Move update scheduling to microtask #26512
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Comparing: 8310854...5c1cf56 Critical size changesIncludes critical production bundles, as well as any change greater than 2%:
Significant size changesIncludes any change greater than 0.2%: Expand to show
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acdlite
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Mar 29, 2023
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| let isFlushingWork: boolean = false; | ||
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| export function ensureRootIsScheduled(root: FiberRoot): void { |
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This looks like a bunch of new code but it's less new than it looks.
This module replaces the ReactFiberSyncTaskQueue module that existed previously. Instead of being a generic callback queue, we now maintain a list of all the FiberRoots that have work schedule on them. This was effectively what we were already doing because the only type of callback that was ever scheduled was performSyncWorkOnRoot.
Then, since we have a list of roots with pending work, I also use that same data structure to stash the root until the microtask where we can do our scheduling logic. So I moved ensureRootIsScheduled (where most of that logic lives) into this file to try to keep it all colocated.
I originally was just going to dump this all into the work loop module but there's enough going on here that I think it merits its own module. The way I think of it is that the work loop contains all the logic for a particular render + commit phase, and this module is about scheduling those render cycles with the host environment.
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The best way to review this PR is probably to read this module from top to bottom, keeping in mind that most of it isn't actually new but is ported from the previous implementation.
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Mar 30, 2023
| } | ||
| root = root.next; | ||
| } | ||
| } while (didPerformSomeWork); |
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Do we need this outer loop because inner loop can schedule new work?
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Yeah completing one sync task might spawn additional sync tasks so we keep checking until there's nothing left
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| // Add the root to the schedule | ||
| if (root === lastScheduledRoot || root.next !== null) { | ||
| // Fast path. This root is already scheduled. |
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No because even if a root is scheduled its priority might have changed so we still need to process it in the microtask
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| if ( | ||
| newCallbackPriority === existingCallbackPriority && |
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This moved after the includesSyncLane check compared to the old version. Does this condition no longer apply when includesSyncLane?
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It didn't apply previously either because sync tasks don't get canceled, so I moved it into this more specific branch
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Doesn't this mean that when we have a task scheduled, and then sync work comes in, we wont cancel the first task anymore?
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Yeah that's true, though canceling the callback is really just a perf optimization in that case because the extra callback will immediately exit. Though I suppose that's reason enough to move this back to the common path.
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Ended up adding a separate cancelCallback in that path since it doesn't need the priority check
| @@ -963,7 +963,7 @@ describe('ProfilingCache', () => { | |||
| 2 => 0, | |||
| }, | |||
| "passiveEffectDuration": null, | |||
| "priorityLevel": "Immediate", | |||
| "priorityLevel": "Normal", | |||
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Why did the value change here?
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The Suspense retry runs in a microtask now instead of an Immediate Scheduler task. This is an implementation detail so it doesn't matter.
Yeah probably should because it will likely break the www Relay tests, and maybe some other older tests in www that don't use |
It doesn't have much benefit on its own, except for when you have a single event handler that calls setState many times repeatedly, like in a Flux implementation. Which is more common for older React apps, like Ads Manager. The main benefit is it makes future projects like sync unification easier because we can put more logic into the microtask phase. |
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rickhanlonii
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Mar 30, 2023
| }); | ||
| } | ||
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| // TODO: Can we land supportsMicrotasks? Which environments don't support it? |
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I don't think so, React Native does not support microtasks. Hermes is working on it, but it doesn't exist in JSC. If we moved this to the host config, then RN could probably do a user-land fallback for JSC if microtasks were not available. I think I originally had it layered so it was all in the host config so +1.
Previous discussion here: #20658
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I think we could argue that Immediate tasks should run before microtasks, which is essentially the only way we use the immediate priority now, so you could argue this belongs in the Scheduler :)
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Ok I'll just leave this as-is for now then
| // Alternatively, can we move this check to the host config? | ||
| if (supportsMicrotasks) { | ||
| scheduleMicrotask(() => { | ||
| // In Safari, appending an iframe forces microtasks to run. |
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Is this a problem if we're already in a microtask?
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That's why line 456 schedules a Scheduler task instead of a microtask, to prevent a potential loop
| if ((executionContext & (RenderContext | CommitContext)) === NoContext) { | ||
| resetRenderTimer(); | ||
| // TODO: For historical reasons this flushes all sync work across all | ||
| // roots. It shouldn't really matter either way, but we could change this | ||
| // to only flush the given root. |
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I may misunderstand when this happens, but would this matter for RN where multiple roots is common? e.g. the pre-rendering case? Is there a test for this I can look at?
| additionalLogsAfterAttemptingToYield: ['C', 'D'], | ||
| }); | ||
| await waitFor(['B']); | ||
| await waitForAll(['C', 'D']); |
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| if ( | ||
| newCallbackPriority === existingCallbackPriority && |
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Doesn't this mean that when we have a task scheduled, and then sync work comes in, we wont cancel the first task anymore?
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This moves a special check related to `act` in the legacy renderer. I moved it out of the `ensureRootIsScheduled` path and into `scheduleUpdateOnFiber`. There's some related logic that's already there and it makes sense to keep them together. Pure refactor, no behavior change.
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When React receives new input (via `setState`, a Suspense promise resolution, and so on), it needs to ensure there's a rendering task associated with the update. Most of this happens `ensureRootIsScheduled`. If a single event contains multiple updates, we end up running the scheduling code once per update. But this is wasteful because we really only need to run it once, at the end of the event (or in the case of flushSync, at the end of the scope function's execution). So this PR moves the scheduling logic to happen in a microtask instead. In some cases, we will force it run earlier than that, like for `flushSync`, but since updates are batched by default, it will almost always happen in the microtask. Even for discrete updates. In production, this should have no observable behavior difference. In a testing environment that uses `act`, this should also not have a behavior difference because React will push these tasks to an internal `act` queue. However, tests that do not use `act` and do not simulate an actual production environment (like an e2e test) may be affected. For example, before this change, if a test were to call `setState` outside of `act` and then immediately call `jest.runAllTimers()`, the update would be synchronously applied. After this change, that will no longer work because the rendering task (a timer, in this case) isn't scheduled until after the microtask queue has run. I don't expect this to be an issue in practice because most people do not write their tests this way. They either use `act`, or they write e2e-style tests. The biggest exception has been... our own internal test suite. Until recently, many of our tests were written in a way that accidentally relied on the updates being scheduled synchronously. Over the past few weeks, @tyao1 and I have gradually converted the test suite to use a new set of testing helpers that are resilient to this implementation detail. (There are also some old Relay tests that were written in the style of React's internal test suite. Those will need to be fixed, too.) The larger motivation behind this change, aside from a minor performance improvement, is we intend to use this new microtask to perform additional logic that doesn't yet exist. Like inferring the priority of a custom event.
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When React receives new input (via `setState`, a Suspense promise resolution, and so on), it needs to ensure there's a rendering task associated with the update. Most of this happens `ensureRootIsScheduled`. If a single event contains multiple updates, we end up running the scheduling code once per update. But this is wasteful because we really only need to run it once, at the end of the event (or in the case of flushSync, at the end of the scope function's execution). So this PR moves the scheduling logic to happen in a microtask instead. In some cases, we will force it run earlier than that, like for `flushSync`, but since updates are batched by default, it will almost always happen in the microtask. Even for discrete updates. In production, this should have no observable behavior difference. In a testing environment that uses `act`, this should also not have a behavior difference because React will push these tasks to an internal `act` queue. However, tests that do not use `act` and do not simulate an actual production environment (like an e2e test) may be affected. For example, before this change, if a test were to call `setState` outside of `act` and then immediately call `jest.runAllTimers()`, the update would be synchronously applied. After this change, that will no longer work because the rendering task (a timer, in this case) isn't scheduled until after the microtask queue has run. I don't expect this to be an issue in practice because most people do not write their tests this way. They either use `act`, or they write e2e-style tests. The biggest exception has been... our own internal test suite. Until recently, many of our tests were written in a way that accidentally relied on the updates being scheduled synchronously. Over the past few weeks, @tyao1 and I have gradually converted the test suite to use a new set of testing helpers that are resilient to this implementation detail. (There are also some old Relay tests that were written in the style of React's internal test suite. Those will need to be fixed, too.) The larger motivation behind this change, aside from a minor performance improvement, is we intend to use this new microtask to perform additional logic that doesn't yet exist. Like inferring the priority of a custom event. DiffTrain build for [09c8d25](09c8d25)
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`act` uses the `didScheduleLegacyUpdate` field to simulate the behavior of batching in React <17 and below. It's a quirk leftover from a previous implementation, not intentionally designed. This sets `didScheduleLegacyUpdate` every time a legacy root receives an update as opposed to only when the `executionContext` is empty. There's no real reason to do it this way over some other way except that it's how it used to work before facebook#26512 and we should try our best to maintain the existing behavior, quirks and all, since existing tests may have come to accidentally rely on it. This should fix some (though not all) of the internal Meta tests that started failing after facebook#26512 landed.
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`act` uses the `didScheduleLegacyUpdate` field to simulate the behavior of batching in React <17 and below. It's a quirk leftover from a previous implementation, not intentionally designed. This sets `didScheduleLegacyUpdate` every time a legacy root receives an update as opposed to only when the `executionContext` is empty. There's no real reason to do it this way over some other way except that it's how it used to work before facebook#26512 and we should try our best to maintain the existing behavior, quirks and all, since existing tests may have come to accidentally rely on it. This should fix some (though not all) of the internal Meta tests that started failing after facebook#26512 landed.
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`act` uses the `didScheduleLegacyUpdate` field to simulate the behavior of batching in React <17 and below. It's a quirk leftover from a previous implementation, not intentionally designed. This sets `didScheduleLegacyUpdate` every time a legacy root receives an update as opposed to only when the `executionContext` is empty. There's no real reason to do it this way over some other way except that it's how it used to work before facebook#26512 and we should try our best to maintain the existing behavior, quirks and all, since existing tests may have come to accidentally rely on it. This should fix some (though not all) of the internal Meta tests that started failing after facebook#26512 landed.
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`act` uses the `didScheduleLegacyUpdate` field to simulate the behavior of batching in React <17 and below. It's a quirk leftover from a previous implementation, not intentionally designed. This sets `didScheduleLegacyUpdate` every time a legacy root receives an update as opposed to only when the `executionContext` is empty. There's no real reason to do it this way over some other way except that it's how it used to work before facebook#26512 and we should try our best to maintain the existing behavior, quirks and all, since existing tests may have come to accidentally rely on it. This should fix some (though not all) of the internal Meta tests that started failing after facebook#26512 landed.
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`act` uses the `didScheduleLegacyUpdate` field to simulate the behavior of batching in React <17 and below. It's a quirk leftover from a previous implementation, not intentionally designed. This sets `didScheduleLegacyUpdate` every time a legacy root receives an update as opposed to only when the `executionContext` is empty. There's no real reason to do it this way over some other way except that it's how it used to work before #26512 and we should try our best to maintain the existing behavior, quirks and all, since existing tests may have come to accidentally rely on it. This should fix some (though not all) of the internal Meta tests that started failing after #26512 landed. Will add a regression test before merging.
