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fix: initialize transition start time with performance.now() #35726

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fix: initialize transition start time with performance.now() #35726

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4add586
fix: initialize transition start time with performance.now()
subhamkumarr Feb 8, 2026
13712bc
style: fix whitespace and formatting to minimize diff
subhamkumarr Feb 8, 2026
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4 changes: 0 additions & 4 deletions packages/react-reconciler/src/ReactFiberWorkLoop.js
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Original file line number Diff line number Diff line change
Expand Up @@ -1036,10 +1036,6 @@ export function scheduleUpdateOnFiber(
if (enableTransitionTracing) {
const transition = ReactSharedInternals.T;
if (transition !== null && transition.name != null) {
if (transition.startTime === -1) {
transition.startTime = now();
}

addTransitionToLanesMap(root, transition, lane);
}
}
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10 changes: 8 additions & 2 deletions packages/react/src/ReactStartTransition.js
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Original file line number Diff line number Diff line change
Expand Up @@ -42,6 +42,12 @@ function releaseAsyncTransition() {
}
}


const now =
typeof performance === 'object' && typeof performance.now === 'function'
? () => performance.now()
: () => Date.now();

export function startTransition(
scope: () => void,
options?: StartTransitionOptions,
Expand All @@ -65,7 +71,7 @@ export function startTransition(
if (enableTransitionTracing) {
currentTransition.name =
options !== undefined && options.name !== undefined ? options.name : null;
currentTransition.startTime = -1; // TODO: This should read the timestamp.
currentTransition.startTime = now();
}
if (__DEV__) {
currentTransition._updatedFibers = new Set();
Expand Down Expand Up @@ -146,7 +152,7 @@ export function startGestureTransition(
if (enableTransitionTracing) {
currentTransition.name =
options !== undefined && options.name !== undefined ? options.name : null;
currentTransition.startTime = -1; // TODO: This should read the timestamp.
currentTransition.startTime = now();
}
if (__DEV__) {
currentTransition._updatedFibers = new Set();
Expand Down