1## 19.2.7 (June 1, 2026)23### React Server Components45- Fixed missing `FormData` entries in Server Actions which regressed in 19.2.6 (@unstubbable [#36566](https://github.com/facebook/react/pull/36566))67## 19.2.6 (May 6, 2026)89### React Server Components1011- Type hardening and performance improvements (@eps1lon, @unstubbable [#36425](https://github.com/facebook/react/pull/36425))1213## 19.2.5 (March 18, 2026)1415### React Server Components1617- Add more cycle protections (@eps1lon, @unstubbable [#36236](https://github.com/facebook/react/pull/36236))1819## 19.2.4 (Jan 26, 2026)2021### React Server Components2223- Add more DoS mitigations to Server Actions, and harden Server Components (@gnoff, @lubieowoce, @sebmarkbage, @unstubbable [#35632](https://github.com/facebook/react/pull/35632))2425## 19.2.3 (Dec 11, 2025)2627### React Server Components2829- Add extra loop protection to React Server Functions (@sebmarkbage [#35351](https://github.com/facebook/react/pull/35351))3031## 19.2.2 (Dec 11, 2025)3233### React Server Components3435- Move `react-server-dom-webpack/*.unbundled` to private `react-server-dom-unbundled` (@eps1lon [#35290](https://github.com/facebook/react/pull/35290))36- Patch Promise cycles and toString on Server Functions (@sebmarkbage, @unstubbable [#35289](https://github.com/facebook/react/pull/35289), [#35345](https://github.com/facebook/react/pull/35345))3738## 19.2.1 (Dec 3, 2025)3940### React Server Components4142- Bring React Server Component fixes to Server Actions (@sebmarkbage [#35277](https://github.com/facebook/react/pull/35277))4344## 19.2.0 (October 1st, 2025)4546Below is a list of all new features, APIs, and bug fixes.4748Read the [React 19.2 release post](https://react.dev/blog/2025/10/01/react-19-2) for more information.4950### New React Features5152- [`<Activity>`](https://react.dev/reference/react/Activity): A new API to hide and restore the UI and internal state of its children.53- [`useEffectEvent`](https://react.dev/reference/react/useEffectEvent) is a React Hook that lets you extract non-reactive logic into an [Effect Event](https://react.dev/learn/separating-events-from-effects#declaring-an-effect-event).54- [`cacheSignal`](https://react.dev/reference/react/cacheSignal) (for RSCs) lets your know when the `cache()` lifetime is over.55- [React Performance tracks](https://react.dev/reference/dev-tools/react-performance-tracks) appear on the Performance panel’s timeline in your browser developer tools5657### New React DOM Features5859- Added resume APIs for partial pre-rendering with Web Streams:60  - [`resume`](https://react.dev/reference/react-dom/server/resume): to resume a prerender to a stream.61  - [`resumeAndPrerender`](https://react.dev/reference/react-dom/static/resumeAndPrerender): to resume a prerender to HTML.62- Added resume APIs for partial pre-rendering with Node Streams:63  - [`resumeToPipeableStream`](https://react.dev/reference/react-dom/server/resumeToPipeableStream): to resume a prerender to a stream.64  - [`resumeAndPrerenderToNodeStream`](https://react.dev/reference/react-dom/static/resumeAndPrerenderToNodeStream): to resume a prerender to HTML.65- Updated [`prerender`](https://react.dev/reference/react-dom/static/prerender) APIs to return a `postponed` state that can be passed to the `resume` APIs.6667### Notable changes6869- React DOM now batches suspense boundary reveals, matching the behavior of client side rendering. This change is especially noticeable when animating the reveal of Suspense boundaries e.g. with the upcoming `<ViewTransition>` Component. React will batch as much reveals as possible before the first paint while trying to hit popular first-contentful paint metrics.70- Add Node Web Streams (`prerender`, `renderToReadableStream`) to server-side-rendering APIs for Node.js71- Use underscore instead of `:` IDs generated by useId7273### All Changes7475#### React7677- `<Activity />` was developed over many years, starting before `ClassComponent.setState` (@acdlite @sebmarkbage and many others)78- Stringify context as "SomeContext" instead of "SomeContext.Provider" (@kassens [#33507](https://github.com/facebook/react/pull/33507))79- Include stack of cause of React instrumentation errors with `%o` placeholder (@eps1lon [#34198](https://github.com/facebook/react/pull/34198))80- Fix infinite `useDeferredValue` loop in popstate event (@acdlite [#32821](https://github.com/facebook/react/pull/32821))81- Fix a bug when an initial value was passed to `useDeferredValue` (@acdlite [#34376](https://github.com/facebook/react/pull/34376))82- Fix a crash when submitting forms with Client Actions (@sebmarkbage [#33055](https://github.com/facebook/react/pull/33055))83- Hide/unhide the content of dehydrated suspense boundaries if they resuspend (@sebmarkbage [#32900](https://github.com/facebook/react/pull/32900))84- Avoid stack overflow on wide trees during Hot Reload (@sophiebits [#34145](https://github.com/facebook/react/pull/34145))85- Improve Owner and Component stacks in various places (@sebmarkbage, @eps1lon: [#33629](https://github.com/facebook/react/pull/33629), [#33724](https://github.com/facebook/react/pull/33724), [#32735](https://github.com/facebook/react/pull/32735), [#33723](https://github.com/facebook/react/pull/33723))86- Add `cacheSignal` (@sebmarkbage [#33557](https://github.com/facebook/react/pull/33557))8788#### React DOM8990- Block on Suspensey Fonts during reveal of server-side-rendered content (@sebmarkbage [#33342](https://github.com/facebook/react/pull/33342))91- Use underscore instead of `:` for IDs generated by `useId` (@sebmarkbage, @eps1lon: [#32001](https://github.com/facebook/react/pull/32001), [https://github.com/facebook/react/pull/33342](https://github.com/facebook/react/pull/33342)[#33099](https://github.com/facebook/react/pull/33099), [#33422](https://github.com/facebook/react/pull/33422))92- Stop warning when ARIA 1.3 attributes are used (@Abdul-Omira [#34264](https://github.com/facebook/react/pull/34264))93- Allow `nonce` to be used on hoistable styles (@Andarist [#32461](https://github.com/facebook/react/pull/32461))94- Warn for using a React owned node as a Container if it also has text content (@sebmarkbage [#32774](https://github.com/facebook/react/pull/32774))95- s/HTML/text for for error messages if text hydration mismatches (@rickhanlonii [#32763](https://github.com/facebook/react/pull/32763))96- Fix a bug with `React.use` inside `React.lazy`\-ed Component (@hi-ogawa [#33941](https://github.com/facebook/react/pull/33941))97- Enable the `progressiveChunkSize` option for server-side-rendering APIs (@sebmarkbage [#33027](https://github.com/facebook/react/pull/33027))98- Fix a bug with deeply nested Suspense inside Suspense fallback when server-side-rendering (@gnoff [#33467](https://github.com/facebook/react/pull/33467))99- Avoid hanging when suspending after aborting while rendering (@gnoff [#34192](https://github.com/facebook/react/pull/34192))100- Add Node Web Streams to server-side-rendering APIs for Node.js (@sebmarkbage [#33475](https://github.com/facebook/react/pull/33475))101102#### React Server Components103104- Preload `<img>` and `<link>` using hints before they're rendered (@sebmarkbage [#34604](https://github.com/facebook/react/pull/34604))105- Log error if production elements are rendered during development (@eps1lon [#34189](https://github.com/facebook/react/pull/34189))106- Fix a bug when returning a Temporary reference (e.g. a Client Reference) from Server Functions (@sebmarkbage [#34084](https://github.com/facebook/react/pull/34084), @denk0403 [#33761](https://github.com/facebook/react/pull/33761))107- Pass line/column to `filterStackFrame` (@eps1lon [#33707](https://github.com/facebook/react/pull/33707))108- Support Async Modules in Turbopack Server References (@lubieowoce [#34531](https://github.com/facebook/react/pull/34531))109- Add support for .mjs file extension in Webpack (@jennyscript [#33028](https://github.com/facebook/react/pull/33028))110- Fix a wrong missing key warning (@unstubbable [#34350](https://github.com/facebook/react/pull/34350))111- Make console log resolve in predictable order (@sebmarkbage [#33665](https://github.com/facebook/react/pull/33665))112113#### React Reconciler114115- [createContainer](https://github.com/facebook/react/blob/v19.2.0/packages/react-reconciler/src/ReactFiberReconciler.js#L255-L261) and [createHydrationContainer](https://github.com/facebook/react/blob/v19.2.0/packages/react-reconciler/src/ReactFiberReconciler.js#L305-L312) had their parameter order adjusted after `on*` handlers to account for upcoming experimental APIs116117## 19.1.8 (June 1, 2026)118119### React Server Components120121- Fixed missing `FormData` entries in Server Actions which regressed in 19.1.7 (@unstubbable [#36567](https://github.com/facebook/react/pull/36567))122123## 19.1.7 (May 6, 2026)124125### React Server Components126127- Type hardening and performance improvements (@eps1lon, @unstubbable [#36425](https://github.com/facebook/react/pull/36425))128129## 19.1.6 (March 18, 2026)130131### React Server Components132133- Add more cycle protections (@eps1lon, @unstubbable [#36236](https://github.com/facebook/react/pull/36236))134135## 19.1.5 (Jan 26, 2026)136137### React Server Components138139- Add more DoS mitigations to Server Actions, and harden Server Components (@gnoff, @lubieowoce, @sebmarkbage, @unstubbable [#35632](https://github.com/facebook/react/pull/35632))140141## 19.1.4 (Dec 11, 2025)142143### React Server Components144145- Add extra loop protection to React Server Functions (@sebmarkbage [#35351](https://github.com/facebook/react/pull/35351))146147## 19.1.3 (Dec 11, 2025)148149### React Server Components150151- Move `react-server-dom-webpack/*.unbundled` to private `react-server-dom-unbundled` (@eps1lon [#35290](https://github.com/facebook/react/pull/35290))152- Patch Promise cycles and toString on Server Functions (@sebmarkbage, @unstubbable [#35289](https://github.com/facebook/react/pull/35289), [#35345](https://github.com/facebook/react/pull/35345))153154## 19.1.2 (Dec 3, 