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`act` uses the `didScheduleLegacyUpdate` field to simulate the behavior of batching in React <17 and below. It's a quirk leftover from a previous implementation, not intentionally designed. This sets `didScheduleLegacyUpdate` every time a legacy root receives an update as opposed to only when the `executionContext` is empty. There's no real reason to do it this way over some other way except that it's how it used to work before #26512 and we should try our best to maintain the existing behavior, quirks and all, since existing tests may have come to accidentally rely on it. This should fix some (though not all) of the internal Meta tests that started failing after #26512 landed. Will add a regression test before merging. DiffTrain build for [fec97ec](fec97ec)
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Summary: This sync includes the following changes: - **[58742c21b](facebook/react@58742c21b )**: Delete unused `eventTimes` Fiber field ([#26599](facebook/react#26599)) //<Andrew Clark>// - **[0b931f90e](facebook/react@0b931f90e )**: Remove JND delay for non-transition updates ([#26597](facebook/react#26597)) //<Andrew Clark>// - **[ac43bf687](facebook/react@ac43bf687 )**: Move validation of text nesting into ReactDOMComponent ([#26594](facebook/react#26594)) //<Sebastian Markbåge>// - **[ca41adb8c](facebook/react@ca41adb8c )**: Diff properties in the commit phase instead of generating an update payload ([#26583](facebook/react#26583)) //<Sebastian Markbåge>// - **[dd0619b2e](facebook/react@dd0619b2e )**: rename $$$hostConfig to $$$config ([#26593](facebook/react#26593)) //<Josh Story>// - **[b55d31955](facebook/react@b55d31955 )**: Rename HostConfig files to FiberConfig to clarify they are configs fo… ([#26592](facebook/react#26592)) //<Josh Story>// - **[ffb8eaca5](facebook/react@ffb8eaca5 )**: Rename ReactServerFormatConfig to ReactFizzConfig ([#26591](facebook/react#26591)) //<Josh Story>// - **[f4f873f62](facebook/react@f4f873f62 )**: Implements wiring for Flight to have it's own "HostConfig" ([#26590](facebook/react#26590)) //<Josh Story>// - **[44db16afc](facebook/react@44db16afc )**: Normalize ReactFlightServerConfig and related files ([#26589](facebook/react#26589)) //<Josh Story>// - **[fec97ecbc](facebook/react@fec97ecbc )**: act: Move didScheduleLegacyUpdate to ensureRootIsScheduled ([#26552](facebook/react#26552)) //<Andrew Clark>// - **[9a9da7721](facebook/react@9a9da7721 )**: Don't update textarea defaultValue and input checked unnecessarily ([#26580](facebook/react#26580)) //<Sebastian Markbåge>// - **[e5146cb52](facebook/react@e5146cb52 )**: Refactor some controlled component stuff ([#26573](facebook/react#26573)) //<Sebastian Markbåge>// - **[657698e48](facebook/react@657698e48 )**: [Tests] `waitForThrow` should diff strings ([#26568](facebook/react#26568)) //<Josh Story>// - **[85bb7b685](facebook/react@85bb7b685 )**: Fix: Move `destroy` field to shared instance object ([#26561](facebook/react#26561)) //<Andrew Clark>// - **[9cfba0f6e](facebook/react@9cfba0f6e )**: Clean up discrete event replaying ([#26558](facebook/react#26558)) //<Sebastian Markbåge>// - **[790ebc962](facebook/react@790ebc962 )**: Remove no-fallthrough lint suppressions ([#26553](facebook/react#26553)) //<Sophie Alpert>// - **[c15579631](facebook/react@c15579631 )**: Put common aliases in Map/Set instead of switch over strings ([#26551](facebook/react#26551)) //<Sebastian Markbåge>// - **[d5fd60f7e](facebook/react@d5fd60f7e )**: Remove findInstanceBlockingEvent unused parameters ([#26534](facebook/react#26534)) //<Mohammad Ghorbani>// - **[eeabb7312](facebook/react@eeabb7312 )**: Refactor DOM Bindings Completely Off of DOMProperty Meta Programming ([#26546](facebook/react#26546)) //<Sebastian Markbåge>// - **[da94e8b24](facebook/react@da94e8b24 )**: Revert "Cleanup enableSyncDefaultUpdate flag ([#26236](facebook/react#26236))" ([#26528](facebook/react#26528)) //<Jan Kassens>// - **[0700dd50b](facebook/react@0700dd50b )**: Implement public instances for text nodes in Fabric ([#26516](facebook/react#26516)) //<Rubén Norte>// - **[4a1cc2ddd](facebook/react@4a1cc2ddd )**: Fix logic around attribute seralization ([#26526](facebook/react#26526)) //<Josh Story>// - **[7329ea81c](facebook/react@7329ea81c )**: Fix suspense replaying forward refs ([#26535](facebook/react#26535)) //<Hans Otto Wirtz>// - **[0ae348018](facebook/react@0ae348018 )**: [Float] Suspend unstyled content for up to 1 minute ([#26532](facebook/react#26532)) //<Andrew Clark>// - **[888874673](facebook/react@888874673 )**: Allow transitions to interrupt Suspensey commits ([#26531](facebook/react#26531)) //<Andrew Clark>// - **[09c8d2563](facebook/react@09c8d2563 )**: Move update scheduling to microtask ([#26512](facebook/react#26512)) //<Andrew Clark>// - **[8310854ce](facebook/react@8310854ce )**: Clean up enableCapturePhaseSelectiveHydrationWithoutDiscreteEventReplay ([#26521](facebook/react#26521)) //<Andrew Clark>// Changelog: [General][Changed] - React Native sync for revisions ca01f35...58742c2 jest_e2e[run_all_tests] bypass-github-export-checks Reviewed By: sammy-SC Differential Revision: D44872333 fbshipit-source-id: 0695e86645955aac7a20afdaf3ed02ad33592f5c
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Full list of changes (not everything included in changelog): * refactor[devtools]: copy to clipboard only on frontend side ([hoxyq](https://github.com/hoxyq) in [#26604](#26604)) * Provide icon to edge devtools. ([harrygz889](https://github.com/harrygz889) in [#26543](#26543)) * [BE] move shared types & constants to consolidated locations ([mondaychen](https://github.com/mondaychen) in [#26572](#26572)) * remove backend dependency from the global hook ([mondaychen](https://github.com/mondaychen) in [#26563](#26563)) * Replace deprecated `new-window` with `webContents.setWindowOpenHandler()` ([Willie-Boy](https://github.com/Willie-Boy) in [#26559](#26559)) * DevTools: Inline references to fiber flags ([acdlite](https://github.com/acdlite) in [#26542](#26542)) * refactor[devtools]: forbid editing class instances in props ([hoxyq](https://github.com/hoxyq) in [#26522](#26522)) * Move update scheduling to microtask ([acdlite](https://github.com/acdlite) in [#26512](#26512)) * Remove unnecessary CIRCLE_CI_API_TOKEN checks ([mondaychen](https://github.com/mondaychen) in [#26499](#26499)) * browser extension: improve script injection logic ([mondaychen](https://github.com/mondaychen) in [#26492](#26492)) * [flow] make Flow suppressions explicit on the error ([kassens](https://github.com/kassens) in [#26487](#26487))
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Full list of changes (not everything included in changelog): * refactor[devtools]: copy to clipboard only on frontend side ([hoxyq](https://github.com/hoxyq) in [facebook#26604](facebook#26604)) * Provide icon to edge devtools. ([harrygz889](https://github.com/harrygz889) in [facebook#26543](facebook#26543)) * [BE] move shared types & constants to consolidated locations ([mondaychen](https://github.com/mondaychen) in [facebook#26572](facebook#26572)) * remove backend dependency from the global hook ([mondaychen](https://github.com/mondaychen) in [facebook#26563](facebook#26563)) * Replace deprecated `new-window` with `webContents.setWindowOpenHandler()` ([Willie-Boy](https://github.com/Willie-Boy) in [facebook#26559](facebook#26559)) * DevTools: Inline references to fiber flags ([acdlite](https://github.com/acdlite) in [facebook#26542](facebook#26542)) * refactor[devtools]: forbid editing class instances in props ([hoxyq](https://github.com/hoxyq) in [facebook#26522](facebook#26522)) * Move update scheduling to microtask ([acdlite](https://github.com/acdlite) in [facebook#26512](facebook#26512)) * Remove unnecessary CIRCLE_CI_API_TOKEN checks ([mondaychen](https://github.com/mondaychen) in [facebook#26499](facebook#26499)) * browser extension: improve script injection logic ([mondaychen](https://github.com/mondaychen) in [facebook#26492](facebook#26492)) * [flow] make Flow suppressions explicit on the error ([kassens](https://github.com/kassens) in [facebook#26487](facebook#26487))
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This reverts commit 09c8d25.
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May 7, 2023
Summary: This sync includes the following changes: - **[58742c21b](facebook/react@58742c21b )**: Delete unused `eventTimes` Fiber field ([facebook#26599](facebook/react#26599)) //<Andrew Clark>// - **[0b931f90e](facebook/react@0b931f90e )**: Remove JND delay for non-transition updates ([facebook#26597](facebook/react#26597)) //<Andrew Clark>// - **[ac43bf687](facebook/react@ac43bf687 )**: Move validation of text nesting into ReactDOMComponent ([facebook#26594](facebook/react#26594)) //<Sebastian Markbåge>// - **[ca41adb8c](facebook/react@ca41adb8c )**: Diff properties in the commit phase instead of generating an update payload ([facebook#26583](facebook/react#26583)) //<Sebastian Markbåge>// - **[dd0619b2e](facebook/react@dd0619b2e )**: rename $$$hostConfig to $$$config ([facebook#26593](facebook/react#26593)) //<Josh Story>// - **[b55d31955](facebook/react@b55d31955 )**: Rename HostConfig files to FiberConfig to clarify they are configs fo… ([facebook#26592](facebook/react#26592)) //<Josh Story>// - **[ffb8eaca5](facebook/react@ffb8eaca5 )**: Rename ReactServerFormatConfig to ReactFizzConfig ([facebook#26591](facebook/react#26591)) //<Josh Story>// - **[f4f873f62](facebook/react@f4f873f62 )**: Implements wiring for Flight to have it's own "HostConfig" ([facebook#26590](facebook/react#26590)) //<Josh Story>// - **[44db16afc](facebook/react@44db16afc )**: Normalize ReactFlightServerConfig and related files ([facebook#26589](facebook/react#26589)) //<Josh Story>// - **[fec97ecbc](facebook/react@fec97ecbc )**: act: Move didScheduleLegacyUpdate to ensureRootIsScheduled ([facebook#26552](facebook/react#26552)) //<Andrew Clark>// - **[9a9da7721](facebook/react@9a9da7721 )**: Don't update textarea defaultValue and input checked unnecessarily ([facebook#26580](facebook/react#26580)) //<Sebastian Markbåge>// - **[e5146cb52](facebook/react@e5146cb52 )**: Refactor some controlled component stuff ([facebook#26573](facebook/react#26573)) //<Sebastian Markbåge>// - **[657698e48](facebook/react@657698e48 )**: [Tests] `waitForThrow` should diff strings ([facebook#26568](facebook/react#26568)) //<Josh Story>// - **[85bb7b685](facebook/react@85bb7b685 )**: Fix: Move `destroy` field to shared instance object ([facebook#26561](facebook/react#26561)) //<Andrew Clark>// - **[9cfba0f6e](facebook/react@9cfba0f6e )**: Clean up discrete event replaying ([facebook#26558](facebook/react#26558)) //<Sebastian Markbåge>// - **[790ebc962](facebook/react@790ebc962 )**: Remove no-fallthrough lint suppressions ([facebook#26553](facebook/react#26553)) //<Sophie Alpert>// - **[c15579631](facebook/react@c15579631 )**: Put common aliases in Map/Set instead of switch over strings ([facebook#26551](facebook/react#26551)) //<Sebastian Markbåge>// - **[d5fd60f7e](facebook/react@d5fd60f7e )**: Remove findInstanceBlockingEvent unused parameters ([facebook#26534](facebook/react#26534)) //<Mohammad Ghorbani>// - **[eeabb7312](facebook/react@eeabb7312 )**: Refactor DOM Bindings Completely Off of DOMProperty Meta Programming ([facebook#26546](facebook/react#26546)) //<Sebastian Markbåge>// - **[da94e8b24](facebook/react@da94e8b24 )**: Revert "Cleanup enableSyncDefaultUpdate flag ([facebook#26236](facebook/react#26236))" ([facebook#26528](facebook/react#26528)) //<Jan Kassens>// - **[0700dd50b](facebook/react@0700dd50b )**: Implement public instances for text nodes in Fabric ([facebook#26516](facebook/react#26516)) //<Rubén Norte>// - **[4a1cc2ddd](facebook/react@4a1cc2ddd )**: Fix logic around attribute seralization ([facebook#26526](facebook/react#26526)) //<Josh Story>// - **[7329ea81c](facebook/react@7329ea81c )**: Fix suspense replaying forward refs ([facebook#26535](facebook/react#26535)) //<Hans Otto Wirtz>// - **[0ae348018](facebook/react@0ae348018 )**: [Float] Suspend unstyled content for up to 1 minute ([facebook#26532](facebook/react#26532)) //<Andrew Clark>// - **[888874673](facebook/react@888874673 )**: Allow transitions to interrupt Suspensey commits ([facebook#26531](facebook/react#26531)) //<Andrew Clark>// - **[09c8d2563](facebook/react@09c8d2563 )**: Move update scheduling to microtask ([facebook#26512](facebook/react#26512)) //<Andrew Clark>// - **[8310854ce](facebook/react@8310854ce )**: Clean up enableCapturePhaseSelectiveHydrationWithoutDiscreteEventReplay ([facebook#26521](facebook/react#26521)) //<Andrew Clark>// Changelog: [General][Changed] - React Native sync for revisions ca01f35...58742c2 jest_e2e[run_all_tests] bypass-github-export-checks Reviewed By: sammy-SC Differential Revision: D44872333 fbshipit-source-id: 0695e86645955aac7a20afdaf3ed02ad33592f5c
OlimpiaZurek
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May 22, 2023
