a node #533
• Proposal: add childFilter option to MutationObserverInit #905
• childList records across multiple MutationObservers are observed in fundamentally incorrect order #1111
• mutationObserver.disconnect({ flush: true }) #1283
• MutationObserver flag to observe mutations in (open) shadow trees to facilitate polyfills of HTML syntax #1287
• Allow MutationObserver to observe (certain) element property changes #1340
• Allow MutationObserver to observe across <slot>s #1415

Unclear:

• MutationOvserver and DOMNodeInsertedIntoDocument #1227

Closed but not implemented

• MutationObserver with querySelector for elements #77 — too slow
• MutationObserver attribute filter ignores attributes with a namespace #1364 — doesn't follow the new feature template
• MutationObserver callbacks happen in unexpected order. #1105 — not actionable

(I gave up on collecting these early)

[annevk]

@LeaVerou thanks for doing this work! I've given you write access to whatwg/dom (so you can create labels here) and triage access to most other specifications. I'd suggest topic: mutation observers as label.

[LeaVerou]

@LeaVerou thanks for doing this work! I've given you write access to whatwg/dom (so you can create labels here) and triage access to most other specifications. I'd suggest topic: mutation observers as label.

Thanks! Done on the issues mentioned here. I may look through closed issues at some point and add the label to that too, but no promises.
Do you want me to also add as sub-issues or do you generally not use that?

[annevk]

It's fairly new so we haven't really experimented with it. Go ahead if you think it helps! And no need to triage closed issues I think.

[smaug----]

Agenda+ to figure out what we should do here.

[cwilso]

discussed.