fix: make useThrottle resilient to remounting#42
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deltaidea wants to merge 1 commit intoEricLambrecht:mainfrom
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fix: make useThrottle resilient to remounting#42deltaidea wants to merge 1 commit intoEricLambrecht:mainfrom
deltaidea wants to merge 1 commit intoEricLambrecht:mainfrom
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The cleanup function cleared the timeout without resetting the timeout ref, so in strict mode (or in general when React calls cleanup but then ends up not unmounting) the effect would get stuck, never actually calling the callback. See: https://react.dev/learn/lifecycle-of-reactive-effects#how-react-verifies-that-your-effect-can-re-synchronize
EricLambrecht
requested changes
Jan 8, 2026
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Thank you for filing this pull request! I very much appreciate it. I have one suggested change, to have more coverage. My suggestions seem to work with your fix. Also, please rebase on main. Thanks! :)
Edit: I just noticed, that useDebounce will probably face the same issue. If you want to, you can fix it, too!
| jest.runAllTimers() | ||
| }) | ||
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| expect(timeoutHandler).toHaveBeenCalledTimes(1) |
Owner
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Suggested change
| expect(timeoutHandler).toHaveBeenCalledTimes(1) | |
| expect(timeoutHandler).toHaveBeenCalledTimes(1) | |
| expect(clearTimeoutSpy).toHaveBeenCalledTimes(1) |
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I suggest that we test both the execution and cleanup call in both new and old tests.
| @@ -232,6 +232,26 @@ describe('useThrottle', () => { | |||
| expect(clearTimeoutSpy).toHaveBeenCalledTimes(1) | |||
Owner
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Suggested change
| expect(clearTimeoutSpy).toHaveBeenCalledTimes(1) | |
| expect(timeoutHandler).toHaveBeenCalledTimes(1) | |
| expect(clearTimeoutSpy).toHaveBeenCalledTimes(1) |
See my other comment at L252
| "@shopify/jest-dom-mocks": "^5.2.0", | ||
| "@testing-library/jest-dom": "^6.5.0", | ||
| "@testing-library/react": "^16.0.1", | ||
| "@testing-library/react": "^16.3.1", |
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I recently updated the testing library packages, so this is now obsolete.
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The cleanup function cleared the timeout without resetting the timeout ref, so in strict mode (or in general when React calls cleanup but then ends up not unmounting) the effect would get stuck, never actually calling the callback.
See: https://react.dev/learn/lifecycle-of-reactive-effects#how-react-verifies-that-your-effect-can-re-synchronize
I've encountered this bug while using Next.js in watch mode. Happy I could track it down to the root cause.
The additional unit test fails without the proposed change.