Summary: This sync includes the following changes: - **[58742c21b](facebook/react@58742c21b )**: Delete unused `eventTimes` Fiber field ([facebook#26599](facebook/react#26599)) //<Andrew Clark>// - **[0b931f90e](facebook/react@0b931f90e )**: Remove JND delay for non-transition updates ([facebook#26597](facebook/react#26597)) //<Andrew Clark>// - **[ac43bf687](facebook/react@ac43bf687 )**: Move validation of text nesting into ReactDOMComponent ([facebook#26594](facebook/react#26594)) //<Sebastian Markbåge>// - **[ca41adb8c](facebook/react@ca41adb8c )**: Diff properties in the commit phase instead of generating an update payload ([facebook#26583](facebook/react#26583)) //<Sebastian Markbåge>// - **[dd0619b2e](facebook/react@dd0619b2e )**: rename $$$hostConfig to $$$config ([facebook#26593](facebook/react#26593)) //<Josh Story>// - **[b55d31955](facebook/react@b55d31955 )**: Rename HostConfig files to FiberConfig to clarify they are configs fo… ([facebook#26592](facebook/react#26592)) //<Josh Story>// - **[ffb8eaca5](facebook/react@ffb8eaca5 )**: Rename ReactServerFormatConfig to ReactFizzConfig ([facebook#26591](facebook/react#26591)) //<Josh Story>// - **[f4f873f62](facebook/react@f4f873f62 )**: Implements wiring for Flight to have it's own "HostConfig" ([facebook#26590](facebook/react#26590)) //<Josh Story>// - **[44db16afc](facebook/react@44db16afc )**: Normalize ReactFlightServerConfig and related files ([facebook#26589](facebook/react#26589)) //<Josh Story>// - **[fec97ecbc](facebook/react@fec97ecbc )**: act: Move didScheduleLegacyUpdate to ensureRootIsScheduled ([facebook#26552](facebook/react#26552)) //<Andrew Clark>// - **[9a9da7721](facebook/react@9a9da7721 )**: Don't update textarea defaultValue and input checked unnecessarily ([facebook#26580](facebook/react#26580)) //<Sebastian Markbåge>// - **[e5146cb52](facebook/react@e5146cb52 )**: Refactor some controlled component stuff ([facebook#26573](facebook/react#26573)) //<Sebastian Markbåge>// - **[657698e48](facebook/react@657698e48 )**: [Tests] `waitForThrow` should diff strings ([facebook#26568](facebook/react#26568)) //<Josh Story>// - **[85bb7b685](facebook/react@85bb7b685 )**: Fix: Move `destroy` field to shared instance object ([facebook#26561](facebook/react#26561)) //<Andrew Clark>// - **[9cfba0f6e](facebook/react@9cfba0f6e )**: Clean up discrete event replaying ([facebook#26558](facebook/react#26558)) //<Sebastian Markbåge>// - **[790ebc962](facebook/react@790ebc962 )**: Remove no-fallthrough lint suppressions ([facebook#26553](facebook/react#26553)) //<Sophie Alpert>// - **[c15579631](facebook/react@c15579631 )**: Put common aliases in Map/Set instead of switch over strings ([facebook#26551](facebook/react#26551)) //<Sebastian Markbåge>// - **[d5fd60f7e](facebook/react@d5fd60f7e )**: Remove findInstanceBlockingEvent unused parameters ([facebook#26534](facebook/react#26534)) //<Mohammad Ghorbani>// - **[eeabb7312](facebook/react@eeabb7312 )**: Refactor DOM Bindings Completely Off of DOMProperty Meta Programming ([facebook#26546](facebook/react#26546)) //<Sebastian Markbåge>// - **[da94e8b24](facebook/react@da94e8b24 )**: Revert "Cleanup enableSyncDefaultUpdate flag ([facebook#26236](facebook/react#26236))" ([facebook#26528](facebook/react#26528)) //<Jan Kassens>// - **[0700dd50b](facebook/react@0700dd50b )**: Implement public instances for text nodes in Fabric ([facebook#26516](facebook/react#26516)) //<Rubén Norte>// - **[4a1cc2ddd](facebook/react@4a1cc2ddd )**: Fix logic around attribute seralization ([facebook#26526](facebook/react#26526)) //<Josh Story>// - **[7329ea81c](facebook/react@7329ea81c )**: Fix suspense replaying forward refs ([facebook#26535](facebook/react#26535)) //<Hans Otto Wirtz>// - **[0ae348018](facebook/react@0ae348018 )**: [Float] Suspend unstyled content for up to 1 minute ([facebook#26532](facebook/react#26532)) //<Andrew Clark>// - **[888874673](facebook/react@888874673 )**: Allow transitions to interrupt Suspensey commits ([facebook#26531](facebook/react#26531)) //<Andrew Clark>// - **[09c8d2563](facebook/react@09c8d2563 )**: Move update scheduling to microtask ([facebook#26512](facebook/react#26512)) //<Andrew Clark>// - **[8310854ce](facebook/react@8310854ce )**: Clean up enableCapturePhaseSelectiveHydrationWithoutDiscreteEventReplay ([facebook#26521](facebook/react#26521)) //<Andrew Clark>// Changelog: [General][Changed] - React Native sync for revisions ca01f35...58742c2 jest_e2e[run_all_tests] bypass-github-export-checks Reviewed By: sammy-SC Differential Revision: D44872333 fbshipit-source-id: 0695e86645955aac7a20afdaf3ed02ad33592f5c
hoxyq
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that referenced
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Jun 26, 2023
…est (#27008) - Correctly gate the test to `[18.0.0, 18.2.0]` versions of react, as it was initially defined before #26742 - I have recently fixed the gating logic in #26955 and #26997, should be stable now - I have added a non-gated version of this test, which should run only for the current version of react, the one we build from sources - The test version for react `v[18.0.0, 18.2.0]` should expect `"priorityLevel": "Immediate"`, the other `"priorityLevel": "Normal"`, as it was changed in #26512
EdisonVan
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Apr 15, 2024
When React receives new input (via `setState`, a Suspense promise resolution, and so on), it needs to ensure there's a rendering task associated with the update. Most of this happens `ensureRootIsScheduled`. If a single event contains multiple updates, we end up running the scheduling code once per update. But this is wasteful because we really only need to run it once, at the end of the event (or in the case of flushSync, at the end of the scope function's execution). So this PR moves the scheduling logic to happen in a microtask instead. In some cases, we will force it run earlier than that, like for `flushSync`, but since updates are batched by default, it will almost always happen in the microtask. Even for discrete updates. In production, this should have no observable behavior difference. In a testing environment that uses `act`, this should also not have a behavior difference because React will push these tasks to an internal `act` queue. However, tests that do not use `act` and do not simulate an actual production environment (like an e2e test) may be affected. For example, before this change, if a test were to call `setState` outside of `act` and then immediately call `jest.runAllTimers()`, the update would be synchronously applied. After this change, that will no longer work because the rendering task (a timer, in this case) isn't scheduled until after the microtask queue has run. I don't expect this to be an issue in practice because most people do not write their tests this way. They either use `act`, or they write e2e-style tests. The biggest exception has been... our own internal test suite. Until recently, many of our tests were written in a way that accidentally relied on the updates being scheduled synchronously. Over the past few weeks, @tyao1 and I have gradually converted the test suite to use a new set of testing helpers that are resilient to this implementation detail. (There are also some old Relay tests that were written in the style of React's internal test suite. Those will need to be fixed, too.) The larger motivation behind this change, aside from a minor performance improvement, is we intend to use this new microtask to perform additional logic that doesn't yet exist. Like inferring the priority of a custom event.
EdisonVan
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to EdisonVan/react
that referenced
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Apr 15, 2024
…26552) `act` uses the `didScheduleLegacyUpdate` field to simulate the behavior of batching in React <17 and below. It's a quirk leftover from a previous implementation, not intentionally designed. This sets `didScheduleLegacyUpdate` every time a legacy root receives an update as opposed to only when the `executionContext` is empty. There's no real reason to do it this way over some other way except that it's how it used to work before facebook#26512 and we should try our best to maintain the existing behavior, quirks and all, since existing tests may have come to accidentally rely on it. This should fix some (though not all) of the internal Meta tests that started failing after facebook#26512 landed. Will add a regression test before merging.
EdisonVan
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Apr 15, 2024
Full list of changes (not everything included in changelog): * refactor[devtools]: copy to clipboard only on frontend side ([hoxyq](https://github.com/hoxyq) in [facebook#26604](facebook#26604)) * Provide icon to edge devtools. ([harrygz889](https://github.com/harrygz889) in [facebook#26543](facebook#26543)) * [BE] move shared types & constants to consolidated locations ([mondaychen](https://github.com/mondaychen) in [facebook#26572](facebook#26572)) * remove backend dependency from the global hook ([mondaychen](https://github.com/mondaychen) in [facebook#26563](facebook#26563)) * Replace deprecated `new-window` with `webContents.setWindowOpenHandler()` ([Willie-Boy](https://github.com/Willie-Boy) in [facebook#26559](facebook#26559)) * DevTools: Inline references to fiber flags ([acdlite](https://github.com/acdlite) in [facebook#26542](facebook#26542)) * refactor[devtools]: forbid editing class instances in props ([hoxyq](https://github.com/hoxyq) in [facebook#26522](facebook#26522)) * Move update scheduling to microtask ([acdlite](https://github.com/acdlite) in [facebook#26512](facebook#26512)) * Remove unnecessary CIRCLE_CI_API_TOKEN checks ([mondaychen](https://github.com/mondaychen) in [facebook#26499](facebook#26499)) * browser extension: improve script injection logic ([mondaychen](https://github.com/mondaychen) in [facebook#26492](facebook#26492)) * [flow] make Flow suppressions explicit on the error ([kassens](https://github.com/kassens) in [facebook#26487](facebook#26487))
EdisonVan
pushed a commit
to EdisonVan/react
that referenced
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Apr 15, 2024
…est (facebook#27008) - Correctly gate the test to `[18.0.0, 18.2.0]` versions of react, as it was initially defined before facebook#26742 - I have recently fixed the gating logic in facebook#26955 and facebook#26997, should be stable now - I have added a non-gated version of this test, which should run only for the current version of react, the one we build from sources - The test version for react `v[18.0.0, 18.2.0]` should expect `"priorityLevel": "Immediate"`, the other `"priorityLevel": "Normal"`, as it was changed in facebook#26512
bigfootjon
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that referenced
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Apr 18, 2024
When React receives new input (via `setState`, a Suspense promise resolution, and so on), it needs to ensure there's a rendering task associated with the update. Most of this happens `ensureRootIsScheduled`. If a single event contains multiple updates, we end up running the scheduling code once per update. But this is wasteful because we really only need to run it once, at the end of the event (or in the case of flushSync, at the end of the scope function's execution). So this PR moves the scheduling logic to happen in a microtask instead. In some cases, we will force it run earlier than that, like for `flushSync`, but since updates are batched by default, it will almost always happen in the microtask. Even for discrete updates. In production, this should have no observable behavior difference. In a testing environment that uses `act`, this should also not have a behavior difference because React will push these tasks to an internal `act` queue. However, tests that do not use `act` and do not simulate an actual production environment (like an e2e test) may be affected. For example, before this change, if a test were to call `setState` outside of `act` and then immediately call `jest.runAllTimers()`, the update would be synchronously applied. After this change, that will no longer work because the rendering task (a timer, in this case) isn't scheduled until after the microtask queue has run. I don't expect this to be an issue in practice because most people do not write their tests this way. They either use `act`, or they write e2e-style tests. The biggest exception has been... our own internal test suite. Until recently, many of our tests were written in a way that accidentally relied on the updates being scheduled synchronously. Over the past few weeks, @tyao1 and I have gradually converted the test suite to use a new set of testing helpers that are resilient to this implementation detail. (There are also some old Relay tests that were written in the style of React's internal test suite. Those will need to be fixed, too.) The larger motivation behind this change, aside from a minor performance improvement, is we intend to use this new microtask to perform additional logic that doesn't yet exist. Like inferring the priority of a custom event. DiffTrain build for commit 09c8d25.
bigfootjon
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that referenced
this pull request
Apr 18, 2024
`act` uses the `didScheduleLegacyUpdate` field to simulate the behavior of batching in React <17 and below. It's a quirk leftover from a previous implementation, not intentionally designed. This sets `didScheduleLegacyUpdate` every time a legacy root receives an update as opposed to only when the `executionContext` is empty. There's no real reason to do it this way over some other way except that it's how it used to work before #26512 and we should try our best to maintain the existing behavior, quirks and all, since existing tests may have come to accidentally rely on it. This should fix some (though not all) of the internal Meta tests that started failing after #26512 landed. Will add a regression test before merging. DiffTrain build for commit fec97ec.