2025)155156### React Server Components157158- Bring React Server Component fixes to Server Actions (@sebmarkbage [#35277](https://github.com/facebook/react/pull/35277))159160## 19.1.1 (July 28, 2025)161162### React163* Fixed Owner Stacks to work with ES2015 function.name semantics ([#33680](https://github.com/facebook/react/pull/33680) by @hoxyq)164165## 19.1.0 (March 28, 2025)166167### Owner Stack168169An 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.170171* 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.172* The [captureOwnerStack API](https://react.dev/reference/react/captureOwnerStack) 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. [#29923](https://github.com/facebook/react/pull/29923), [#32353](https://github.com/facebook/react/pull/32353), [#30306](https://github.com/facebook/react/pull/30306),173[#32538](https://github.com/facebook/react/pull/32538), [#32529](https://github.com/facebook/react/pull/32529), [#32538](https://github.com/facebook/react/pull/32538)174175### React176* Enhanced support for Suspense boundaries to be used anywhere, including the client, server, and during hydration. [#32069](https://github.com/facebook/react/pull/32069), [#32163](https://github.com/facebook/react/pull/32163), [#32224](https://github.com/facebook/react/pull/32224), [#32252](https://github.com/facebook/react/pull/32252)177* Reduced unnecessary client rendering through improved hydration scheduling [#31751](https://github.com/facebook/react/pull/31751)178* Increased priority of client rendered Suspense boundaries [#31776](https://github.com/facebook/react/pull/31776)179* Fixed frozen fallback states by rendering unfinished Suspense boundaries on the client. [#31620](https://github.com/facebook/react/pull/31620)180* Reduced garbage collection pressure by improving Suspense boundary retries. [#31667](https://github.com/facebook/react/pull/31667)181* Fixed erroneous “Waiting for Paint” log when the passive effect phase was not delayed [#31526](https://github.com/facebook/react/pull/31526)182* Fixed a regression causing key warnings for flattened positional children in development mode. [#32117](https://github.com/facebook/react/pull/32117)183* Updated `useId` to use valid CSS selectors, changing format from `:r123:` to `«r123»`. [#32001](https://github.com/facebook/react/pull/32001)184* Added a dev-only warning for null/undefined created in useEffect, useInsertionEffect, and useLayoutEffect. [#32355](https://github.com/facebook/react/pull/32355)185* Fixed a bug where dev-only methods were exported in production builds. React.act is no longer available in production builds. [#32200](https://github.com/facebook/react/pull/32200)186* Improved consistency across prod and dev to improve compatibility with Google Closure Compiler and bindings [#31808](https://github.com/facebook/react/pull/31808)187* Improve passive effect scheduling for consistent task yielding. [#31785](https://github.com/facebook/react/pull/31785)188* Fixed asserts in React Native when passChildrenWhenCloningPersistedNodes is enabled for OffscreenComponent rendering. [#32528](https://github.com/facebook/react/pull/32528)189* Fixed component name resolution for Portal [#32640](https://github.com/facebook/react/pull/32640)190* Added support for beforetoggle and toggle events on the dialog element. [#32479](https://github.com/facebook/react/pull/32479)191192### React DOM193* Fixed double warning when the `href` attribute is an empty string [#31783](https://github.com/facebook/react/pull/31783)194 * Fixed an edge case where `getHoistableRoot()` didn’t work properly when the container was a Document [#32321](https://github.com/facebook/react/pull/32321)195* Removed support for using HTML comments (e.g. `<!-- -->`) as a DOM container. [#32250](https://github.com/facebook/react/pull/32250)196* Added support for `<script>` and `<template>` tags to be nested within `<select>` tags. [#31837](https://github.com/facebook/react/pull/31837)197* Fixed responsive images to be preloaded as HTML instead of headers [#32445](https://github.com/facebook/react/pull/32445)198199### use-sync-external-store200* Added `exports` field to `package.json` for `use-sync-external-store` to support various entrypoints. [#25231](https://github.com/facebook/react/pull/25231)201202### React Server Components203* Added `unstable_prerender`, a new experimental API for prerendering React Server Components on the server [#31724](https://github.com/facebook/react/pull/31724)204* Fixed an issue where streams would hang when receiving new chunks after a global error [#31840](https://github.com/facebook/react/pull/31840), [#31851](https://github.com/facebook/react/pull/31851)205* Fixed an issue where pending chunks were counted twice. [#31833](https://github.com/facebook/react/pull/31833)206* Added support for streaming in edge environments [#31852](https://github.com/facebook/react/pull/31852)207* Added support for sending custom error names from a server so that they are available in the client for console replaying. [#32116](https://github.com/facebook/react/pull/32116)208* Updated the server component wire format to remove IDs for hints and console.log because they have no return value [#31671](https://github.com/facebook/react/pull/31671)209* Exposed `registerServerReference` in client builds to handle server references in different environments. [#32534](https://github.com/facebook/react/pull/32534)210* Added react-server-dom-parcel package which integrates Server Components with the [Parcel bundler](https://parceljs.org/) [#31725](https://github.com/facebook/react/pull/31725), [#32132](https://github.com/facebook/react/pull/32132), [#31799](https://github.com/facebook/react/pull/31799), [#32294](https://github.com/facebook/react/pull/32294), [#31741](https://github.com/facebook/react/pull/31741)211212## 19.0.7 (June 1, 2026)213214### React Server Components215216- Fixed missing `FormData` entries in Server Actions which regressed in 19.0.6 (@unstubbable [#36568](https://github.com/facebook/react/pull/36568))217218## 19.0.6 (May 6, 2026)219220### React Server Components221222- Type hardening and performance improvements (@eps1lon, @unstubbable [#36425](https://github.com/facebook/react/pull/36425))223224## 19.0.5 (March 18, 2026)225226### React Server Components227228- Add more cycle protections (@eps1lon, @unstubbable [#36236](https://github.com/facebook/react/pull/36236))229230## 19.0.4 (Jan 26, 2026)231232### React Server Components233234- Add more DoS mitigations to Server Actions, and harden Server Components (@gnoff, @lubieowoce, @sebmarkbage, @unstubbable [#35632](https://github.com/facebook/react/pull/35632))235236## 19.0.3 (Dec 11, 2025)237238### React Server Components239240- Add extra loop protection to React Server Functions (@sebmarkbage [#35351](https://github.com/facebook/react/pull/35351))241242## 19.0.2 (Dec 11, 2025)243244### React Server Components245246- Patch Promise cycles and toString on Server Functions (@sebmarkbage, @unstubbable [#35289](https://github.com/facebook/react/pull/35289), [#35345](https://github.com/facebook/react/pull/35345))247248## 19.0.1 (Dec 3, 2025)249250### React Server Components251252- Bring React Server Component fixes to Server Actions (@sebmarkbage [#35277](https://github.com/facebook/react/pull/35277))253254## 19.0.0 (December 5, 2024)255256Below is a list of all new features, APIs, deprecations, and breaking changes. Read [React 19 release post](https://react.dev/blog/2024/04/25/react-19) and [React 19 upgrade guide](https://react.dev/blog/2024/04/25/react-19-upgrade-guide) for more information.257258> 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 19.259260### New Features261262#### React263264* Actions: `startTransition` can now accept async functions. Functions passed to `startTransition` 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 `fetch()` in the pending state, and provides support for error handling, and optimistic updates.  265* `useActionState`: 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 `action` prop to support progressive enhancement in forms.  266* `useOptimistic`: 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.  267* `use`: is a new API that allows reading resources in render. In React 19, `use` accepts a promise or Context. If provided a promise, `use` will suspend until a value is resolved. `use` can only be used in render but can be called conditionally.  268* `ref` as a prop: Refs can now be used as props, removing the need for `forwardRef`.  269* **Suspense sibling pre-warming**: 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.270271#### React DOM Client272273* `<form> action` prop: Form Actions allow you to manage forms automatically and integrate with `useFormStatus`. When a `<form> action` succeeds, React will automatically reset the form for uncontrolled components. The form can be reset manually with the new `requestFormReset` API.  274* `<button> and <input> formAction` prop: Actions can be passed to the `formAction` prop to configure form submission behavior. This allows using different Actions depending on the input.  275* `useFormStatus`: is a new hook that provides the status of the parent `<form> action`, as if the form was a Context provider. The hook returns the values: `pending`, `data`, `method`, and `action`.  276* Support for Document Metadata: We’ve added support for rendering document metadata tags in components natively. React will automatically hoist them into the `<head>` section of the document.  277* Support for Stylesheets: React 19 will ensure stylesheets are inserted into the `<head>` on the client before revealing the content of a Suspense boundary that depends on that stylesheet.  278* Support for async scripts: Async scripts can be rendered anywhere in the component tree and React will handle ordering and deduplication.  