[RN] Fix timeStamp property of SyntheticEvent in React Native#35912
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rubennorte merged 1 commit intofacebook:mainfrom Feb 26, 2026
Merged
[RN] Fix timeStamp property of SyntheticEvent in React Native#35912rubennorte merged 1 commit intofacebook:mainfrom
rubennorte merged 1 commit intofacebook:mainfrom
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javache
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## Summary This fixes the semantics of the `timeStamp` property of events in React Native. Currently, most events just assign `Date.now()` (at the time of creating the event object in JavaScript) as the `timeStamp` property. This is a divergence with Web and most native platforms, that use a monotonic timestamp for the value (on Web, the same timestamp provided by `performance.now()`). Additionally, many native events specify a timestamp in the event data object as `timestamp` and gets ignored by the logic in JS as it only looks at properties named `timeStamp` specifically (camel case). This PR fixes both issues by: 1. Using `performance.now()` instead of `Date.now()` by default (if available). 2. Checking for a `timestamp` property before falling back to the default (apart from `timeStamp`). ## How did you test this change? Added unit tests for verify the new behavior. DiffTrain build for [a48e9e3](a48e9e3)
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In StrictMode, `doubleInvokeEffectsInDEVIfNecessary` fires for any fiber that has the `PlacementDEV` flag set. Previously, `placeChild` set `PlacementDEV` on both newly inserted fibers AND fibers that were moved to a different position in an array. This caused a regression in React 19: when a keyed child is reordered within an array, its effects are re-run in dev/StrictMode even when dependencies are empty `[]`. The same component in production, or in React 18, correctly skips effect re-runs for moves. The fix is to only set `PlacementDEV` for actual insertions (where `current === null`). Moved fibers (`current !== null`, `oldIndex < lastPlacedIndex`) still receive the `Placement` flag so the host node is correctly repositioned in the DOM, but StrictMode no longer treats them as new mounts. Also fix unused `ref3` variable in ReactFabric-test.internal.js introduced in facebook#35912 (copy-paste: third View used ref2 instead of ref3). Fixes facebook#32561
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…Native (#35947) ## Summary This defines the same fiber configuration for RN as used in DOM, so we can expose event timing information in the React scheduler tracks in performance traces. This was unblocked by #35913 and #35912. ## How did you test this change? Manually compiled the renderer and tested e2e in FB infra: <img width="1217" height="161" alt="Screenshot 2026-03-03 at 10 10 44" src="https://github.com/user-attachments/assets/6ca1512e-dcaf-49cf-8da9-1c6ae554733a" />
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…Native (#35947) ## Summary This defines the same fiber configuration for RN as used in DOM, so we can expose event timing information in the React scheduler tracks in performance traces. This was unblocked by #35913 and #35912. ## How did you test this change? Manually compiled the renderer and tested e2e in FB infra: <img width="1217" height="161" alt="Screenshot 2026-03-03 at 10 10 44" src="https://github.com/user-attachments/assets/6ca1512e-dcaf-49cf-8da9-1c6ae554733a" /> DiffTrain build for [4cc5b7a](4cc5b7a)
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…Native (facebook#35947) ## Summary This defines the same fiber configuration for RN as used in DOM, so we can expose event timing information in the React scheduler tracks in performance traces. This was unblocked by facebook#35913 and facebook#35912. ## How did you test this change? Manually compiled the renderer and tested e2e in FB infra: <img width="1217" height="161" alt="Screenshot 2026-03-03 at 10 10 44" src="https://github.com/user-attachments/assets/6ca1512e-dcaf-49cf-8da9-1c6ae554733a" /> DiffTrain build for [4cc5b7a](facebook@4cc5b7a)
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…Native (facebook#35947) ## Summary This defines the same fiber configuration for RN as used in DOM, so we can expose event timing information in the React scheduler tracks in performance traces. This was unblocked by facebook#35913 and facebook#35912. ## How did you test this change? Manually compiled the renderer and tested e2e in FB infra: <img width="1217" height="161" alt="Screenshot 2026-03-03 at 10 10 44" src="https://github.com/user-attachments/assets/6ca1512e-dcaf-49cf-8da9-1c6ae554733a" /> DiffTrain build for [4cc5b7a](facebook@4cc5b7a)
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Summary
This fixes the semantics of the
timeStampproperty of events in React Native.Currently, most events just assign
Date.now()(at the time of creating the event object in JavaScript) as thetimeStampproperty. This is a divergence with Web and most native platforms, that use a monotonic timestamp for the value (on Web, the same timestamp provided byperformance.now()).Additionally, many native events specify a timestamp in the event data object as
timestampand gets ignored by the logic in JS as it only looks at properties namedtimeStampspecifically (camel case).This PR fixes both issues by:
performance.now()instead ofDate.now()by default (if available).timestampproperty before falling back to the default (apart fromtimeStamp).How did you test this change?
Added unit tests for verify the new behavior.