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alexreardon avatar alexreardon commented on June 24, 2024 1

Here is the full text of the set state optimization [as at 13th April]:

If the new value you provide is identical to the current state, as determined by an Object.is comparison, React will skip re-rendering the component and its children. This is an optimization. Although in some cases React may still need to call your component before skipping the children, it shouldn’t affect your code.

useState docs

I think that wording the caveat that the re-render optimization is skipped "in some cases" implies that the de-optimization should only occur in outlier circumstances (eg nested set states in an effect), and not for standard happy path cases.

I think that skipping the re-render optimization for a happy path case is a bug.

I appreciate that component renders should be pure, and so an additional re-render should not cause any functional problems. However, I still think that this current behaviour is incorrect.

The current behaviour hurt me when I was trying to write a test to assert that a component should not render after a particular event, but a render did occur. It would be fair to ask: "Why assert render behaviour in a test?". I think it is fair to assert re-rendering behaviour given that re-rendering can be expensive with react

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Andarist avatar Andarist commented on June 24, 2024

Might be a duplicate of #18098

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vkurchatkin avatar vkurchatkin commented on June 24, 2024

On the linked documentation page it literally says that this is expected:

Although in some cases React may still need to call your component before skipping the children, it shouldn’t affect your code

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brayanjeshua avatar brayanjeshua commented on June 24, 2024

It could be a joke but... Have you tried to remove the StictMode?

https://react.dev/reference/react/StrictMode

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alexreardon avatar alexreardon commented on June 24, 2024

I can confirm that this bug appears without strict mode on

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github-actions avatar github-actions commented on June 24, 2024

This issue has been automatically marked as stale. If this issue is still affecting you, please leave any comment (for example, "bump"), and we'll keep it open. We are sorry that we haven't been able to prioritize it yet. If you have any new additional information, please include it with your comment!

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github-actions avatar github-actions commented on June 24, 2024

Closing this issue after a prolonged period of inactivity. If this issue is still present in the latest release, please create a new issue with up-to-date information. Thank you!

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