279* Support for preloading resources: React 19 ships with `preinit`, `preload`, `prefetchDNS`, and `preconnect` 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.280281#### React DOM Server282283* Added `prerender` and `prerenderToNodeStream` APIs for static site generation. They are designed to work with streaming environments like Node.js Streams and Web Streams. Unlike `renderToString`, they wait for data to load for HTML generation.284285#### React Server Components286287* 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 [docs](https://19.react.dev/reference/rsc/server-components) for how to support React Server Components.288289### Deprecations290291* Deprecated: `element.ref` access: React 19 supports ref as a prop, so we’re deprecating `element.ref` in favor of `element.props.ref`. Accessing will result in a warning.  292* `react-test-renderer`: 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  [@testing-library/react](https://testing-library.com/docs/react-testing-library/intro/) or [@testing-library/react-native](https://testing-library.com/docs/react-native-testing-library/intro)293294### Breaking Changes295296React 19 brings in a number of breaking changes, including the removals of long-deprecated APIs. We recommend first upgrading to `18.3.1`, where we've added additional deprecation warnings. Check out the [upgrade guide](https://19.react.dev/blog/2024/04/25/react-19-upgrade-guide) for more details and guidance on codemodding.297298### React299300* New JSX Transform is now required: We introduced [a new JSX transform](https://legacy.reactjs.org/blog/2020/09/22/introducing-the-new-jsx-transform.html) 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.  301* 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 `onUncaughtError` and `onCaughtError` methods to `createRoot` and `hydrateRoot` to customize this error handling.  302* Removed: `propTypes`: Using `propTypes` will now be silently ignored. If required, we recommend migrating to TypeScript or another type-checking solution.  303* Removed: `defaultProps` for functions: ES6 default parameters can be used in place. Class components continue to support `defaultProps` since there is no ES6 alternative.  304* Removed: `contextTypes` and `getChildContext`: Legacy Context for class components has been removed in favor of the `contextType` API.  305* Removed: string refs: Any usage of string refs need to be migrated to ref callbacks.   306* Removed: Module pattern factories: A rarely used pattern that can be migrated to regular functions.  307* Removed: `React.createFactory`: Now that JSX is broadly supported, all `createFactory` usage can be migrated to JSX components.  308* Removed: `react-test-renderer/shallow`: This has been a re-export of [react-shallow-renderer](https://github.com/enzymejs/react-shallow-renderer) since React 18\. If needed, you can continue to use the third-party package directly. We recommend using [@testing-library/react](https://testing-library.com/docs/react-testing-library/intro/) or [@testing-library/react-native](https://testing-library.com/docs/react-native-testing-library/intro) instead.309310#### React DOM311312* Removed: `react-dom/test-utils`: We’ve moved `act` from `react-dom/test-utils` to react. All other utilities have been removed.   313* Removed: `ReactDOM`.`render`, `ReactDOM`.`hydrate`: These have been removed in favor of the concurrent equivalents: `ReactDOM`.`createRoot` and `ReactDOM.hydrateRoot`.  314* Removed: `unmountComponentAtNode`: Removed in favor of `root.unmount()`.  315* Removed: `ReactDOM`.`findDOMNode`: You can replace `ReactDOM`.`findDOMNode` with DOM Refs.316317### Notable Changes318319#### React320321* `<Context>` as a provider: You can now render `<Context>` as a provider instead of `<Context.Provider>`.  322* Cleanup functions for refs: When the component unmounts, React will call the cleanup function returned from the ref callback.  323* `useDeferredValue` initial value argument: When provided, `useDeferredValue` will return the initial value for the initial render of a component, then schedule a re-render in the background with the `deferredValue` returned.  324* Support for Custom Elements: React 19 now passes all tests on [Custom Elements Everywhere](https://custom-elements-everywhere.com/).  325* StrictMode changes: `useMemo` and `useCallback` 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.  326* UMD builds removed: To load React 19 with a script tag, we recommend using an ESM-based CDN such as [esm.sh](http://esm.sh).327328#### React DOM329330* Diffs for hydration errors: In the case of a mismatch, React 19 logs a single error with a diff of the mismatched content.  331* 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. 332333### TypeScript Changes334335The most common changes can be codemodded with `npx types-react-codemod@latest preset-19 ./path-to-your-react-ts-files`.336337* Removed deprecated TypeScript types:   338  * `ReactChild` (replacement: `React.ReactElement | number | string)`  339  * `ReactFragment` (replacement: `Iterable<React.ReactNode>`)  340  * `ReactNodeArray` (replacement: `ReadonlyArray<React.ReactNode>`)  341  * `ReactText` (replacement: `number | string`)  342  * `VoidFunctionComponent` (replacement: `FunctionComponent`)  343  * `VFC` (replacement: `FC`)  344  * Moved to `prop-types`: `Requireable`, `ValidationMap`, `Validator`, `WeakValidationMap`  345  * Moved to `create-react-class`: `ClassicComponentClass`, `ClassicComponent`, `ClassicElement`, `ComponentSpec`, `Mixin`, `ReactChildren`, `ReactHTML`, `ReactSVG`, `SFCFactory`  346* 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.   347* Require initial argument to `useRef`: The initial argument is now required to match `useState`, `createContext` etc  348* Refs are mutable by default: Ref objects returned from `useRef()` 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.  349* Strict `ReactElement` typing: The props of React elements now default to `unknown` instead of `any` if the element is typed as `ReactElement`  350* JSX namespace in TypeScript: The global `JSX` namespace is removed to improve interoperability with other libraries using JSX. Instead, the JSX namespace is available from the React package: `import { JSX } from 'react'`  351* Better `useReducer` typings: Most `useReducer` usage should not require explicit type arguments.  352  For example,  353  ```diff354  -useReducer<React.Reducer<State, Action>>(reducer)355  +useReducer(reducer)356  ```357  or358  ```diff359  -useReducer<React.Reducer<State, Action>>(reducer)360  +useReducer<State, Action>(reducer)361  ```362363### All Changes364365#### React366367* Add support for async Actions ([\#26621](https://github.com/facebook/react/pull/26621), [\#26726](https://github.com/facebook/react/pull/26726), [\#28078](https://github.com/facebook/react/pull/28078), [\#28097](https://github.com/facebook/react/pull/28097), [\#29226](https://github.com/facebook/react/pull/29226), [\#29618](https://github.com/facebook/react/pull/29618), [\#29670](https://github.com/facebook/react/pull/29670), [\#26716](https://github.com/facebook/react/pull/26716) by [@acdlite](https://github.com/acdlite) and [@sebmarkbage](https://github.com/sebmarkbage))  368* Add `useActionState()` hook to update state based on the result of a Form Action ([\#27270](https://github.com/facebook/react/pull/27270), [\#27278](https://github.com/facebook/react/pull/27278), [\#27309](https://github.com/facebook/react/pull/27309), [\#27302](https://github.com/facebook/react/pull/27302), [\#27307](https://github.com/facebook/react/pull/27307), [\#27366](https://github.com/facebook/react/pull/27366), [\#27370](https://github.com/facebook/react/pull/27370), [\#27321](https://github.com/facebook/react/pull/27321), [\#27374](https://github.com/facebook/react/pull/27374), [\#27372](https://github.com/facebook/react/pull/27372), [\#27397](https://github.com/facebook/react/pull/27397), [\#27399](https://github.com/facebook/react/pull/27399), [\#27460](https://github.com/facebook/react/pull/27460), [\#28557](https://github.com/facebook/react/pull/28557), [\#27570](https://github.com/facebook/react/pull/27570), [\#27571](https://github.com/facebook/react/pull/27571), [\#28631](https://github.com/facebook/react/pull/28631), [\#28788](https://github.com/facebook/react/pull/28788), [\#29694](https://github.com/facebook/react/pull/29694), [\#29695](https://github.com/facebook/react/pull/29695), [\#29694](https://github.com/facebook/react/pull/29694), [\#29665](https://github.com/facebook/react/pull/29665), [\#28232](https://github.com/facebook/react/pull/28232), [\#28319](https://github.com/facebook/react/pull/28319) by [@acdlite](https://github.com/acdlite), [@eps1lon](https://github.com/eps1lon), and [@rickhanlonii](https://github.com/rickhanlonii))  369* Add `use()` API to read resources in render ([\#25084](https://github.com/facebook/react/pull/25084), [\#25202](https://github.com/facebook/react/pull/25202), [\#25207](https://github.com/facebook/react/pull/25207), [\#25214](https://github.com/facebook/react/pull/25214), [\#25226](https://github.com/facebook/react/pull/25226), [\#25247](https://github.com/facebook/react/pull/25247), [\#25539](https://github.com/facebook/react/pull/25539), [\#25538](https://github.com/facebook/react/pull/25538), [\#25537](https://github.com/facebook/react/pull/25537), [\#25543](https://github.com/facebook/react/pull/25543), [\#25561](https://github.com/facebook/react/pull/25561), [\#25620](https://github.com/facebook/react/pull/25620), [\#25615](https://github.com/facebook/react/pull/25615), [\#25922](https://github.com/facebook/react/pull/25922), [\#25641](https://github.com/facebook/react/pull/25641), [\#25634](https://github.com/facebook/react/pull/25634), [\#26232](https://github.com/facebook/react/pull/26232), [\#26536](https://github.com/facebook/react/pull/26535), [\#26739](https://github.com/facebook/react/pull/26739), [\#28233](https://github.com/facebook/react/pull/28233) by [@acdlite](https://github.com/acdlite), [@MofeiZ](https://github.com/mofeiZ), [@sebmarkbage](https://github.com/sebmarkbage), [@sophiebits](https://github.com/sophiebits), [@eps1lon](https://github.com/eps1lon), and [@hansottowirtz](https://github.com/hansottowirtz))  370* Add `useOptimistic()` hook