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Discussion on: A Concurrent Mode-Safe Version of useRef

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reaysawa profile image
João Paulo •

Thanks for sharing!

I'm curious about this line

Promise.resolve().then(()=> raw.isRendering = false)

What guarantees do we have that the promise will only resolve in the commit phase of React?

As far as I'm aware, only useLayoutEffect is guaranteed to be ran once in the commit phase. See this video: youtube.com/watch?v=V1Ly-8Z1wQA at 16:05.

If that's correct, then we could change it to something like:

  raw.isRendering = true;
  raw.currentValue = raw.comittedValue;
  useLayoutEffect(() => {
    raw.isRendering = false;
    raw.comittedValue = raw.currentValue;
  });
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And I think that would work together better with React's guarantees. What do you think?

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eddiecooro profile image
Eddie •

Agree 👍
Also, if we assume this, what happens to time slicing?

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sarimarton profile image
Marton Sari •

This doesn't work guys. Have you tested it?