Akshato07
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that referenced
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Feb 20, 2025
Full list of changes (not everything included in changelog): * refactor[devtools]: copy to clipboard only on frontend side ([hoxyq](https://github.com/hoxyq) in [#26604](facebook/react#26604)) * Provide icon to edge devtools. ([harrygz889](https://github.com/harrygz889) in [#26543](facebook/react#26543)) * [BE] move shared types & constants to consolidated locations ([mondaychen](https://github.com/mondaychen) in [#26572](facebook/react#26572)) * remove backend dependency from the global hook ([mondaychen](https://github.com/mondaychen) in [#26563](facebook/react#26563)) * Replace deprecated `new-window` with `webContents.setWindowOpenHandler()` ([Willie-Boy](https://github.com/Willie-Boy) in [#26559](facebook/react#26559)) * DevTools: Inline references to fiber flags ([acdlite](https://github.com/acdlite) in [#26542](facebook/react#26542)) * refactor[devtools]: forbid editing class instances in props ([hoxyq](https://github.com/hoxyq) in [#26522](facebook/react#26522)) * Move update scheduling to microtask ([acdlite](https://github.com/acdlite) in [#26512](facebook/react#26512)) * Remove unnecessary CIRCLE_CI_API_TOKEN checks ([mondaychen](https://github.com/mondaychen) in [#26499](facebook/react#26499)) * browser extension: improve script injection logic ([mondaychen](https://github.com/mondaychen) in [#26492](facebook/react#26492)) * [flow] make Flow suppressions explicit on the error ([kassens](https://github.com/kassens) in [#26487](facebook/react#26487)) DiffTrain build for commit facebook/react@77d3b02.
Akshato07
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Feb 20, 2025
…est (#27008) - Correctly gate the test to `[18.0.0, 18.2.0]` versions of react, as it was initially defined before facebook/react#26742 - I have recently fixed the gating logic in facebook/react#26955 and facebook/react#26997, should be stable now - I have added a non-gated version of this test, which should run only for the current version of react, the one we build from sources - The test version for react `v[18.0.0, 18.2.0]` should expect `"priorityLevel": "Immediate"`, the other `"priorityLevel": "Normal"`, as it was changed in facebook/react#26512 DiffTrain build for commit facebook/react@6aacd3f.
henriettelienrebnor
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Apr 23, 2025
<h3>Snyk has created this PR to upgrade react from 19.0.0 to
19.1.0.</h3>
:information_source: Keep your dependencies up-to-date. This makes it
easier to fix existing vulnerabilities and to more quickly identify and
fix newly disclosed vulnerabilities when they affect your project.
<hr/>
- The recommended version is **78 versions** ahead of your current
version.
- The recommended version was released **22 days ago**.
<details>
<summary><b>Release notes</b></summary>
<br/>
<details>
<summary>Package name: <b>react</b></summary>
<ul>
<li>
<b>19.1.0</b> - <a
href="https://redirect.github.com/facebook/react/releases/tag/v19.1.0">2025-03-28</a></br><h3>Owner
Stack</h3>
<p>An Owner Stack is a string representing the components that are
directly responsible for rendering a particular component. You can log
Owner Stacks when debugging or use Owner Stacks to enhance error
overlays or other development tools. Owner Stacks are only available in
development builds. Component Stacks in production are unchanged.</p>
<ul>
<li>An Owner Stack is a development-only stack trace that helps identify
which components are responsible for rendering a particular component.
An Owner Stack is distinct from a Component Stacks, which shows the
hierarchy of components leading to an error.</li>
<li>The <a href="https://react.dev/reference/react/captureOwnerStack"
rel="nofollow">captureOwnerStack API</a> is only available in
development mode and returns a Owner Stack, if available. The API can be
used to enhance error overlays or log component relationships when
debugging. <a
href="https://redirect.github.com/facebook/react/pull/29923"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/29923/hovercard">#29923</a>, <a
href="https://redirect.github.com/facebook/react/pull/32353"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/32353/hovercard">#32353</a>, <a
href="https://redirect.github.com/facebook/react/pull/30306"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/30306/hovercard">#30306</a>,<br>
<a href="https://redirect.github.com/facebook/react/pull/32538"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/32538/hovercard">#32538</a>, <a
href="https://redirect.github.com/facebook/react/pull/32529"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/32529/hovercard">#32529</a>, <a
href="https://redirect.github.com/facebook/react/pull/32538"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/32538/hovercard">#32538</a></li>
</ul>
<h3>React</h3>
<ul>
<li>Enhanced support for Suspense boundaries to be used anywhere,
including the client, server, and during hydration. <a
href="https://redirect.github.com/facebook/react/pull/32069"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/32069/hovercard">#32069</a>, <a
href="https://redirect.github.com/facebook/react/pull/32163"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/32163/hovercard">#32163</a>, <a
href="https://redirect.github.com/facebook/react/pull/32224"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/32224/hovercard">#32224</a>, <a
href="https://redirect.github.com/facebook/react/pull/32252"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/32252/hovercard">#32252</a></li>
<li>Reduced unnecessary client rendering through improved hydration
scheduling <a
href="https://redirect.github.com/facebook/react/pull/31751"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/31751/hovercard">#31751</a></li>
<li>Increased priority of client rendered Suspense boundaries <a
href="https://redirect.github.com/facebook/react/pull/31776"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/31776/hovercard">#31776</a></li>
<li>Fixed frozen fallback states by rendering unfinished Suspense
boundaries on the client. <a
href="https://redirect.github.com/facebook/react/pull/31620"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/31620/hovercard">#31620</a></li>
<li>Reduced garbage collection pressure by improving Suspense boundary
retries. <a href="https://redirect.github.com/facebook/react/pull/31667"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/31667/hovercard">#31667</a></li>
<li>Fixed erroneous “Waiting for Paint” log when the passive effect
phase was not delayed <a
href="https://redirect.github.com/facebook/react/pull/31526"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/31526/hovercard">#31526</a></li>
<li>Fixed a regression causing key warnings for flattened positional
children in development mode. <a
href="https://redirect.github.com/facebook/react/pull/32117"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/32117/hovercard">#32117</a></li>
<li>Updated <code>useId</code> to use valid CSS selectors, changing
format from <code>:r123:</code> to <code>«r123»</code>. <a
href="https://redirect.github.com/facebook/react/pull/32001"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/32001/hovercard">#32001</a></li>
<li>Added a dev-only warning for null/undefined created in useEffect,
useInsertionEffect, and useLayoutEffect. <a
href="https://redirect.github.com/facebook/react/pull/32355"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/32355/hovercard">#32355</a></li>
<li>Fixed a bug where dev-only methods were exported in production
builds. React.act is no longer available in production builds. <a
href="https://redirect.github.com/facebook/react/pull/32200"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/32200/hovercard">#32200</a></li>
<li>Improved consistency across prod and dev to improve compatibility
with Google Closure Complier and bindings <a
href="https://redirect.github.com/facebook/react/pull/31808"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/31808/hovercard">#31808</a></li>
<li>Improve passive effect scheduling for consistent task yielding. <a
href="https://redirect.github.com/facebook/react/pull/31785"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/31785/hovercard">#31785</a></li>
<li>Fixed asserts in React Native when
passChildrenWhenCloningPersistedNodes is enabled for OffscreenComponent
rendering. <a
href="https://redirect.github.com/facebook/react/pull/32528"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/32528/hovercard">#32528</a></li>
<li>Fixed component name resolution for Portal <a
href="https://redirect.github.com/facebook/react/pull/32640"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/32640/hovercard">#32640</a></li>
<li>Added support for beforetoggle and toggle events on the dialog
element. <a class="issue-link js-issue-link" data-error-text="Failed to
load title" data-id="2882132160" data-permission-text="Title is private"
data-url="https://github.com/facebook/react/issues/32479"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/32479/hovercard"
href="https://redirect.github.com/facebook/react/pull/32479">#32479</a>
<a href="https://redirect.github.com/facebook/react/pull/32479"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/32479/hovercard">#32479</a></li>
</ul>
<h3>React DOM</h3>
<ul>
<li>Fixed double warning when the <code>href</code> attribute is an
empty string <a
href="https://redirect.github.com/facebook/react/pull/31783"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/31783/hovercard">#31783</a></li>
<li>Fixed an edge case where <code>getHoistableRoot()</code> didn’t work
properly when the container was a Document <a
href="https://redirect.github.com/facebook/react/pull/32321"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/32321/hovercard">#32321</a></li>
<li>Removed support for using HTML comments (e.g. <code><!--
--></code>) as a DOM container. <a
href="https://redirect.github.com/facebook/react/pull/32250"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/32250/hovercard">#32250</a></li>
<li>Added support for <code><script></code> and
<code><template></code> tags to be nested within
<code><select></code> tags. <a
href="https://redirect.github.com/facebook/react/pull/31837"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/31837/hovercard">#31837</a></li>
<li>Fixed responsive images to be preloaded as HTML instead of headers
<a href="https://redirect.github.com/facebook/react/pull/32445"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/32445/hovercard">#32445</a></li>
</ul>
<h3>use-sync-external-store</h3>
<ul>
<li>Added <code>exports</code> field to <code>package.json</code> for
<code>use-sync-external-store</code> to support various entrypoints. <a
href="https://redirect.github.com/facebook/react/pull/25231"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/25231/hovercard">#25231</a></li>
</ul>
<h3>React Server Components</h3>
<ul>
<li>Added <code>unstable_prerender</code>, a new experimental API for
prerendering React Server Components on the server <a
href="https://redirect.github.com/facebook/react/pull/31724"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/31724/hovercard">#31724</a></li>
<li>Fixed an issue where streams would hang when receiving new chunks
after a global error <a
href="https://redirect.github.com/facebook/react/pull/31840"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/31840/hovercard">#31840</a>, <a
href="https://redirect.github.com/facebook/react/pull/31851"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/31851/hovercard">#31851</a></li>
<li>Fixed an issue where pending chunks were counted twice. <a
href="https://redirect.github.com/facebook/react/pull/31833"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/31833/hovercard">#31833</a></li>
<li>Added support for streaming in edge environments <a
href="https://redirect.github.com/facebook/react/pull/31852"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/31852/hovercard">#31852</a></li>
<li>Added support for sending custom error names from a server so that
they are available in the client for console replaying. <a
href="https://redirect.github.com/facebook/react/pull/32116"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/32116/hovercard">#32116</a></li>
<li>Updated the server component wire format to remove IDs for hints and
console.log because they have no return value <a
href="https://redirect.github.com/facebook/react/pull/31671"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/31671/hovercard">#31671</a></li>
