Intent to Deprecate and Remove: setting Event.cancelBubble to false

[Peiyong]

Primary eng emails

l...@chromium.org

Summary

Make Event.cancelBubble=false a no-op.

Motivation

According to https://github.com/whatwg/dom/issues/211, setting cancelBubble to true is considered as an alias to stopPropagation(), and https://dom.spec.whatwg.org/#dom-event-cancelbubble indicates setting cancelBubble to false should do nothing.

Compatibility And Interoperability Risk

No. UseCounter is indicating very low usage.

Firefox[0] and Safari[1] have already changed the behavior to meet the spec, bug was filed on Edge's side[2].

[0] https://bugzilla.mozilla.org/show_bug.cgi?id=1324380

[1] https://bugs.webkit.org/show_bug.cgi?id=166018

[2] https://developer.microsoft.com/en-us/microsoft-edge/platform/issues/10266390/

Alternative implementation suggestion for web developers

None.

Usage information from UseCounter

https://www.chromestatus.com/metrics/feature/timeline/popularity/1348 indicates it's rare that cancelBubble actually changes which callbacks are invoked.

https://www.chromestatus.com/metrics/feature/timeline/popularity/1349 indicates it's likely common to change cancelBubble from false to true.

https://www.chromestatus.com/metrics/feature/timeline/popularity/1350 indicates it's super rare to change cancelBubble to false.

So, it's safe to make Event.cancelBubble=true an alias to stopPropagation() and Event.cancelBubble=false a no-op.

OWP launch tracking bug

https://bugs.chromium.org/p/chromium/issues/detail?id=675549

Entry on the feature dashboard

We don't have an entry on the feature dashboard.

Requesting approval to remove too?

Yes.

[Philip Jägenstedt]

It's very encouraging to see this has already changed in Gecko and WebKit, minor changes like this often have a tendency to drag on for years. LGTM1, but please do add a chromestatus.com entry for this change.

[Rick Byers]

LGTM2

[Rick Byers]

I should say that I think the only real question here is whether we should have a deprecation message for a milestone or not.

I checked the internal UseCounter data.  It's also essentially zero (0.00002% - just enough non-zero to prove the counter is working at all).  Given other browsers have long behaved this way and the unlikelyhood of anyone actually depending on the semantics, I'm fine with skipping the deprecation period.  Though it certainly wouldn't hurt if anyone feels differently.

[Chris Harrelson]

LGTM3

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