to display mutated state optimistically during an async mutation ([\#26740](https://github.com/facebook/react/pull/26740), [\#26772](https://github.com/facebook/react/pull/26772), [\#27277](https://github.com/facebook/react/pull/27277), [\#27453](https://github.com/facebook/react/pull/27453), [\#27454](https://github.com/facebook/react/pull/27454), [\#27936](https://github.com/facebook/react/pull/27936) by [@acdlite](https://github.com/acdlite))  371* Added an `initialValue` argument to `useDeferredValue()` hook ([\#27500](https://github.com/facebook/react/pull/27500), [\#27509](https://github.com/facebook/react/pull/27509), [\#27512](https://github.com/facebook/react/pull/27512), [\#27888](https://github.com/facebook/react/pull/27888), [\#27550](https://github.com/facebook/react/pull/27550) by [@acdlite](https://github.com/acdlite))  372* Support refs as props, warn on `element.ref` access ([\#28348](https://github.com/facebook/react/pull/28348), [\#28464](https://github.com/facebook/react/pull/28464), [\#28731](https://github.com/facebook/react/pull/28731) by [@acdlite](https://github.com/acdlite))  373* Support Custom Elements ([\#22184](https://github.com/facebook/react/pull/22184), [\#26524](https://github.com/facebook/react/pull/26524), [\#26523](https://github.com/facebook/react/pull/26523), [\#27511](https://github.com/facebook/react/pull/27511), [\#24541](https://github.com/facebook/react/pull/24541) by [@josepharhar](https://github.com/josepharhar), [@sebmarkbage](https://github.com/sebmarkbage), [@gnoff](https://github.com/gnoff) and [@eps1lon](https://github.com/eps1lon))  374* Add ref cleanup function ([\#25686](https://github.com/facebook/react/pull/25686), [\#28883](https://github.com/facebook/react/pull/28883), [\#28910](https://github.com/facebook/react/pull/28910)  by [@sammy-SC](https://github.com/sammy-SC), [@jackpope](https://github.com/jackpope), and [@kassens](https://github.com/kassens))  375* Sibling pre-rendering replaced by sibling pre-warming ([\#26380](https://github.com/facebook/react/pull/26380), [\#26549](https://github.com/facebook/react/pull/26549), [\#30761](https://github.com/facebook/react/pull/30761), [\#30800](https://github.com/facebook/react/pull/30800), [\#30762](https://github.com/facebook/react/pull/30762), [\#30879](https://github.com/facebook/react/pull/30879), [\#30934](https://github.com/facebook/react/pull/30934), [\#30952](https://github.com/facebook/react/pull/30952), [\#31056](https://github.com/facebook/react/pull/31056), [\#31452](https://github.com/facebook/react/pull/31452) by [@sammy-SC](https://github.com/sammy-SC), [@acdlite](https://github.com/acdlite), [@gnoff](https://github.com/gnoff), [@jackpope](https://github.com/jackpope), [@rickhanlonii](https://github.com/rickhanlonii))  376* Don’t rethrow errors at the root ([\#28627](https://github.com/facebook/react/pull/28627), [\#28641](https://github.com/facebook/react/pull/28641) by [@sebmarkbage](https://github.com/sebmarkbage))  377* Batch sync discrete, continuous, and default lanes ([\#25700](https://github.com/facebook/react/pull/25700) by [@tyao1](https://github.com/tyao1))  378* Switch `<Context>` to mean `<Context.Provider>` ([\#28226](https://github.com/facebook/react/pull/28226) by [@gaearon](https://github.com/gaearon))  379* Changes to *StrictMode*  380  * Handle `info`, `group`, and `groupCollapsed` in *StrictMode* logging ([\#25172](https://github.com/facebook/react/pull/25172) by [@timneutkens](https://github.com/timneutkens))  381  * Refs are now attached/detached/attached in *StrictMode* ([\#25049](https://github.com/facebook/react/pull/25049) by [@sammy-SC](https://github.com/sammy-SC))  382  * Fix `useSyncExternalStore()` hydration in *StrictMode* ([\#26791](https://github.com/facebook/react/pull/26791) by [@sophiebits](https://github.com/sophiebits))  383  * Always trigger `componentWillUnmount()` in *StrictMode* ([\#26842](https://github.com/facebook/react/pull/26842) by [@tyao1](https://github.com/tyao1))  384  * Restore double invoking `useState()` and `useReducer()` initializer functions in *StrictMode* ([\#28248](https://github.com/facebook/react/pull/28248) by [@eps1lon](https://github.com/eps1lon))  385  * Reuse memoized result from first pass ([\#25583](https://github.com/facebook/react/pull/25583) by [@acdlite](https://github.com/acdlite))  386  * Fix `useId()` in *StrictMode* ([\#25713](https://github.com/facebook/react/pull/25713) by [@gnoff](https://github.com/gnoff))  387  * Add component name to *StrictMode* error messages ([\#25718](https://github.com/facebook/react/pull/25718) by [@sammy-SC](https://github.com/sammy-SC))  388* Add support for rendering BigInt ([\#24580](https://github.com/facebook/react/pull/24580) by [@eps1lon](https://github.com/eps1lon))  389* `act()` no longer checks `shouldYield` which can be inaccurate in test environments ([\#26317](https://github.com/facebook/react/pull/26317) by [@acdlite](https://github.com/acdlite))  390* Warn when keys are spread with props ([\#25697](https://github.com/facebook/react/pull/25697), [\#26080](https://github.com/facebook/react/pull/26080) by [@sebmarkbage](https://github.com/sebmarkbage) and [@kassens](https://github.com/kassens))  391* Generate sourcemaps for production build artifacts ([\#26446](https://github.com/facebook/react/pull/26446) by [@markerikson](https://github.com/markerikson))  392* Improve stack diffing algorithm ([\#27132](https://github.com/facebook/react/pull/27132) by [@KarimP](https://github.com/KarimP))  393* Suspense throttling lowered from 500ms to 300ms ([\#26803](https://github.com/facebook/react/pull/26803) by [@acdlite](https://github.com/acdlite))  394* Lazily propagate context changes ([\#20890](https://github.com/facebook/react/pull/20890) by [@acdlite](https://github.com/acdlite) and [@gnoff](https://github.com/gnoff))  395* Immediately rerender pinged fiber ([\#25074](https://github.com/facebook/react/pull/25074) by [@acdlite](https://github.com/acdlite))  396* Move update scheduling to microtask ([\#26512](https://github.com/facebook/react/pull/26512) by [@acdlite](https://github.com/acdlite))  397* Consistently apply throttled retries ([\#26611](https://github.com/facebook/react/pull/26611), [\#26802](https://github.com/facebook/react/pull/26802) by [@acdlite](https://github.com/acdlite))  398* Suspend Thenable/Lazy if it's used in React.Children ([\#28284](https://github.com/facebook/react/pull/28284) by [@sebmarkbage](https://github.com/sebmarkbage))  399* Detect infinite update loops caused by render phase updates ([\#26625](https://github.com/facebook/react/pull/26625) by [@acdlite](https://github.com/acdlite))  400* Update conditional hooks warning ([\#29626](https://github.com/facebook/react/pull/29626) by [@sophiebits](https://github.com/sophiebits))  401* Update error URLs to go to new docs ([\#27240](https://github.com/facebook/react/pull/27240) by [@rickhanlonii](https://github.com/rickhanlonii))  402* Rename the `react.element` symbol to `react.transitional.element` ([\#28813](https://github.com/facebook/react/pull/28813) by [@sebmarkbage](https://github.com/sebmarkbage))  403* Fix crash when suspending in shell during `useSyncExternalStore()` re-render ([\#27199](https://github.com/facebook/react/pull/27199) by [@acdlite](https://github.com/acdlite))  404* Fix incorrect “detected multiple renderers" error in tests ([\#22797](https://github.com/facebook/react/pull/22797) by [@eps1lon](https://github.com/eps1lon))  405* Fix bug where effect cleanup may be called twice after bailout ([\#26561](https://github.com/facebook/react/pull/26561) by [@acdlite](https://github.com/acdlite))  406* Fix suspending in shell during discrete update ([\#25495](https://github.com/facebook/react/pull/25495) by [@acdlite](https://github.com/acdlite))  407* Fix memory leak after repeated setState bailouts ([\#25309](https://github.com/facebook/react/pull/25309) by [@acdlite](https://github.com/acdlite))  408* Fix `useSyncExternalStore()` dropped update when state is dispatched in render phase ([\#25578](https://github.com/facebook/react/pull/25578) by [@pandaiolo](https://github.com/pandaiolo))  409* Fix logging when rendering a lazy fragment ([\#30372](https://github.com/facebook/react/pull/30372) by [@tom-sherman](https://github.com/tom-sherman))  410* Remove string refs ([\#25383](https://github.com/facebook/react/pull/25383), [\#28322](https://github.com/facebook/react/pull/28322) by [@eps1lon](https://github.com/eps1lon) and [@acdlite](https://github.com/acdlite))  411* Remove Legacy Context (\#30319 by [@kassens](https://github.com/kassens))  412* Remove `RefreshRuntime.findAffectedHostInstances` ([\#30538](https://github.com/facebook/react/pull/30538) by [@gaearon](https://github.com/gaearon))  413* Remove client caching from `cache()` API ([\#27977](https://github.com/facebook/react/pull/27977), [\#28250](https://github.com/facebook/react/pull/28250) by [@acdlite](https://github.com/acdlite) and [@gnoff](https://github.com/gnoff))  414* Remove `propTypes` ([\#28324](https://github.com/facebook/react/pull/28324), [\#28326](https://github.com/facebook/react/pull/28326) by [@gaearon](https://github.com/gaearon))  415* Remove `defaultProps` support, except for classes ([\#28733](https://github.com/facebook/react/pull/28733) by [@acdlite](https://github.com/acdlite))  416* Remove UMD builds ([\#28735](https://github.com/facebook/react/pull/28735) by [@gnoff](https://github.com/gnoff))  417* Remove delay for non-transition updates ([\#26597](https://github.com/facebook/react/pull/26597) by [@acdlite](https://github.com/acdlite))  418* Remove `createFactory` ([\#27798](https://github.com/facebook/react/pull/27798) by [@kassens](https://github.com/kassens))419420#### React DOM421422* Adds Form Actions to handle form submission ([\#26379](https://github.com/facebook/react/pull/26379), [\#26674](https://github.com/facebook/react/pull/26674), [\#26689](https://github.com/facebook/react/pull/26689), [\#26708](https://github.com/facebook/react/pull/26708), [\#26714](https://github.com/facebook/react/pull/26714),  [\#26735](https://github.com/facebook/react/pull/26735), [\#26846](https://github.com/facebook/react/pull/26846), [\#27358](https://github.com/facebook/react/pull/27358),  [\#28056](https://github.com/facebook/react/pull/28056) by [@sebmarkbage](https://github.com/sebmarkbage), [@acdlite](https://github.com/acdlite), and [@jupapios](https://github.com/jupapios))  423* Add `useFormStatus()` hook to provide status information of the last form submission ([\#26719](https://github.com/facebook/react/pull/26719), [\#26722](https://github.com/facebook/react/pull/26722), [\#26788](https://github.com/facebook/react/pull/26788),  [\#29019](https://github.com/facebook/react/pull/29019), [\#28728](https://github.com/facebook/react/pull/28728), [\#28413](https://github.com/facebook/react/pull/28413) by [@acdlite](https://github.com/acdlite) and [@eps1lon](https://github.com/eps1lon))  424* Support for Document Metadata. Adds `preinit`, `preinitModule`, `preconnect`, `prefetchDNS`, `preload`, and `preloadModule` APIs.  425  * [\#25060](https://github.com/facebook/react/pull/25060), [\#25243](https://github.com/facebook/react/pull/25243), [\#25388](https://github.com/facebook/react/pull/25388), [\#25432](https://github.com/facebook/react/pull/25432), [\#25436](https://github.com/facebook/react/pull/25436), [\#25426](https://github.com/facebook/react/pull/25426), [\#25500](https://github.com/facebook/react/pull/25500), [\#25480](https://github.com/facebook/react/pull/25480), [\#25508](https://github.com/facebook/react/pull/25508), [\#25515](https://github.com/facebook/react/pull/25515), [\#25514](https://github.com/facebook/react/pull/25514), [\#25532](https://github.com/facebook/react/pull/25532), [\#25536](https://github.com/facebook/react/pull/25536), [\#25534](https://github.com/facebook/react/pull/25534), [\#25546](https://github.com/facebook/react/pull/25546), [\#25559](https://github.com/facebook/react/pull/25559), [\#25569](https://github.com/facebook/react/pull/25569), [\#25599](https://github.com/facebook/react/pull/25599), [\#25689](https://github.com/facebook/react/pull/25689), [\#26106](https://github.com/facebook/react/pull/26106), [\#26152](https://github.com/facebook/react/pull/26152), [\#26239](https://github.com/facebook/react/pull/26239), [\#26237](https://github.com/facebook/react/pull/26237), [\#26280](https://github.com/facebook/react/pull/26280), [\#26154](https://github.com/facebook/react/pull/26154), [\#26256](https://github.com/facebook/react/pull/26256), [\#26353](https://github.com/facebook/react/pull/26353), [\#26427](https://github.com/facebook/react/pull/26427), [\#26450](https://github.com/facebook/react/pull/26450), [\#26502](https://github.com/facebook/react/pull/26502),  [\#26514](https://github.com/facebook/react/pull/26514), [\#26531](https://github.com/facebook/react/pull/26531), [\#26532](https://github.com/facebook/react/pull/26532), [\#26557](https://github.com/facebook/react/pull/26557), [\#26871](https://github.com/facebook/react/pull/26871), [\#26881](https://github.com/facebook/react/pull/26881), [\#26877](https://github.com/facebook/react/pull/26877), [\#26873](https://github.com/facebook/react/pull/26873), [\#26880](https://github.com/facebook/react/pull/26880), [\#26942](https://github.com/facebook/react/pull/26942), [\#26938](https://github.com/facebook/react/pull/26938), [\#26940](https://github.com/facebook/react/pull/26940), [\#26939](https://github.com/facebook/react/pull/26939), [\#27030](https://github.com/facebook/react/pull/27030), [\#27201](https://github.com/facebook/react/pull/27201), [\#27212](https://github.com/facebook/react/pull/27212), [\#27217](https://github.com/facebook/react/pull/27217), [\#27218](https://github.com/facebook/react/pull/27218), [\#27220](https://github.com/facebook/react/pull/27220), [\#27224](https://github.com/facebook/react/pull/27224), [\#27223](https://github.com/facebook/react/pull/27223), [\#27269](https://github.com/facebook/react/pull/27269), [\#27260](https://github.com/facebook/react/pull/27260), [\#27347](https://github.com/facebook/react/pull/27347), [\#27346](https://github.com/facebook/react/pull/27346), [\#27361](https://github.com/facebook/react/pull/27361), [\#27400](https://github.com/facebook/react/pull/27400), [\#27541](https://github.com/facebook/react/pull/27541), [\#27610](https://github.com/facebook/react/pull/27610), [\#28110](https://github.com/facebook/react/pull/28110), [\#29693](https://github.com/facebook/react/pull/29693), [\#29732](https://github.com/facebook/react/pull/29732), [\#29811](https://github.com/facebook/react/pull/29811), [\#27586](https://github.com/facebook/react/pull/27586), [\#28069](https://github.com/facebook/react/pull/28069) by [@gnoff](https://github.com/gnoff), [@sebmarkbage](https://github.com/sebmarkbage), [@acdlite](https://github.com/acdlite), [@kassens](https://github.com/kassens), [@sokra](https://github.com/sokra), [@sweetliquid](https://github.com/sweetliquid)  426* Add `fetchPriority` to `<img>` and `<link>` ([\#25927](https://github.com/facebook/react/pull/25927) by [@styfle](https://github.com/styfle))  427* Add support for SVG `transformOrigin` prop ([\#26130](https://github.com/facebook/react/pull/26130) by [@arav-ind](https://github.com/arav-ind))  428* Add support for `onScrollEnd` event ([\#26789](https://github.com/facebook/react/pull/26789) by [@devongovett](https://github.com/devongovett))  429* Allow `<hr>` as child of `<select>` ([\#27632](https://github.com/facebook/react/pull/27632) by [@SouSingh](https://github.com/SouSingh))  430* Add support for Popover API ([\#27981](https://github.com/facebook/react/pull/27981) by [@eps1lon](https://github.com/eps1lon))  431* Add support for `inert` ([\#24730](https://github.com/facebook/react/pull/24730) by [@eps1lon](https://github.com/eps1lon))  432* Add support for `imageSizes` and `imageSrcSet` ([\#22550](https://github.com/facebook/react/pull/22550) by [@eps1lon](https://github.com/eps1lon))  433* Synchronously flush transitions in popstate events ([\#26025](https://github.com/facebook/react/pull/26025), [\#27559](https://github.com/facebook/react/pull/27559), [\#27505](https://github.com/facebook/react/pull/27505), [\#30759](https://github.com/facebook/react/pull/30759) by [@tyao1](https://github.com/tyao1) and [@acdlite](https://github.com/acdlite))  434* `flushSync` exhausts queue even if something throws ([\#26366](https://github.com/facebook/react/pull/26366) by [@acdlite](https://github.com/acdlite))  435* Throw error if `react` and `react-dom` versions don’t match ([\#29236](https://github.com/facebook/react/pull/29236) by [@acdlite](https://github.com/acdlite))  436* Ensure `srcset` and `src` are assigned last on `<img>` instances ([\#30340](https://github.com/facebook/react/pull/30340) by [@gnoff](https://github.com/gnoff))  437* Javascript URLs are replaced with functions that throw errors ([\#26507](https://github.com/facebook/react/pull/26507), [\#29808](https://github.com/facebook/react/pull/29808) by [@sebmarkbage](https://github.com/sebmarkbage) and [@kassens](https://github.com/kassens))  438* Treat toggle and beforetoggle as discrete events ([\#29176](https://github.com/facebook/react/pull/29176) by [@eps1lon](https://github.com/eps1lon))  439* Filter out empty `src` and `href` attributes (unless for `<a href=”” />`) ([\#18513](https://github.com/facebook/react/pull/18513), [\#28124](https://github.com/facebook/react/pull/28124) by [@bvaughn](https://github.com/bvaughn) and [@eps1lon](https://github.com/eps1lon))  440* Fix unitless `scale` style property ([\#25601](https://github.com/facebook/react/pull/25601) by [@JonnyBurger](https://github.com/JonnyBurger))  441* Fix `onChange` error message for controlled `<select>` ([\#27740](https://github.com/facebook/react/pull/27740) by [@Biki-das](https://github.com/Biki-das))  442* Fix focus restore in child windows after element reorder ([\#30951](https://github.com/facebook/react/pull/30951) by [@ling1726](https://github.com/ling1726))  443* Remove `render`, `hydrate`, `findDOMNode`, `unmountComponentAtNode`, `unstable_createEventHandle`, `unstable_renderSubtreeIntoContainer`, and `unstable_runWithPriority`. Move `createRoot` and `hydrateRoot` to `react-dom/client`. ([\#28271](https://github.com/facebook/react/pull/28271) by [@gnoff](https://github.com/gnoff))  444* Remove `test-utils` ([\#28541](https://github.com/facebook/react/pull/28541) by [@eps1lon](https://github.com/eps1lon))  445* Remove `unstable_flushControlled` ([\#26397](https://github.com/facebook/react/pull/26397) by [@kassens](https://github.com/kassens))  446* Remove legacy mode ([\#28468](https://github.com/facebook/react/pull/28468) by [@gnoff](https://github.com/gnoff))  447* Remove `renderToStaticNodeStream()` ([\#28873](https://github.com/facebook/react/pull/28873) by @gnoff)  448* Remove `unstable_renderSubtreeIntoContainer` ([\#29771](https://github.com/facebook/react/pull/29771) by [@kassens](https://github.com/kassens))449450#### React DOM Server451452* Stable release of React Server Components ([Many, many PRs](https://github.com/facebook/react/pulls?q=is%3Apr+is%3Aclosed+%5BFlight%5D+in%3Atitle+created%3A%3C2024-12-01+) by [@sebmarkbage](https://github.com/sebmarkbage), [@acdlite](https://github.com/acdlite), [@gnoff](https://github.com/gnoff), [@sammy-SC](https://github.com/sammy-SC), [@gaearon](https://github.com/gaearon), [@sophiebits](https://github.com/sophiebits), [@unstubbable](https://github.com/unstubbable), [@lubieowoce](https://github.com/lubieowoce))453* Support Server Actions ([\#26124](https://github.com/facebook/react/pull/26124), [\#26632](https://github.com/facebook/react/pull/26632), [\#27459](https://github.com/facebook/react/pull/27459) by [@sebmarkbage](https://github.com/sebmarkbage) and [@acdlite](https://github.com/acdlite))  454* Changes to SSR  455  * Add external runtime which bootstraps hydration on the client for binary transparency ([\#25437](https://github.com/facebook/react/pull/25437), [\#26169](https://github.com/facebook/react/pull/26169), [\#25499](https://github.com/facebook/react/pull/25499) by [@MofeiZ](https://github.com/mofeiZ) and [@acdlite](https://github.com/acdlite))  456  * Support subresource integrity for `bootstrapScripts` and `bootstrapModules` ([\#25104](https://github.com/facebook/react/pull/25104) by [@gnoff](https://github.com/gnoff))  457  * Fix null bytes written at text chunk boundaries ([\#26228](https://github.com/facebook/react/pull/26228) by [@sophiebits](https://github.com/sophiebits))  458  * Fix logic around attribute serialization ([\#26526](https://github.com/facebook/react/pull/26526) by [@gnoff](https://github.com/gnoff))  459  * Fix precomputed chunk cleared on Node 18 ([\#25645](https://github.com/facebook/react/pull/25645) by [@feedthejim](https://github.com/feedthejim))  460  * Optimize end tag chunks ([\#27522](https://github.com/facebook/react/pull/27522) by [@yujunjung](https://github.com/yujunjung))  461  * Gracefully handle suspending in DOM configs ([\#26768](https://github.com/facebook/react/pull/26768) by [@sebmarkbage](https://github.com/sebmarkbage))  462  * Check for nullish values on ReactCustomFormAction ([\#26770](https://github.com/facebook/react/pull/26770) by [@sebmarkbage](https://github.com/sebmarkbage))  463  * Preload `bootstrapModules`, `bootstrapScripts`, and update priority queue ([\#26754](https://github.com/facebook/react/pull/26754), [\#26753](https://github.com/facebook/react/pull/26753), [\#27190](https://github.com/facebook/react/pull/27190), [\#27189](https://github.com/facebook/react/pull/27189) by [@gnoff](https://github.com/gnoff))  464  * Client render the nearest child or parent suspense boundary if replay errors or is aborted ([\#27386](https://github.com/facebook/react/pull/27386) by [@sebmarkbage](https://github.com/sebmarkbage))  465  * Don't bail out of flushing if we still have pending root tasks ([\#27385](https://github.com/facebook/react/pull/27385) by [@sebmarkbage](https://github.com/sebmarkbage))  466  * Ensure Resumable State is Serializable ([\#27388](https://github.com/facebook/react/pull/27388) by [@sebmarkbage](https://github.com/sebmarkbage))  467  * Remove extra render pass when reverting to client render ([\#26445](https://github.com/facebook/react/pull/26445) by [@acdlite](https://github.com/acdlite))  468  * Fix unwinding context during selective hydration ([\#25876](https://github.com/facebook/react/pull/25876) by [@tyao1](https://github.com/tyao1))  469  * Stop flowing and then abort if a stream is cancelled ([\#27405](https://github.com/facebook/react/pull/27405) by [@sebmarkbage](https://github.com/sebmarkbage))  470  * Pass cancellation reason to abort ([\#27536](https://github.com/facebook/react/pull/27536) by [@sebmarkbage](https://github.com/sebmarkbage))  471  * Add `onHeaders` entrypoint option ([\#27641](https://github.com/facebook/react/pull/27641), [\#27712](https://github.com/facebook/react/pull/27712) by [@gnoff](https://github.com/gnoff))  472  * Escape `<style>` and `<script>` textContent to enable rendering inner content without dangerouslySetInnerHTML ([\#28870](https://github.com/facebook/react/pull/28870), [\#28871](https://github.com/facebook/react/pull/28871) by [@gnoff](https://github.com/gnoff))  473  * Fallback to client replaying actions for Blob serialization ([\#28987](https://github.com/facebook/react/pull/28987) by [@sebmarkbage](https://github.com/sebmarkbage))  474  * Render Suspense fallback if boundary contains new stylesheet during sync update ([\#28965](https://github.com/facebook/react/pull/28965) by [@gnoff](https://github.com/gnoff))  475  * Fix header length tracking (\#30327 by [@gnoff](https://github.com/gnoff))  476  * Use `srcset` to trigger load event on mount (\#30351 by [@gnoff](https://github.com/gnoff))  477  * Don't perform work when closing stream (\#30497 by [@gnoff](https://github.com/gnoff))  478  * Allow aborting during render (\#30488, [\#30730](https://github.com/facebook/react/pull/30730) by [@gnoff](https://github.com/gnoff))  479  * Start initial work immediately (\#31079 by [@gnoff](https://github.com/gnoff))  480  * A transition flowing into a dehydrated boundary no longer suspends when showing fallback ([\#27230](https://github.com/facebook/react/pull/27230) by [@acdlite](https://github.com/acdlite))  481  * Fix selective hydration triggers false update loop error ([\#27439](https://github.com/facebook/react/pull/27439) by [@acdlite](https://github.com/acdlite))  482  * Warn for Child Iterator of all types but allow Generator Components ([\#28853](https://github.com/facebook/react/pull/28853) by [@sebmarkbage](https://github.com/sebmarkbage))  483  * Include regular stack trace in serialized errors ([\#28684](https://github.com/facebook/react/pull/28684), [\#28738](https://github.com/facebook/react/pull/28738) by [@sebmarkbage](https://github.com/sebmarkbage))  484  * Aborting early no longer infinitely suspends ([\#24751](https://github.com/facebook/react/pull/24751) by [@sebmarkbage](https://github.com/sebmarkbage))  485  * Fix hydration warning suppression in text comparisons ([\#24784](https://github.com/facebook/react/pull/24784) by [@gnoff](https://github.com/gnoff))  486  * Changes to error handling in SSR487    * Add diffs to hydration warnings ([\#28502](https://github.com/facebook/react/pull/28502), [\#28512](https://github.com/facebook/react/pull/28512) by [@sebmarkbage](https://github.com/sebmarkbage))  488    * Make Error creation lazy ([\#24728](https://github.com/facebook/react/pull/24728) by [@sebmarkbage](https://github.com/sebmarkbage))  489    * Remove recoverable error when a sync update flows into a dehydrated boundary ([\#25692](https://github.com/facebook/react/pull/25692) by [@sebmarkbage](https://github.com/sebmarkbage))  490    * Don't "fix up" mismatched text content with suppressedHydrationWarning ([\#26391](https://github.com/facebook/react/pull/26391) by [@sebmarkbage](https://github.com/sebmarkbage))  491    * Fix component stacks in errors ([\#27456](https://github.com/facebook/react/pull/27456) by [@sebmarkbage](https://github.com/sebmarkbage))  492    * Add component stacks to `onError` ([\#27761](https://github.com/facebook/react/pull/27761), [\#27850](https://github.com/facebook/react/pull/27850) by [@gnoff](https://github.com/gnoff) and [@sebmarkbage](https://github.com/sebmarkbage))  493    * Throw hydration mismatch errors once ([\#28502](https://github.com/facebook/react/pull/28502) by [@sebmarkbage](https://github.com/sebmarkbage))  494* Add Bun streaming server renderer ([\#25597](https://github.com/facebook/react/pull/25597) by [@colinhacks](https://github.com/colinhacks))  495* Add nonce support to bootstrap scripts ([\#26738](https://github.com/facebook/react/pull/26738) by [@danieltott](https://github.com/danieltott))  496* Add `crossorigin` support to bootstrap scripts ([\#26844](https://github.com/facebook/react/pull/26844) by [@HenriqueLimas](https://github.com/HenriqueLimas))  497* Support `nonce` and `fetchpriority` in preload links ([\#26826](https://github.com/facebook/react/pull/26826) by [@liuyenwei](https://github.com/liuyenwei))  498* Add `referrerPolicy` to `ReactDOM.preload()` ([\#27096](https://github.com/facebook/react/pull/27096) by [@styfle](https://github.com/styfle))  499* Add server condition for `react/jsx-dev-runtime` ([\#28921](https://github.com/facebook/react/pull/28921) by [@himself65](https://github.com/himself65))   500* Export version ([\#29596](https://github.com/facebook/react/pull/29596) by [@unstubbable](https://github.com/unstubbable))  501* Rename the secret export of Client and Server internals ([\#28786](https://github.com/facebook/react/pull/28786), [\#28789](https://github.com/facebook/react/pull/28789) by [@sebmarkbage](https://github.com/sebmarkbage))  502* Remove layout effect warning on server ([\#26395](https://github.com/facebook/react/pull/26395) by [@rickhanlonii](https://github.com/rickhanlonii))  503* Remove `errorInfo.digest` from `onRecoverableError` ([\#28222](https://github.com/facebook/react/pull/28222) by [@gnoff](https://github.com/gnoff))504505#### ReactTestRenderer506507* Add deprecation error to `react-test-renderer` on web ([\#27903](https://github.com/facebook/react/pull/27903), [\#28904](https://github.com/facebook/react/pull/28904) by [@jackpope](https://github.com/jackpope) and [@acdlite](https://github.com/acdlite))  508* Render with ConcurrentRoot on web ([\#28498](https://github.com/facebook/react/pull/28498) by [@jackpope](https://github.com/jackpope))  509* Remove `react-test-renderer/shallow` export ([\#25475](https://github.com/facebook/react/pull/25475), [\#28497](https://github.com/facebook/react/pull/28497) by [@sebmarkbage](https://github.com/sebmarkbage) and [@jackpope](https://github.com/jackpope))510511#### React Reconciler512513* Enable suspending commits without blocking render ([\#26398](https://github.com/facebook/react/pull/26398), [\#26427](https://github.com/facebook/react/pull/26427) by [@acdlite](https://github.com/acdlite))  514* Remove `prepareUpdate` ([\#26583](https://github.com/facebook/react/pull/26583), [\#27409](http://github.com/facebook/react/pull/27409) by [@sebmarkbage](https://github.com/sebmarkbage) and [@sophiebits](https://github.com/sophiebits))515516#### React-Is517518* Enable tree shaking ([\#27701](https://github.com/facebook/react/pull/27701) by [@markerikson](https://github.com/markerikson))  519* Remove `isConcurrentMode` and `isAsyncMode` methods ([\#28224](https://github.com/facebook/react/pull/28224) by @gaearon)520521#### useSyncExternalStore522523* Remove React internals access ([\#29868](https://github.com/facebook/react/pull/29868) by [@phryneas](https://github.com/phryneas))  524* Fix stale selectors keeping previous store references ([\#25969](https://github.com/facebook/react/pull/25968) by [@jellevoost](https://github.com/jellevoost))525526## 18.3.1 (April 26, 2024)527528- Export `act` from `react` [f1338f](https://github.com/facebook/react/commit/f1338f8080abd1386454a10bbf93d67bfe37ce85)529530## 18.3.0 (April 25, 2024)531532This release is identical