<li>Exposed <code>registerServerReference</code> in client builds to
handle server references in different environments. <a
href="https://redirect.github.com/facebook/react/pull/32534"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/32534/hovercard">#32534</a></li>
<li>Added react-server-dom-parcel package which integrates Server
Components with the <a href="https://parceljs.org/"
rel="nofollow">Parcel bundler</a> <a
href="https://redirect.github.com/facebook/react/pull/31725"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/31725/hovercard">#31725</a>, <a
href="https://redirect.github.com/facebook/react/pull/32132"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/32132/hovercard">#32132</a>, <a
href="https://redirect.github.com/facebook/react/pull/31799"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/31799/hovercard">#31799</a>, <a
href="https://redirect.github.com/facebook/react/pull/32294"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/32294/hovercard">#32294</a>, <a
href="https://redirect.github.com/facebook/react/pull/31741"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/31741/hovercard">#31741</a></li>
</ul>
</li>
<li>
<b>19.1.0-canary-ff628334-20250205</b> - 2025-02-06
</li>
<li>
<b>19.1.0-canary-fcb4e0f1-20250219</b> - 2025-02-20
</li>
<li>
<b>19.1.0-canary-fc8a898d-20241226</b> - 2024-12-27
</li>
<li>
<b>19.1.0-canary-fbcda19a-20250317</b> - 2025-03-17
</li>
<li>
<b>19.1.0-canary-f9d78089-20250306</b> - 2025-03-07
</li>
<li>
<b>19.1.0-canary-f83903bf-20250212</b> - 2025-02-12
</li>
<li>
<b>19.1.0-canary-f457d0b4-20250313</b> - 2025-03-13
</li>
<li>
<b>19.1.0-canary-f0edf41e-20250115</b> - 2025-01-14
</li>
<li>
<b>19.1.0-canary-ef979d47-20241218</b> - 2024-12-18
</li>
<li>
<b>19.1.0-canary-ef4bc8b4-20250328</b> - 2025-03-28
</li>
<li>
<b>19.1.0-canary-ebc22ef7-20250225</b> - 2025-02-26
</li>
<li>
<b>19.1.0-canary-e670e72f-20250214</b> - 2025-02-14
</li>
<li>
<b>19.1.0-canary-e1e74071-20250321</b> - 2025-03-21
</li>
<li>
<b>19.1.0-canary-e06c72fc-20241215</b> - 2024-12-16
</li>
<li>
<b>19.1.0-canary-e03ac20f-20250305</b> - 2025-03-05
</li>
<li>
<b>19.1.0-canary-de82912e-20241220</b> - 2024-12-20
</li>
<li>
<b>19.1.0-canary-de1eaa26-20250124</b> - 2025-01-24
</li>
<li>
<b>19.1.0-canary-db7dfe05-20250319</b> - 2025-03-19
</li>
<li>
<b>19.1.0-canary-d85cf3e5-20250205</b> - 2025-02-05
</li>
<li>
<b>19.1.0-canary-d55cc79b-20250228</b> - 2025-02-28
</li>
<li>
<b>19.1.0-canary-d46b04a2-20250117</b> - 2025-01-17
</li>
<li>
<b>19.1.0-canary-d4287258-20241217</b> - 2024-12-17
</li>
<li>
<b>19.1.0-canary-d331ba04-20250307</b> - 2025-03-10
</li>
<li>
<b>19.1.0-canary-cd90a4d8-20250210</b> - 2025-02-11
</li>
<li>
<b>19.1.0-canary-cbbe8666-20250213</b> - 2025-02-13
</li>
<li>
<b>19.1.0-canary-cabd8a0e-20250113</b> - 2025-01-13
</li>
<li>
<b>19.1.0-canary-c69a5fc5-20250318</b> - 2025-03-18
</li>
<li>
<b>19.1.0-canary-c492f975-20250128</b> - 2025-01-29
</li>
<li>
<b>19.1.0-canary-c01b8058-20241229</b> - 2024-12-30
</li>
<li>
<b>19.1.0-canary-bb9a24d9-20250130</b> - 2025-01-30
</li>
<li>
<b>19.1.0-canary-b3a95caf-20250113</b> - 2025-01-14
</li>
<li>
<b>19.1.0-canary-b158439a-20250115</b> - 2025-01-15
</li>
<li>
<b>19.1.0-canary-ae9017ce-20250122</b> - 2025-01-23
</li>
<li>
<b>19.1.0-canary-a84862db-20250218</b> - 2025-02-19
</li>
<li>
<b>19.1.0-canary-a4f9bd58-20250319</b> - 2025-03-20
</li>
<li>
<b>19.1.0-canary-a4b2d0d5-20250203</b> - 2025-02-03
</li>
<li>
<b>19.1.0-canary-9ff42a87-20250130</b> - 2025-01-31
</li>
<li>
<b>19.1.0-canary-9eabb373-20250124</b> - 2025-01-27
</li>
<li>
<b>19.1.0-canary-9b62ee71-20250122</b> - 2025-01-22
</li>
<li>
<b>19.1.0-canary-97d79495-20241223</b> - 2024-12-24
</li>
<li>
<b>19.1.0-canary-9463d51e-20241219</b> - 2024-12-19
</li>
<li>
<b>19.1.0-canary-93b58361-20250209</b> - 2025-02-10
</li>
<li>
<b>19.1.0-canary-8a7b487e-20250218</b> - 2025-02-18
</li>
<li>
<b>19.1.0-canary-8759c5c8-20250207</b> - 2025-02-07
</li>
<li>
<b>19.1.0-canary-7eb8234f-20241218</b> - 2024-12-18
</li>
<li>
<b>19.1.0-canary-7b402084-20250107</b> - 2025-01-07
</li>
<li>
<b>19.1.0-canary-74ea0c73-20250109</b> - 2025-01-09
</li>
<li>
<b>19.1.0-canary-740a4f7a-20250325</b> - 2025-03-25
</li>
<li>
<b>19.1.0-canary-7130d0c6-20241212</b> - 2024-12-12
</li>
<li>
<b>19.1.0-canary-6aa8254b-20250312</b> - 2025-03-12
</li>
<li>
<b>19.1.0-canary-694d3e1a-20241231</b> - 2025-01-01
</li>
<li>
<b>19.1.0-canary-6907aa2a-20241220</b> - 2024-12-23
</li>
<li>
<b>19.1.0-canary-662957cc-20250221</b> - 2025-02-21
</li>
<li>
<b>19.1.0-canary-62208bee-20250102</b> - 2025-01-02
</li>
<li>
<b>19.1.0-canary-5b51a2b9-20250116</b> - 2025-01-16
</li>
<li>
<b>19.1.0-canary-540efebc-20250112</b> - 2025-01-12
</li>
<li>
<b>19.1.0-canary-5398b711-20250314</b> - 2025-03-14
</li>
<li>
<b>19.1.0-canary-518d06d2-20241219</b> - 2024-12-19
</li>
<li>
<b>19.1.0-canary-4dff0e62-20241213</b> - 2024-12-13
</li>
<li>
<b>19.1.0-canary-4632e36a-20250216</b> - 2025-02-17
</li>
<li>
<b>19.1.0-canary-443b7ff2-20250303</b> - 2025-03-04
</li>
<li>
<b>19.1.0-canary-4280563b-20250326</b> - 2025-03-27
</li>
<li>
<b>19.1.0-canary-42687267-20250108</b> - 2025-01-08
</li>
<li>
<b>19.1.0-canary-3ce77d55-20250106</b> - 2025-01-06
</li>
<li>
<b>19.1.0-canary-3b009b4c-20250102</b> - 2025-01-03
</li>
<li>
<b>19.1.0-canary-37906d4d-20250127</b> - 2025-01-28
</li>
<li>
<b>19.1.0-canary-32b0cad8-20250213</b> - 2025-02-13
</li>
<li>
<b>19.1.0-canary-313332d1-20250326</b> - 2025-03-26
</li>
<li>
<b>19.1.0-canary-2980f277-20250301</b> - 2025-03-03
</li>
<li>
<b>19.1.0-canary-25677265-20250224</b> - 2025-02-24
</li>
<li>
<b>19.1.0-canary-22e39ea7-20250225</b> - 2025-02-25
</li>
<li>
<b>19.1.0-canary-18eaf51b-20250118</b> - 2025-01-20
</li>
<li>
<b>19.1.0-canary-130095f7-20241212</b> - 2024-12-12
</li>
<li>
<b>19.1.0-canary-0ca3deeb-20250311</b> - 2025-03-11
</li>
<li>
<b>19.1.0-canary-0a82580b-20250203</b> - 2025-02-04
</li>
<li>
<b>19.1.0-canary-056073de-20250109</b> - 2025-01-10
</li>
<li>
<b>19.1.0-canary-029e8bd6-20250306</b> - 2025-03-06
</li>
<li>
<b>19.0.0</b> - <a
href="https://redirect.github.com/facebook/react/releases/tag/v19.0.0">2024-12-05</a></br><p>Below
is a list of all new features, APIs, deprecations, and breaking changes.
Read <a href="https://react.dev/blog/2024/04/25/react-19"
rel="nofollow">React 19 release post</a> and <a
href="https://react.dev/blog/2024/04/25/react-19-upgrade-guide"
rel="nofollow">React 19 upgrade guide</a> for more information.</p>
<blockquote>
<p>Note: To help make the upgrade to React 19 easier, we’ve published a
react@18.3 release that is identical to 18.2 but adds warnings for
deprecated APIs and other changes that are needed for React 19. We
recommend upgrading to React 18.3.1 first to help identify any issues
before upgrading to React 19.</p>
</blockquote>
<h2>New Features</h2>
<h3>React</h3>
<ul>
<li>Actions: <code>startTransition</code> can now accept async
functions. Functions passed to <code>startTransition</code> are called
“Actions”. A given Transition can include one or more Actions which
update state in the background and update the UI with one commit. In
addition to updating state, Actions can now perform side effects
including async requests, and the Action will wait for the work to
finish before finishing the Transition. This feature allows Transitions
to include side effects like <code>fetch()</code> in the pending state,
and provides support for error handling, and optimistic updates.</li>
<li><code>useActionState</code>: is a new hook to order Actions inside
of a Transition with access to the state of the action, and the pending
state. It accepts a reducer that can call Actions, and the initial state
used for first render. It also accepts an optional string that is used
if the action is passed to a form <code>action</code> prop to support
progressive enhancement in forms.</li>
<li><code>useOptimistic</code>: is a new hook to update state while a
Transition is in progress. It returns the state, and a set function that
can be called inside a transition to “optimistically” update the state
to expected final value immediately while the Transition completes in
the background. When the transition finishes, the state is updated to
the new value.</li>
<li><code>use</code>: is a new API that allows reading resources in
render. In React 19, <code>use</code> accepts a promise or Context. If
provided a promise, <code>use</code> will suspend until a value is
resolved. <code>use</code> can only be used in render but can be called
conditionally.</li>
<li><code>ref</code> as a prop: Refs can now be used as props, removing
the need for <code>forwardRef</code>.</li>
<li><strong>Suspense sibling pre-warming</strong>: When a component
suspends, React will immediately commit the fallback of the nearest
Suspense boundary, without waiting for the entire sibling tree to
render. After the fallback commits, React will schedule another render
for the suspended siblings to “pre-warm” lazy requests.</li>
</ul>
<h3>React DOM Client</h3>
<ul>
<li><code><form> action</code> prop: Form Actions allow you to
manage forms automatically and integrate with
<code>useFormStatus</code>. When a <code><form> action</code>
succeeds, React will automatically reset the form for uncontrolled
components. The form can be reset manually with the new
<code>requestFormReset</code> API.</li>
<li><code><button> and <input> formAction</code> prop:
Actions can be passed to the <code>formAction</code> prop to configure
form submission behavior. This allows using different Actions depending
on the input.</li>
<li><code>useFormStatus</code>: is a new hook that provides the status
of the parent <code><form> action</code>, as if the form was a
Context provider. The hook returns the values: <code>pending</code>,
<code>data</code>, <code>method</code>, and <code>action</code>.</li>
<li>Support for Document Metadata: We’ve added support for rendering
document metadata tags in components natively. React will automatically
hoist them into the <code><head></code> section of the
document.</li>
<li>Support for Stylesheets: React 19 will ensure stylesheets are
inserted into the <code><head></code> on the client before
revealing the content of a Suspense boundary that depends on that
stylesheet.</li>
<li>Support for async scripts: Async scripts can be rendered anywhere in
the component tree and React will handle ordering and
deduplication.</li>
<li>Support for preloading resources: React 19 ships with
<code>preinit</code>, <code>preload</code>, <code>prefetchDNS</code>,
and <code>preconnect</code> APIs to optimize initial page loads by
moving discovery of additional resources like fonts out of stylesheet
loading. They can also be used to prefetch resources used by an
anticipated navigation.</li>
</ul>
<h3>React DOM Server</h3>
<ul>
<li>Added <code>prerender</code> and <code>prerenderToNodeStream</code>
APIs for static site generation. They are designed to work with
streaming environments like Node.js Streams and Web Streams. Unlike
<code>renderToString</code>, they wait for data to load for HTML
generation.</li>
</ul>
<h3>React Server Components</h3>
<ul>
<li>RSC features such as directives, server components, and server
functions are now stable. This means libraries that ship with Server
Components can now target React 19 as a peer dependency with a
react-server export condition for use in frameworks that support the
Full-stack React Architecture. The underlying APIs used to implement a
React Server Components bundler or framework do not follow semver and
may break between minors in React 19.x. See <a
href="https://19.react.dev/reference/rsc/server-components"
rel="nofollow">docs</a> for how to support React Server Components.</li>
</ul>
<h2>Deprecations</h2>
<ul>
<li>Deprecated: <code>element.ref</code> access: React 19 supports ref
as a prop, so we’re deprecating <code>element.ref</code> in favor of
<code>element.props.ref</code>. Accessing will result in a warning.</li>
<li><code>react-test-renderer</code>: In React 19, react-test-renderer
logs a deprecation warning and has switched to concurrent rendering for
web usage. We recommend migrating your tests to @
testinglibrary.com/docs/react-testing-library/intro/) or @
testingesting-library.com/docs/react-native-testing-library/intro)</li>
</ul>
<h2>Breaking Changes</h2>
<p>React 19 brings in a number of breaking changes, including the
removals of long-deprecated APIs. We recommend first upgrading to
<code>18.3.1</code>, where we've added additional deprecation warnings.
