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Bug 1962340 - Use a resize event instead of a timeout to tell renderi… - #416

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@hiikezoe

@hiikezoe hiikezoe commented Oct 26, 2026 •

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…ng updates apart in new-scroll-event-dispatched-at-next-updating-rendering-time.html. r?#layout-reviewers

Timer callbacks are queued on the timer task source and rendering updates on the rendering task source, and the event loop picks among task queues in an implementation-defined manner, so a timeout set in a requestAnimationFrame callback may run after the next rendering update. The resize event fired by the next rendering update's resize steps, right before its scroll steps, marks the start of that update instead.

https://html.spec.whatwg.org/#event-loop-processing-model


Lando: link
Bugzilla: bug 1962340

⚠️ This pull request has 5 warnings.
🚫 This pull request has 1 blocker.

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github-actions Bot changed the base branch from main to autoland October 26, 2026 22:42
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Warning

The target branch has been automatically set to autoland.

Please Edit this PR if this wasn't your intention.

@hiikezoe

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CC @emilio , @mustaqahmed

@hiikezoe

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Note that I ran the modified test on Chrome (on Linux) and Safari, the test passed on 20/20, 20/20 respectively so I would say it's stable.

@mustaqahmed mustaqahmed left a comment

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The change LGTM. I am asking for a comment update, and optionally a resize0 logging too.

…ng updates apart in new-scroll-event-dispatched-at-next-updating-rendering-time.html. r?#layout-reviewers

Timer callbacks are queued on the timer task source and rendering updates on the
rendering task source, and the event loop picks among task queues in an
implementation-defined manner, so a timeout set in a requestAnimationFrame
callback may run after the next rendering update. The resize event fired by the
next rendering update's resize steps, right before its scroll steps, marks the
start of that update instead.

https://html.spec.whatwg.org/#event-loop-processing-model
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No new issues detected. This pull request is 🆗

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No new issues detected. This pull request is 🆗

@lando-worker

lando-worker Bot commented Oct 29, 2026

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Pull request closed by commit b0161d1

lando-worker Bot pushed a commit that referenced this pull request Oct 29, 2026
…… r=mustaqahmed,emilio

…ng updates apart in new-scroll-event-dispatched-at-next-updating-rendering-time.html. r?#layout-reviewers

Timer callbacks are queued on the timer task source and rendering updates on the rendering task source, and the event loop picks among task queues in an implementation-defined manner, so a timeout set in a requestAnimationFrame callback may run after the next rendering update. The resize event fired by the next rendering update's resize steps, right before its scroll steps, marks the start of that update instead.

https://html.spec.whatwg.org/#event-loop-processing-model

Pull request: #416
@lando-worker lando-worker Bot closed this Oct 29, 2026
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3 participants