to 18.2 but adds warnings for deprecated APIs and other changes that are needed for React 19.533534Read the [React 19 Upgrade Guide](https://react.dev/blog/2024/04/25/react-19-upgrade-guide) for more info.535536### React537538- Allow writing to `this.refs` to support string ref codemod [909071](https://github.com/facebook/react/commit/9090712fd3ca4e1099e1f92e67933c2cb4f32552)539- Warn for deprecated `findDOMNode` outside StrictMode [c3b283](https://github.com/facebook/react/commit/c3b283964108b0e8dbcf1f9eb2e7e67815e39dfb)540- Warn for deprecated `test-utils` methods [d4ea75](https://github.com/facebook/react/commit/d4ea75dc4258095593b6ac764289f42bddeb835c)541- Warn for deprecated Legacy Context outside StrictMode [415ee0](https://github.com/facebook/react/commit/415ee0e6ea0fe3e288e65868df2e3241143d5f7f)542- Warn for deprecated string refs outside StrictMode [#25383](https://github.com/facebook/react/pull/25383)543- Warn for deprecated `defaultProps` for function components [#25699](https://github.com/facebook/react/pull/25699)544- Warn when spreading `key` [#25697](https://github.com/facebook/react/pull/25697)545- Warn when using `act` from `test-utils` [d4ea75](https://github.com/facebook/react/commit/d4ea75dc4258095593b6ac764289f42bddeb835c)546547### React DOM548- Warn for deprecated `unmountComponentAtNode` [8a015b](https://github.com/facebook/react/commit/8a015b68cc060079878e426610e64e86fb328f8d)549- Warn for deprecated `renderToStaticNodeStream` [#28874](https://github.com/facebook/react/pull/28874)550551## 18.2.0 (June 14, 2022)552553### React DOM554555* Provide a component stack as a second argument to `onRecoverableError`. ([@gnoff](https://github.com/gnoff) in [#24591](https://github.com/facebook/react/pull/24591))556* Fix hydrating into `document` causing a blank page on mismatch. ([@gnoff](https://github.com/gnoff) in [#24523](https://github.com/facebook/react/pull/24523))557* Fix false positive hydration errors with Suspense. ([@gnoff](https://github.com/gnoff) in [#24480](https://github.com/facebook/react/pull/24480) and  [@acdlite](https://github.com/acdlite) in [#24532](https://github.com/facebook/react/pull/24532))558* Fix ignored `setState` in Safari when adding an iframe. ([@gaearon](https://github.com/gaearon) in [#24459](https://github.com/facebook/react/pull/24459))559560### React DOM Server561562* Pass information about server errors to the client. ([@salazarm](https://github.com/salazarm) and [@gnoff](https://github.com/gnoff) in [#24551](https://github.com/facebook/react/pull/24551) and [#24591](https://github.com/facebook/react/pull/24591))563* Allow to provide a reason when aborting the HTML stream. ([@gnoff](https://github.com/gnoff) in [#24680](https://github.com/facebook/react/pull/24680))564* Eliminate extraneous text separators in the HTML where possible. ([@gnoff](https://github.com/gnoff) in [#24630](https://github.com/facebook/react/pull/24630))565* Disallow complex children inside `<title>` elements to match the browser constraints. ([@gnoff](https://github.com/gnoff) in [#24679](https://github.com/facebook/react/pull/24679))566* Fix buffering in some worker environments by explicitly setting `highWaterMark` to `0`. ([@jplhomer](https://github.com/jplhomer) in [#24641](https://github.com/facebook/react/pull/24641))567568### Server Components (Experimental)569570* Add support for `useId()` inside Server Components. ([@gnoff](https://github.com/gnoff) in [#24172](https://github.com/facebook/react/pull/24172))571572## 18.1.0 (April 26, 2022)573574### React DOM575576* Fix the false positive warning about `react-dom/client` when using UMD bundle. ([@alireza-molaee](https://github.com/alireza-molaee) in [#24274](https://github.com/facebook/react/pull/24274))577* Fix `suppressHydrationWarning` to work in production too. ([@gaearon](https://github.com/gaearon) in [#24271](https://github.com/facebook/react/pull/24271))578* Fix `componentWillUnmount` firing twice inside of Suspense. ([@acdlite](https://github.com/acdlite) in [#24308](https://github.com/facebook/react/pull/24308))579* Fix some transition updates being ignored. ([@acdlite](https://github.com/acdlite) in [#24353](https://github.com/facebook/react/pull/24353))580* Fix `useDeferredValue` causing an infinite loop when passed an unmemoized value. ([@acdlite](https://github.com/acdlite) in [#24247](https://github.com/facebook/react/pull/24247))581* Fix throttling of revealing Suspense fallbacks. ([@sunderls](https://github.com/sunderls) in [#24253](https://github.com/facebook/react/pull/24253))582* Fix an inconsistency in whether the props object is the same between renders. ([@Andarist](https://github.com/Andarist) and [@acdlite](https://github.com/acdlite) in [#24421](https://github.com/facebook/react/pull/24421))583* Fix a missing warning about a `setState` loop in `useEffect`. ([@gaearon](https://github.com/gaearon) in [#24298](https://github.com/facebook/react/pull/24298))584* Fix a spurious hydration error. ([@gnoff](https://github.com/gnoff) in [#24404](https://github.com/facebook/react/pull/24404))585* Warn when calling `setState` in `useInsertionEffect`. ([@gaearon](https://github.com/gaearon) in [#24295](https://github.com/facebook/react/pull/24295))586* Ensure the reason for hydration errors is always displayed. ([@gaearon](https://github.com/gaearon) in [#24276](https://github.com/facebook/react/pull/24276))587588### React DOM Server589590* Fix escaping for the `bootstrapScriptContent` contents. ([@gnoff](https://github.com/gnoff) in [#24385](https://github.com/facebook/react/pull/24385))591* Significantly improve performance of `renderToPipeableStream`. ([@gnoff](https://github.com/gnoff) in [#24291](https://github.com/facebook/react/pull/24291))592593### ESLint Plugin: React Hooks594595* Fix false positive errors with a large number of branches. ([@scyron6](https://github.com/scyron6) in [#24287](https://github.com/facebook/react/pull/24287))596* Don't consider a known dependency stable when the variable is reassigned. ([@afzalsayed96](https://github.com/afzalsayed96) in [#24343](https://github.com/facebook/react/pull/24343))597598### Use Subscription599600* Replace the implementation with the `use-sync-external-store` shim. ([@gaearon](https://github.com/gaearon) in [#24289](https://github.com/facebook/react/pull/24289))601602## 18.0.0 (March 29, 2022)603604Below is a list of all new features, APIs, deprecations, and breaking changes.605Read [React 18 release post](https://reactjs.org/blog/2022/03/29/react-v18.html) and [React 18 upgrade guide](https://reactjs.org/blog/2022/03/08/react-18-upgrade-guide.html) for more information.606607### New Features608609### React610611* `useId` is a new hook for generating unique IDs on both the client and server, while avoiding hydration mismatches. It is primarily useful for component libraries integrating with accessibility APIs that require unique IDs. This solves an issue that already exists in React 17 and below, but it’s even more important in React 18 because of how the new streaming server renderer delivers HTML out-of-order.612* `startTransition` and `useTransition` let you mark some state updates as not urgent. Other state updates are considered urgent by default. React will allow urgent state updates (for example, updating a text input) to interrupt non-urgent state updates (for example, rendering a list of search results).613* `useDeferredValue` lets you defer re-rendering a non-urgent part of the tree. It is similar to debouncing, but has a few advantages compared to it. There is no fixed time delay, so React will attempt the deferred render right after the first render is reflected on the screen. The deferred render is interruptible and doesn't block user input.614* `useSyncExternalStore` is a new hook that allows external stores to support concurrent reads by forcing updates to the store to be synchronous. It removes the need for `useEffect` when implementing subscriptions to external data sources, and is recommended for any library that integrates with state external to React.615* `useInsertionEffect` is a new hook that allows CSS-in-JS libraries to address performance issues of injecting styles in render. Unless you’ve already built a CSS-in-JS library we don’t expect you to ever use this. This hook will run after the DOM is mutated, but before layout effects read the new layout. This solves an issue that already exists in React 17 and below, but is even more important in React 18 because React yields to the browser during concurrent rendering, giving it a chance to recalculate layout.616617### React DOM Client618619These new APIs are now exported from `react-dom/client`:620621* `createRoot`: New method to create a root to `render` or `unmount`. Use it instead of `ReactDOM.render`. New features in React 18 don't work without it.622* `hydrateRoot`: New method to hydrate a server rendered application. Use it instead of `ReactDOM.hydrate` in conjunction with the new React DOM Server APIs. New features in React 18 don't work without it.623624Both `createRoot` and `hydrateRoot` accept a new option called `onRecoverableError` in case you want to be notified when React recovers from errors during rendering or hydration for logging. By default, React will use [`reportError`](https://developer.mozilla.org/en-US/docs/Web/API/reportError), or `console.error` in the older browsers.625626### React DOM Server627628These new APIs are now exported from `react-dom/server` and have full support for streaming Suspense on the server:629630* `renderToPipeableStream`: for streaming in Node environments.631* `renderToReadableStream`: for modern edge runtime environments, such as Deno and Cloudflare workers.632633The existing `renderToString` method keeps working but is discouraged.634635## Deprecations636637* `react-dom`: `ReactDOM.render` has been deprecated. Using it will warn and run your app in React 17 mode.638* `react-dom`: `ReactDOM.hydrate` has been deprecated. Using it will warn and run your app in React 17 mode.639* `react-dom`: `ReactDOM.unmountComponentAtNode` has been