Check out the <a
href="https://19.react.dev/blog/2024/04/25/react-19-upgrade-guide"
rel="nofollow">upgrade guide</a> for more details and guidance on
codemodding.</p>
<h3>React</h3>
<ul>
<li>New JSX Transform is now required: We introduced <a
href="https://legacy.reactjs.org/blog/2020/09/22/introducing-the-new-jsx-transform.html"
rel="nofollow">a new JSX transform</a> in 2020 to improve bundle size
and use JSX without importing React. In React 19, we’re adding
additional improvements like using ref as a prop and JSX speed
improvements that require the new transform.</li>
<li>Errors in render are not re-thrown: Errors that are not caught by an
Error Boundary are now reported to window.reportError. Errors that are
caught by an Error Boundary are reported to console.error. We’ve
introduced <code>onUncaughtError</code> and <code>onCaughtError</code>
methods to <code>createRoot</code> and <code>hydrateRoot</code> to
customize this error handling.</li>
<li>Removed: <code>propTypes</code>: Using <code>propTypes</code> will
now be silently ignored. If required, we recommend migrating to
TypeScript or another type-checking solution.</li>
<li>Removed: <code>defaultProps</code> for functions: ES6 default
parameters can be used in place. Class components continue to support
<code>defaultProps</code> since there is no ES6 alternative.</li>
<li>Removed: <code>contextTypes</code> and <code>getChildContext</code>:
Legacy Context for class components has been removed in favor of the
<code>contextType</code> API.</li>
<li>Removed: string refs: Any usage of string refs need to be migrated
to ref callbacks.</li>
<li>Removed: Module pattern factories: A rarely used pattern that can be
migrated to regular functions.</li>
<li>Removed: <code>React.createFactory</code>: Now that JSX is broadly
supported, all <code>createFactory</code> usage can be migrated to JSX
components.</li>
<li>Removed: <code>react-test-renderer/shallow</code>: This has been a
re-export of <a
href="https://redirect.github.com/enzymejs/react-shallow-renderer">react-shallow-renderer</a>
since React 18. If needed, you can continue to use the third-party
package directly. We recommend using @
testinglibrary.com/docs/react-testing-library/intro/) or @
testingesting-library.com/docs/react-native-testing-library/intro)
instead.</li>
</ul>
<h3>React DOM</h3>
<ul>
<li>Removed: <code>react-dom/test-utils</code>: We’ve moved
<code>act</code> from <code>react-dom/test-utils</code> to react. All
other utilities have been removed.</li>
<li>Removed: <code>ReactDOM</code>.<code>render</code>,
<code>ReactDOM</code>.<code>hydrate</code>: These have been removed in
favor of the concurrent equivalents:
<code>ReactDOM</code>.<code>createRoot</code> and
<code>ReactDOM.hydrateRoot</code>.</li>
<li>Removed: <code>unmountComponentAtNode</code>: Removed in favor of
<code>root.unmount()</code>.</li>
<li>Removed: <code>ReactDOM</code>.<code>findDOMNode</code>: You can
replace <code>ReactDOM</code>.<code>findDOMNode</code> with DOM
Refs.</li>
</ul>
<h2>Notable Changes</h2>
<h3>React</h3>
<ul>
<li><code><Context></code> as a provider: You can now render
<code><Context></code> as a provider instead of
<code><Context.Provider></code>.</li>
<li>Cleanup functions for refs: When the component unmounts, React will
call the cleanup function returned from the ref callback.</li>
<li><code>useDeferredValue</code> initial value argument: When provided,
<code>useDeferredValue</code> will return the initial value for the
initial render of a component, then schedule a re-render in the
background with the <code>deferredValue</code> returned.</li>
<li>Support for Custom Elements: React 19 now passes all tests on <a
href="https://custom-elements-everywhere.com/" rel="nofollow">Custom
Elements Everywhere</a>.</li>
<li>StrictMode changes: <code>useMemo</code> and
<code>useCallback</code> will now reuse the memoized results from the
first render, during the second render. Additionally, StrictMode will
now double-invoke ref callback functions on initial mount.</li>
<li>UMD builds removed: To load React 19 with a script tag, we recommend
using an ESM-based CDN such as <a href="http://esm.sh"
rel="nofollow">esm.sh</a>.</li>
</ul>
<h3>React DOM</h3>
<ul>
<li>Diffs for hydration errors: In the case of a mismatch, React 19 logs
a single error with a diff of the mismatched content.</li>
<li>Compatibility with third-party scripts and extensions: React will
now force a client re-render to fix up any mismatched content caused by
elements inserted by third-party JS.</li>
</ul>
<h2>TypeScript Changes</h2>
<p>The most common changes can be codemodded with <code>npx
types-react-codemod@latest preset-19
./path-to-your-react-ts-files</code>.</p>
<ul>
<li>Removed deprecated TypeScript types:
<ul>
<li><code>ReactChild</code> (replacement: <code>React.ReactElement |
number | string)</code></li>
<li><code>ReactFragment</code> (replacement:
<code>Iterable<React.ReactNode></code>)</li>
<li><code>ReactNodeArray</code> (replacement:
<code>ReadonlyArray<React.ReactNode></code>)</li>
<li><code>ReactText</code> (replacement: <code>number |
string</code>)</li>
<li><code>VoidFunctionComponent</code> (replacement:
<code>FunctionComponent</code>)</li>
<li><code>VFC</code> (replacement: <code>FC</code>)</li>
<li>Moved to <code>prop-types</code>: <code>Requireable</code>,
<code>ValidationMap</code>, <code>Validator</code>,
<code>WeakValidationMap</code></li>
<li>Moved to <code>create-react-class</code>:
<code>ClassicComponentClass</code>, <code>ClassicComponent</code>,
<code>ClassicElement</code>, <code>ComponentSpec</code>,
<code>Mixin</code>, <code>ReactChildren</code>, <code>ReactHTML</code>,
<code>ReactSVG</code>, <code>SFCFactory</code></li>
</ul>
</li>
<li>Disallow implicit return in refs: refs can now accept cleanup
functions. When you return something else, we can’t tell if you
intentionally returned something not meant to clean up or returned the
wrong value. Implicit returns of anything but functions will now
error.</li>
<li>Require initial argument to <code>useRef</code>: The initial
argument is now required to match <code>useState</code>,
<code>createContext</code> etc</li>
<li>Refs are mutable by default: Ref objects returned from
<code>useRef()</code> are now always mutable instead of sometimes being
immutable. This feature was too confusing for users and conflicted with
legit cases where refs were managed by React and manually written
to.</li>
<li>Strict <code>ReactElement</code> typing: The props of React elements
now default to <code>unknown</code> instead of <code>any</code> if the
element is typed as <code>ReactElement</code></li>
<li>JSX namespace in TypeScript: The global <code>JSX</code> namespace
is removed to improve interoperability with other libraries using JSX.
Instead, the JSX namespace is available from the React package:
<code>import { JSX } from 'react'</code></li>
<li>Better <code>useReducer</code> typings: Most <code>useReducer</code>
usage should not require explicit type arguments.<br>
For example,
<div class="highlight highlight-source-diff notranslate
position-relative overflow-auto"
data-snippet-clipboard-copy-content="-useReducer<React.Reducer<State,
Action>>(reducer)
+useReducer(reducer) "><pre><span class="pl-md"><span
class="pl-md">-</span>useReducer<React.Reducer<State,
Action>>(reducer) </span>
<span class="pl-mi1"><span class="pl-mi1">+</span>useReducer(reducer)
</span></pre></div>
or
<div class="highlight highlight-source-diff notranslate
position-relative overflow-auto"
data-snippet-clipboard-copy-content="-useReducer<React.Reducer<State,
Action>>(reducer)
+useReducer<State, [Action]>(reducer)"><pre><span
class="pl-md"><span
class="pl-md">-</span>useReducer<React.Reducer<State,
Action>>(reducer) </span>
<span class="pl-mi1"><span class="pl-mi1">+</span>useReducer<State,
[Action]>(reducer)</span></pre></div>
</li>
</ul>
<h2>All Changes</h2>
<h3>React</h3>
<ul>
<li>Add support for async Actions (<a
href="https://redirect.github.com/facebook/react/pull/26621"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/26621/hovercard">#26621</a>, <a
href="https://redirect.github.com/facebook/react/pull/26726"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/26726/hovercard">#26726</a>, <a
href="https://redirect.github.com/facebook/react/pull/28078"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/28078/hovercard">#28078</a>, <a
href="https://redirect.github.com/facebook/react/pull/28097"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/28097/hovercard">#28097</a>, <a
href="https://redirect.github.com/facebook/react/pull/29226"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/29226/hovercard">#29226</a>, <a
href="https://redirect.github.com/facebook/react/pull/29618"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/29618/hovercard">#29618</a>, <a
href="https://redirect.github.com/facebook/react/pull/29670"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/29670/hovercard">#29670</a>, <a
href="https://redirect.github.com/facebook/react/pull/26716"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/26716/hovercard">#26716</a> by
<a class="user-mention notranslate" data-hovercard-type="user"
data-hovercard-url="/users/acdlite/hovercard"
data-octo-click="hovercard-link-click"
data-octo-dimensions="link_type:self"
href="https://redirect.github.com/acdlite">@ acdlite</a> and <a
class="user-mention notranslate" data-hovercard-type="user"
data-hovercard-url="/users/sebmarkbage/hovercard"
data-octo-click="hovercard-link-click"
data-octo-dimensions="link_type:self"
href="https://redirect.github.com/sebmarkbage">@ sebmarkbage</a>)</li>
<li>Add <code>useActionState()</code> hook to update state based on the
result of a Form Action (<a
href="https://redirect.github.com/facebook/react/pull/27270"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/27270/hovercard">#27270</a>, <a
href="https://redirect.github.com/facebook/react/pull/27278"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/27278/hovercard">#27278</a>, <a
href="https://redirect.github.com/facebook/react/pull/27309"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/27309/hovercard">#27309</a>, <a
href="https://redirect.github.com/facebook/react/pull/27302"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/27302/hovercard">#27302</a>, <a
href="https://redirect.github.com/facebook/react/pull/27307"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/27307/hovercard">#27307</a>, <a
href="https://redirect.github.com/facebook/react/pull/27366"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/27366/hovercard">#27366</a>, <a
href="https://redirect.github.com/facebook/react/pull/27370"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/27370/hovercard">#27370</a>, <a
href="https://redirect.github.com/facebook/react/pull/27321"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/27321/hovercard">#27321</a>, <a
href="https://redirect.github.com/facebook/react/pull/27374"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/27374/hovercard">#27374</a>, <a
href="https://redirect.github.com/facebook/react/pull/27372"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/27372/hovercard">#27372</a>, <a
href="https://redirect.github.com/facebook/react/pull/27397"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/27397/hovercard">#27397</a>, <a
href="https://redirect.github.com/facebook/react/pull/27399"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/27399/hovercard">#27399</a>, <a
href="https://redirect.github.com/facebook/react/pull/27460"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/27460/hovercard">#27460</a>, <a
href="https://redirect.github.com/facebook/react/pull/28557"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/28557/hovercard">#28557</a>, <a
href="https://redirect.github.com/facebook/react/pull/27570"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/27570/hovercard">#27570</a>, <a
href="https://redirect.github.com/facebook/react/pull/27571"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/27571/hovercard">#27571</a>, <a
href="https://redirect.github.com/facebook/react/pull/28631"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/28631/hovercard">#28631</a>, <a
href="https://redirect.github.com/facebook/react/pull/28788"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/28788/hovercard">#28788</a>, <a
href="https://redirect.github.com/facebook/react/pull/29694"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/29694/hovercard">#29694</a>, <a
href="https://redirect.github.com/facebook/react/pull/29695"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/29695/hovercard">#29695</a>, <a
href="https://redirect.github.com/facebook/react/pull/29694"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/29694/hovercard">#29694</a>, <a
href="https://redirect.github.com/facebook/react/pull/29665"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/29665/hovercard">#29665</a>, <a
href="https://redirect.github.com/facebook/react/pull/28232"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/28232/hovercard">#28232</a>, <a
href="https://redirect.github.com/facebook/react/pull/28319"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/28319/hovercard">#28319</a> by
<a class="user-mention notranslate" data-hovercard-type="user"
data-hovercard-url="/users/acdlite/hovercard"
data-octo-click="hovercard-link-click"
data-octo-dimensions="link_type:self"
href="https://redirect.github.com/acdlite">@ acdlite</a>, <a
class="user-mention notranslate" data-hovercard-type="user"
data-hovercard-url="/users/eps1lon/hovercard"
data-octo-click="hovercard-link-click"
data-octo-dimensions="link_type:self"
href="https://redirect.github.com/eps1lon">@ eps1lon</a>, and <a
class="user-mention notranslate" data-hovercard-type="user"
data-hovercard-url="/users/rickhanlonii/hovercard"
data-octo-click="hovercard-link-click"
data-octo-dimensions="link_type:self"
href="https://redirect.github.com/rickhanlonii">@ rickhanlonii</a>)</li>
<li>Add <code>use()</code> API to read resources in render (<a
href="https://redirect.github.com/facebook/react/pull/25084"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/25084/hovercard">#25084</a>, <a
href="https://redirect.github.com/facebook/react/pull/25202"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/25202/hovercard">#25202</a>, <a
href="https://redirect.github.com/facebook/react/pull/25207"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/25207/hovercard">#25207</a>, <a
href="https://redirect.github.com/facebook/react/pull/25214"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/25214/hovercard">#25214</a>, <a
href="https://redirect.github.com/facebook/react/pull/25226"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/25226/hovercard">#25226</a>, <a
href="https://redirect.github.com/facebook/react/pull/25247"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/25247/hovercard">#25247</a>, <a
href="https://redirect.github.com/facebook/react/pull/25539"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/25539/hovercard">#25539</a>, <a
href="https://redirect.github.com/facebook/react/pull/25538"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/25538/hovercard">#25538</a>, <a
href="https://redirect.github.com/facebook/react/pull/25537"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/25537/hovercard">#25537</a>, <a
href="https://redirect.github.com/facebook/react/pull/25543"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/25543/hovercard">#25543</a>, <a
href="https://redirect.github.com/facebook/react/pull/25561"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/25561/hovercard">#25561</a>, <a
href="https://redirect.github.com/facebook/react/pull/25620"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/25620/hovercard">#25620</a>, <a
href="https://redirect.github.com/facebook/react/pull/25615"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/25615/hovercard">#25615</a>, <a
href="https://redirect.github.com/facebook/react/pull/25922"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/25922/hovercard">#25922</a>, <a
href="https://redirect.github.com/facebook/react/pull/25641"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/25641/hovercard">#25641</a>, <a
href="https://redirect.github.com/facebook/react/pull/25634"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/25634/hovercard">#25634</a>, <a
href="https://redirect.github.com/facebook/react/pull/26232"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/26232/hovercard">#26232</a>, <a
href="https://redirect.github.com/facebook/react/pull/26535"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/26535/hovercard">#26536</a>, <a
href="https://redirect.github.com/facebook/react/pull/26739"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/26739/hovercard">#26739</a>, <a
href="https://redirect.github.com/facebook/react/pull/28233"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/28233/hovercard">#28233</a> by
<a class="user-mention notranslate" data-hovercard-type="user"
data-hovercard-url="/users/acdlite/hovercard"
data-octo-click="hovercard-link-click"
data-octo-dimensions="link_type:self"
href="https://redirect.github.com/acdlite">@ acdlite</a>, <a
class="user-mention notranslate" data-hovercard-type="user"
data-hovercard-url="/users/mofeiZ/hovercard"
data-octo-click="hovercard-link-click"
data-octo-dimensions="link_type:self"
href="https://redirect.github.com/mofeiZ">@ mofeiZ</a>, <a
class="user-mention notranslate" data-hovercard-type="user"
data-hovercard-url="/users/sebmarkbage/hovercard"
data-octo-click="hovercard-link-click"
data-octo-dimensions="link_type:self"
href="https://redirect.github.com/sebmarkbage">@ sebmarkbage</a>, <a
class="user-mention notranslate" data-hovercard-type="user"
data-hovercard-url="/users/sophiebits/hovercard"
data-octo-click="hovercard-link-click"
data-octo-dimensions="link_type:self"
href="https://redirect.github.com/sophiebits">@ sophiebits</a>, <a
class="user-mention notranslate" data-hovercard-type="user"
data-hovercard-url="/users/eps1lon/hovercard"
data-octo-click="hovercard-link-click"
data-octo-dimensions="link_type:self"
href="https://redirect.github.com/eps1lon">@ eps1lon</a>, and <a
class="user-mention notranslate" data-hovercard-type="user"
data-hovercard-url="/users/hansottowirtz/hovercard"
data-octo-click="hovercard-link-click"
data-octo-dimensions="link_type:self"
href="https://redirect.github.com/hansottowirtz">@
hansottowirtz</a>)</li>
<li>Add <code>useOptimistic()</code> hook to display mutated state
optimistically during an async mutation (<a
href="https://redirect.github.com/facebook/react/pull/26740"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/26740/hovercard">#26740</a>, <a
href="https://redirect.github.com/facebook/react/pull/26772"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/26772/hovercard">#26772</a>, <a
href="https://redirect.github.com/facebook/react/pull/27277"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/27277/hovercard">#27277</a>, <a
href="https://redirect.github.com/facebook/react/pull/27453"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/27453/hovercard">#27453</a>, <a
href="https://redirect.github.com/facebook/react/pull/27454"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/27454/hovercard">#27454</a>, <a
href="https://redirect.github.com/facebook/react/pull/27936"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/27936/hovercard">#27936</a> by
<a class="user-mention notranslate" data-hovercard-type="user"
data-hovercard-url="/users/acdlite/hovercard"
data-octo-click="hovercard-link-click"
data-octo-dimensions="link_type:self"
href="https://redirect.github.com/acdlite">@ acdlite</a>)</li>
<li>Added an <code>initialValue</code> argument to
<code>useDeferredValue()</code> hook (<a
href="https://redirect.github.com/facebook/react/pull/27500"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/27500/hovercard">#27500</a>, <a
href="https://redirect.github.com/facebook/react/pull/27509"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/27509/hovercard">#27509</a>, <a
href="https://redirect.github.com/facebook/react/pull/27512"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/27512/hovercard">#27512</a>, <a
href="https://redirect.github.com/facebook/react/pull/27888"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/27888/hovercard">#27888</a>, <a
href="https://redirect.github.com/facebook/react/pull/27550"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/27550/hovercard">#27550</a> by
<a class="user-mention notranslate" data-hovercard-type="user"
data-hovercard-url="/users/acdlite/hovercard"
data-octo-click="hovercard-link-click"
data-octo-dimensions="link_type:self"
href="https://redirect.github.com/acdlite">@ acdlite</a>)</li>
<li>Support refs as props, warn on <code>element.ref</code> access (<a
href="https://redirect.github.com/facebook/react/pull/28348"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/28348/hovercard">#28348</a>, <a
href="https://redirect.github.com/facebook/react/pull/28464"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/28464/hovercard">#28464</a>, <a
href="https://redirect.github.com/facebook/react/pull/28731"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/28731/hovercard">#28731</a> by
<a class="user-mention notranslate" data-hovercard-type="user"
data-hovercard-url="/users/acdlite/hovercard"
data-octo-click="hovercard-link-click"
data-octo-dimensions="link_type:self"
href="https://redirect.github.com/acdlite">@ acdlite</a>)</li>
<li>Support Custom Elements (<a
href="https://redirect.github.com/facebook/react/pull/22184"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/22184/hovercard">#22184</a>, <a
href="https://redirect.github.com/facebook/react/pull/26524"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/26524/hovercard">#26524</a>, <a
href="https://redirect.github.com/facebook/react/pull/26523"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/26523/hovercard">#26523</a>, <a
href="https://redirect.github.com/facebook/react/pull/27511"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/27511/hovercard">#27511</a>, <a
href="https://redirect.github.com/facebook/react/pull/24541"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/24541/hovercard">#24541</a> by
<a class="user-mention notranslate" data-hovercard-type="user"
data-hovercard-url="/users/josepharhar/hovercard"
data-octo-click="hovercard-link-click"
data-octo-dimensions="link_type:self"
href="https://redirect.github.com/josepharhar">@ josepharhar</a>, <a
class="user-mention notranslate" data-hovercard-type="user"
data-hovercard-url="/users/sebmarkbage/hovercard"
data-octo-click="hovercard-link-click"
data-octo-dimensions="link_type:self"
href="https://redirect.github.com/sebmarkbage">@ sebmarkbage</a>, <a
class="user-mention notranslate" data-hovercard-type="user"
data-hovercard-url="/users/gnoff/hovercard"
data-octo-click="hovercard-link-click"
data-octo-dimensions="link_type:self"
href="https://redirect.github.com/gnoff">@ gnoff</a> and <a
class="user-mention notranslate" data-hovercard-type="user"
data-hovercard-url="/users/eps1lon/hovercard"
data-octo-click="hovercard-link-click"
data-octo-dimensions="link_type:self"
href="https://redirect.github.com/eps1lon">@ eps1lon</a>)</li>
<li>Add ref cleanup function (<a
href="https://redirect.github.com/facebook/react/pull/25686"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/25686/hovercard">#25686</a>, <a
href="https://redirect.github.com/facebook/react/pull/28883"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/28883/hovercard">#28883</a>, <a
href="https://redirect.github.com/facebook/react/pull/28910"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/28910/hovercard">#28910</a> by
<a class="user-mention notranslate" data-hovercard-type="user"
data-hovercard-url="/users/sammy-SC/hovercard"
data-octo-click="hovercard-link-click"
data-octo-dimensions="link_type:self"
href="https://redirect.github.com/sammy-SC">@ sammy-SC</a>), <a
class="user-mention notranslate" data-hovercard-type="user"
data-hovercard-url="/users/jackpope/hovercard"
data-octo-click="hovercard-link-click"
data-octo-dimensions="link_type:self"
href="https://redirect.github.com/jackpope">@ jackpope</a>, and <a
class="user-mention notranslate" data-hovercard-type="user"
data-hovercard-url="/users/kassens/hovercard"
data-octo-click="hovercard-link-click"
data-octo-dimensions="link_type:self"
href="https://redirect.github.com/kassens">@ kassens</a>)</li>
<li>Sibling pre-rendering replaced by sibling pre-warming (<a
href="https://redirect.github.com/facebook/react/pull/26380"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/26380/hovercard">#26380</a>, <a
href="https://redirect.github.com/facebook/react/pull/26549"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/26549/hovercard">#26549</a>, <a
href="https://redirect.github.com/facebook/react/pull/30761"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/30761/hovercard">#30761</a>, <a
href="https://redirect.github.com/facebook/react/pull/30800"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/30800/hovercard">#30800</a>, <a
href="https://redirect.github.com/facebook/react/pull/30762"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/30762/hovercard">#30762</a>, <a
href="https://redirect.github.com/facebook/react/pull/30879"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/30879/hovercard">#30879</a>, <a
href="https://redirect.github.com/facebook/react/pull/30934"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/30934/hovercard">#30934</a>, <a
href="https://redirect.github.com/facebook/react/pull/30952"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/30952/hovercard">#30952</a>, <a
href="https://redirect.github.com/facebook/react/pull/31056"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/31056/hovercard">#31056</a>, <a
href="https://redirect.github.com/facebook/react/pull/31452"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/31452/hovercard">#31452</a> by
<a class="user-mention notranslate" data-hovercard-type="user"
data-hovercard-url="/users/sammy-SC/hovercard"
data-octo-click="hovercard-link-click"
data-octo-dimensions="link_type:self"
href="https://redirect.github.com/sammy-SC">@ sammy-SC</a>), <a
class="user-mention notranslate" data-hovercard-type="user"
data-hovercard-url="/users/acdlite/hovercard"
data-octo-click="hovercard-link-click"
data-octo-dimensions="link_type:self"
href="https://redirect.github.com/acdlite">@ acdlite</a>, <a
class="user-mention notranslate" data-hovercard-type="user"
data-hovercard-url="/users/gnoff/hovercard"
data-octo-click="hovercard-link-click"
data-octo-dimensions="link_type:self"
href="https://redirect.github.com/gnoff">@ gnoff</a>, <a
class="user-mention notranslate" data-hovercard-type="user"
data-hovercard-url="/users/jackpope/hovercard"
data-octo-click="hovercard-link-click"
data-octo-dimensions="link_type:self"
href="https://redirect.github.com/jackpope">@ jackpope</a>, <a
class="user-mention notranslate" data-hovercard-type="user"
data-hovercard-url="/users/rickhanlonii/hovercard"
data-octo-click="hovercard-link-click"
data-octo-dimensions="link_type:self"
href="https://redirect.github.com/rickhanlonii">@ rickhanlonii</a>)</li>
<li>Don’t rethrow errors at the root (<a
href="https://redirect.github.com/facebook/react/pull/28627"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/28627/hovercard">#28627</a>, <a
href="https://redirect.github.com/facebook/react/pull/28641"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/28641/hovercard">#28641</a> by
<a class="user-mention notranslate" data-hovercard-type="user"
data-hovercard-url="/users/sebmarkbage/hovercard"
data-octo-click="hovercard-link-click"
data-octo-dimensions="link_type:self"
href="https://redirect.github.com/sebmarkbage">@ sebmarkbage</a>)</li>
<li>Batch sync discrete, continuous, and default lanes (<a
href="https://redirect.github.com/facebook/react/pull/25700"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/25700/hovercard">#25700</a> by
<a class="user-mention notranslate" data-hovercard-type="user"
data-hovercard-url="/users/tyao1/hovercard"
data-octo-click="hovercard-link-click"
data-octo-dimensions="link_type:self"
href="https://redirect.github.com/tyao1">@ tyao1</a>)</li>
<li>Switch <code><Context></code> to mean
<code><Context.Provider></code> (<a
href="https://redirect.github.com/facebook/react/pull/28226"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/28226/hovercard">#28226</a> by
<a class="user-mention notranslate" data-hovercard-type="user"
data-hovercard-url="/users/gaearon/hovercard"
data-octo-click="hovercard-link-click"
data-octo-dimensions="link_type:self"
href="https://redirect.github.com/gaearon">@ gaearon</a>)</li>
<li>Changes to <em>StrictMode</em>
<ul>
<li>Handle <code>info</code>, <code>group</code>, and
<code>groupCollapsed</code> in <em>StrictMode</em> logging (<a
href="https://redirect.github.com/facebook/react/pull/25172"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/25172/hovercard">#25172</a> by
<a class="user-mention notranslate" data-hovercard-type="user"
data-hovercard-url="/users/timneutkens/hovercard"
data-octo-click="hovercard-link-click"
data-octo-dimensions="link_type:self"
href="https://redirect.github.com/timneutkens">@ timneutkens</a>)</li>
<li>Refs are now attached/detached/attached in <em>StrictMode</em> (<a
href="https://redirect.github.com/facebook/react/pull/25049"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/25049/hovercard">#25049</a> by
<a class="user-mention notranslate" data-hovercard-type="user"
data-hovercard-url="/users/sammy-SC/hovercard"
data-octo-click="hovercard-link-click"
data-octo-dimensions="link_type:self"
href="https://redirect.github.com/sammy-SC">@ sammy-SC</a>)</li>
<li>Fix <code>useSyncExternalStore()</code> hydration in
<em>StrictMode</em> (<a
href="https://redirect.github.com/facebook/react/pull/26791"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/26791/hovercard">#26791</a> by
<a class="user-mention notranslate" data-hovercard-type="user"
data-hovercard-url="/users/sophiebits/hovercard"
data-octo-click="hovercard-link-click"
data-octo-dimensions="link_type:self"
href="https://redirect.github.com/sophiebits">@ sophiebits</a>)</li>
<li>Always trigger <code>componentWillUnmount()</code> in
<em>StrictMode</em> (<a
href="https://redirect.github.com/facebook/react/pull/26842"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/26842/hovercard">#26842</a> by
<a class="user-mention notranslate" data-hovercard-type="user"
data-hovercard-url="/users/tyao1/hovercard"
data-octo-click="hovercard-link-click"
data-octo-dimensions="link_type:self"
href="https://redirect.github.com/tyao1">@ tyao1</a>)</li>
<li>Restore double invoking <code>useState()</code> and
<code>useReducer()</code> initializer functions in <em>StrictMode</em>
(<a href="https://redirect.github.com/facebook/react/pull/28248"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/28248/hovercard">#28248</a> by
<a class="user-mention notranslate" data-hovercard-type="user"
data-hovercard-url="/users/eps1lon/hovercard"
data-octo-click="hovercard-link-click"
data-octo-dimensions="link_type:self"
href="https://redirect.github.com/eps1lon">@ eps1lon</a>)</li>
<li>Reuse memoized result from first pass (<a
href="https://redirect.github.com/facebook/react/pull/25583"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/25583/hovercard">#25583</a> by
<a class="user-mention notranslate" data-hovercard-type="user"
data-hovercard-url="/users/acdlite/hovercard"
data-octo-click="hovercard-link-click"
data-octo-dimensions="link_type:self"
href="https://redirect.github.com/acdlite">@ acdlite</a>)</li>
<li>Fix <code>useId()</code> in <em>StrictMode</em> (<a
href="https://redirect.github.com/facebook/react/pull/25713"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/25713/hovercard">#25713</a> by
<a class="user-mention notranslate" data-hovercard-type="user"
data-hovercard-url="/users/gnoff/hovercard"
data-octo-click="hovercard-link-click"
data-octo-dimensions="link_type:self"
href="https://redirect.github.com/gnoff">@ gnoff</a>)</li>
<li>Add component name to <em>StrictMode</em> error messages (<a
href="https://redirect.github.com/facebook/react/pull/25718"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/25718/hovercard">#25718</a> by
<a class="user-mention notranslate" data-hovercard-type="user"
data-hovercard-url="/users/sammy-SC/hovercard"
data-octo-click="hovercard-link-click"
data-octo-dimensions="link_type:self"
href="https://redirect.github.com/sammy-SC">@ sammy-SC</a>)</li>
</ul>
</li>
<li>Add support for rendering BigInt (<a
href="https://redirect.github.com/facebook/react/pull/24580"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/24580/hovercard">#24580</a> by
<a class="user-mention notranslate" data-hovercard-type="user"
data-hovercard-url="/users/eps1lon/hovercard"
data-octo-click="hovercard-link-click"
data-octo-dimensions="link_type:self"
href="https://redirect.github.com/eps1lon">@ eps1lon</a>)</li>
<li><code>act()</code> no longer checks <code>shouldYield</code> which
can be inaccurate in test environments (<a
href="https://redirect.github.com/facebook/react/pull/26317"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/26317/hovercard">#26317</a> by
<a class="user-mention notranslate" data-hovercard-type="user"
data-hovercard-url="/users/acdlite/hovercard"
data-octo-click="hovercard-link-click"
data-octo-dimensions="link_type:self"
href="https://redirect.github.com/acdlite">@ acdlite</a>)</li>
<li>Warn when keys are spread with props (<a
href="https://redirect.github.com/facebook/react/pull/25697"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/25697/hovercard">#25697</a>, <a
href="https://redirect.github.com/facebook/react/pull/26080"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/26080/hovercard">#26080</a> by
<a class="user-mention notranslate" data-hovercard-type="user"
data-hovercard-url="/users/sebmarkbage/hovercard"
data-octo-click="hovercard-link-click"
data-octo-dimensions="link_type:self"
href="https://redirect.github.com/sebmarkbage">@ sebmarkbage</a> and <a
class="user-mention notranslate" data-hovercard-type="user"
data-hovercard-url="/users/kassens/hovercard"
data-octo-click="hovercard-link-click"
data-octo-dimensions="link_type:self"
href="https://redirect.github.com/kassens">@ kassens</a>)</li>
<li>Generate sourcemaps for production build artifacts (<a
href="https://redirect.github.com/facebook/react/pull/26446"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/26446/hovercard">#26446</a> by
<a class="user-mention notranslate" data-hovercard-type="user"
data-hovercard-url="/users/markerikson/hovercard"
data-octo-click="hovercard-link-click"
data-octo-dimensions="link_type:self"
href="https://redirect.github.com/markerikson">@ markerikson</a>)</li>
<li>Improve stack diffing algorithm (<a
href="https://redirect.github.com/facebook/react/pull/27132"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/27132/hovercard">#27132</a> by
<a class="user-mention notranslate" data-hovercard-type="user"
data-hovercard-url="/users/KarimP/hovercard"
data-octo-click="hovercard-link-click"
data-octo-dimensions="link_type:self"
href="https://redirect.github.com/KarimP">@ KarimP</a>)</li>
<li>Suspense throttling lowered from 500ms to 300ms (<a
href="https://redirect.github.com/facebook/react/pull/26803"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/26803/hovercard">#26803</a> by
<a class="user-mention notranslate" data-hovercard-type="user"
data-hovercard-url="/users/acdlite/hovercard"
data-octo-click="hovercard-link-click"
data-octo-dimensions="link_type:self"
href="https://redirect.github.com/acdlite">@ acdlite</a>)</li>
<li>Lazily propagate context changes (<a
href="https://redirect.github.com/facebook/react/pull/20890"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/20890/hovercard">#20890</a> by
<a class="user-mention notranslate" data-hovercard-type="user"
data-hovercard-url="/users/acdlite/hovercard"
data-octo-click="hovercard-link-click"
data-octo-dimensions="link_type:self"
href="https://redirect.github.com/acdlite">@ acdlite</a> and <a
class="user-mention notranslate" data-hovercard-type="user"
data-hovercard-url="/users/gnoff/hovercard"
data-octo-click="hovercard-link-click"
data-octo-dimensions="link_type:self"
href="https://redirect.github.com/gnoff">@ gnoff</a>)</li>
<li>Immediately rerender pinged fiber (<a
href="https://redirect.github.com/facebook/react/pull/25074"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/25074/hovercard">#25074</a> by
<a class="user-mention notranslate" data-hovercard-type="user"
data-hovercard-url="/users/acdlite/hovercard"
data-octo-click="hovercard-link-click"
data-octo-dimensions="link_type:self"
href="https://redirect.github.com/acdlite">@ acdlite</a>)</li>
<li>Move update scheduling to microtask (<a
href="https://redirect.github.com/facebook/react/pull/26512"
data-hovercard-type="pull_request"
data-hovercard-url="/facebook/react/pull/26512/hovercard">#26512</a> by
<a class="user-mention notranslate" data-hovercard-type="user"
data-hovercard-url="/users/acdlite/hovercard"
data-octo-click="hovercard-link-click"
data-octo-dimensions="link_type:self"
href="https://redirect.github.com/acdlite">@ acdlite</a>)</li>
<li>Consistently apply throttled retries (<a
href="https://redirect.github.com/facebook/…
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When React receives new input (via
setState, a Suspense promise resolution, and so on), it needs to ensure there's a rendering task associated with the update. Most of this happensensureRootIsScheduled.If a single event contains multiple updates, we end up running the scheduling code once per update. But this is wasteful because we really only need to run it once, at the end of the event (or in the case of flushSync, at the end of the scope function's execution).
So this PR moves the scheduling logic to happen in a microtask instead. In some cases, we will force it run earlier than that, like for
flushSync, but since updates are batched by default, it will almost always happen in the microtask. Even for discrete updates.In production, this should have no observable behavior difference. In a testing environment that uses
act, this should also not have a behavior difference because React will push these tasks to an internalactqueue.However, tests that do not use
actand do not simulate an actual production environment (like an e2e test) may be affected. For example, before this change, if a test were to callsetStateoutside ofactand then immediately calljest.runAllTimers(), the update would be synchronously applied. After this change, that will no longer work because the rendering task (a timer, in this case) isn't scheduled until after the microtask queue has run.I don't expect this to be an issue in practice because most people do not write their tests this way. They either use
act, or they write e2e-style tests.The biggest exception has been... our own internal test suite. Until recently, many of our tests were written in a way that accidentally relied on the updates being scheduled synchronously. Over the past few weeks, @tyao1 and I have gradually converted the test suite to use a new set of testing helpers that are resilient to this implementation detail.
(There are also some old Relay tests that were written in the style of React's internal test suite. Those will need to be fixed, too.)
The larger motivation behind this change, aside from a minor performance improvement, is we intend to use this new microtask to perform additional logic that doesn't yet exist. Like inferring the priority of a custom event.