deprecated.640* `react-dom`: `ReactDOM.renderSubtreeIntoContainer` has been deprecated.641* `react-dom/server`: `ReactDOMServer.renderToNodeStream` has been deprecated.642643## Breaking Changes644645### React646647* **Automatic batching:** This release introduces a performance improvement that changes to the way React batches updates to do more batching automatically. See [Automatic batching for fewer renders in React 18](https://github.com/reactwg/react-18/discussions/21) for more info. In the rare case that you need to opt out, wrap the state update in `flushSync`.648* **Stricter Strict Mode**: In the future, React will provide a feature that lets components preserve state between unmounts. To prepare for it, React 18 introduces a new development-only check to Strict Mode. React will automatically unmount and remount every component, whenever a component mounts for the first time, restoring the previous state on the second mount. If this breaks your app, consider removing Strict Mode until you can fix the components to be resilient to remounting with existing state.649* **Consistent useEffect timing**: React now always synchronously flushes effect functions if the update was triggered during a discrete user input event such as a click or a keydown event. Previously, the behavior wasn't always predictable or consistent.650* **Stricter hydration errors**: Hydration mismatches due to missing or extra text content are now treated like errors instead of warnings. React will no longer attempt to "patch up" individual nodes by inserting or deleting a node on the client in an attempt to match the server markup, and will revert to client rendering up to the closest `<Suspense>` boundary in the tree. This ensures the hydrated tree is consistent and avoids potential privacy and security holes that can be caused by hydration mismatches.651* **Suspense trees are always consistent:** If a component suspends before it's fully added to the tree, React will not add it to the tree in an incomplete state or fire its effects. Instead, React will throw away the new tree completely, wait for the asynchronous operation to finish, and then retry rendering again from scratch. React will render the retry attempt concurrently, and without blocking the browser.652* **Layout Effects with Suspense**: When a tree re-suspends and reverts to a fallback, React will now clean up layout effects, and then re-create them when the content inside the boundary is shown again. This fixes an issue which prevented component libraries from correctly measuring layout when used with Suspense.653* **New JS Environment Requirements**: React now depends on modern browsers features including `Promise`, `Symbol`, and `Object.assign`. If you support older browsers and devices such as Internet Explorer which do not provide modern browser features natively or have non-compliant implementations, consider including a global polyfill in your bundled application.654655### Scheduler (Experimental)656657* Remove unstable `scheduler/tracing` API658659## Notable Changes660661### React662663* **Components can now render `undefined`:** React no longer throws if you return `undefined` from a component. This makes the allowed component return values consistent with values that are allowed in the middle of a component tree. We suggest to use a linter to prevent mistakes like forgetting a `return` statement before JSX.664* **In tests, `act` warnings are now opt-in:** If you're running end-to-end tests, the `act` warnings are unnecessary. We've introduced an [opt-in](https://github.com/reactwg/react-18/discussions/102) mechanism so you can enable them only for unit tests where they are useful and beneficial.665* **No warning about `setState` on unmounted components:** Previously, React warned about memory leaks when you call `setState` on an unmounted component. This warning was added for subscriptions, but people primarily run into it in scenarios where setting state is fine, and workarounds make the code worse. We've [removed](https://github.com/facebook/react/pull/22114) this warning.666* **No suppression of console logs:** When you use Strict Mode, React renders each component twice to help you find unexpected side effects. In React 17, we've suppressed console logs for one of the two renders to make the logs easier to read. In response to [community feedback](https://github.com/facebook/react/issues/21783) about this being confusing, we've removed the suppression. Instead, if you have React DevTools installed, the second log's renders will be displayed in grey, and there will be an option (off by default) to suppress them completely.667* **Improved memory usage:** React now cleans up more internal fields on unmount, making the impact from unfixed memory leaks that may exist in your application code less severe.668669### React DOM Server670671* **`renderToString`:** Will no longer error when suspending on the server. Instead, it will emit the fallback HTML for the closest `<Suspense>` boundary and then retry rendering the same content on the client. It is still recommended that you switch to a streaming API like `renderToPipeableStream` or `renderToReadableStream` instead.672* **`renderToStaticMarkup`:** Will no longer error when suspending on the server. Instead, it will emit the fallback HTML for the closest `<Suspense>` boundary and retry rendering on the client.673674## All Changes675676## React677678* Add `useTransition` and `useDeferredValue` to separate urgent updates from transitions. ([#10426](https://github.com/facebook/react/pull/10426), [#10715](https://github.com/facebook/react/pull/10715), [#15593](https://github.com/facebook/react/pull/15593), [#15272](https://github.com/facebook/react/pull/15272), [#15578](https://github.com/facebook/react/pull/15578), [#15769](https://github.com/facebook/react/pull/15769), [#17058](https://github.com/facebook/react/pull/17058), [#18796](https://github.com/facebook/react/pull/18796), [#19121](https://github.com/facebook/react/pull/19121), [#19703](https://github.com/facebook/react/pull/19703), [#19719](https://github.com/facebook/react/pull/19719), [#19724](https://github.com/facebook/react/pull/19724), [#20672](https://github.com/facebook/react/pull/20672), [#20976](https://github.com/facebook/react/pull/20976) by [@acdlite](https://github.com/acdlite), [@lunaruan](https://github.com/lunaruan), [@rickhanlonii](https://github.com/rickhanlonii), and [@sebmarkbage](https://github.com/sebmarkbage))679* Add `useId` for generating unique IDs. ([#17322](https://github.com/facebook/react/pull/17322), [#18576](https://github.com/facebook/react/pull/18576), [#22644](https://github.com/facebook/react/pull/22644), [#22672](https://github.com/facebook/react/pull/22672), [#21260](https://github.com/facebook/react/pull/21260) by [@acdlite](https://github.com/acdlite), [@lunaruan](https://github.com/lunaruan), and [@sebmarkbage](https://github.com/sebmarkbage))680* Add `useSyncExternalStore` to help external store libraries integrate with React. ([#15022](https://github.com/facebook/react/pull/15022), [#18000](https://github.com/facebook/react/pull/18000), [#18771](https://github.com/facebook/react/pull/18771), [#22211](https://github.com/facebook/react/pull/22211), [#22292](https://github.com/facebook/react/pull/22292), [#22239](https://github.com/facebook/react/pull/22239), [#22347](https://github.com/facebook/react/pull/22347), [#23150](https://github.com/facebook/react/pull/23150) by [@acdlite](https://github.com/acdlite), [@bvaughn](https://github.com/bvaughn), and [@drarmstr](https://github.com/drarmstr))681* Add `startTransition` as a version of `useTransition` without pending feedback. ([#19696](https://github.com/facebook/react/pull/19696) by [@rickhanlonii](https://github.com/rickhanlonii))682* Add `useInsertionEffect` for CSS-in-JS libraries. ([#21913](https://github.com/facebook/react/pull/21913) by [@rickhanlonii](https://github.com/rickhanlonii))683* Make Suspense remount layout effects when content reappears. ([#19322](https://github.com/facebook/react/pull/19322), [#19374](https://github.com/facebook/react/pull/19374), [#19523](https://github.com/facebook/react/pull/19523), [#20625](https://github.com/facebook/react/pull/20625), [#21079](https://github.com/facebook/react/pull/21079) by [@acdlite](https://github.com/acdlite), [@bvaughn](https://github.com/bvaughn), and [@lunaruan](https://github.com/lunaruan))684* Make `<StrictMode>` re-run effects to check for restorable state. ([#19523](https://github.com/facebook/react/pull/19523) , [#21418](https://github.com/facebook/react/pull/21418) by [@bvaughn](https://github.com/bvaughn) and [@lunaruan](https://github.com/lunaruan))685* Assume Symbols are always available. ([#23348](https://github.com/facebook/react/pull/23348) by [@sebmarkbage](https://github.com/sebmarkbage))686* Remove `object-assign` polyfill. ([#23351](https://github.com/facebook/react/pull/23351) by [@sebmarkbage](https://github.com/sebmarkbage))687* Remove unsupported `unstable_changedBits` API. ([#20953](https://github.com/facebook/react/pull/20953) by [@acdlite](https://github.com/acdlite))688* Allow components to render undefined. ([#21869](https://github.com/facebook/react/pull/21869) by [@rickhanlonii](https://github.com/rickhanlonii))689* Flush `useEffect` resulting from discrete events like clicks synchronously. ([#21150](https://github.com/facebook/react/pull/21150) by [@acdlite](https://github.com/acdlite))690* Suspense `fallback={undefined}` now behaves the same as `null` and isn't ignored. ([#21854](https://github.com/facebook/react/pull/21854) by [@rickhanlonii](https://github.com/rickhanlonii))691* Consider all `lazy()` resolving to the same component equivalent. ([#20357](https://github.com/facebook/react/pull/20357) by [@sebmarkbage](https://github.com/sebmarkbage))692* Don't patch console during first render. ([#22308](https://github.com/facebook/react/pull/22308) by [@lunaruan](https://github.com/lunaruan))693* Improve memory usage. ([#21039](https://github.com/facebook/react/pull/21039) by [@bgirard](https://github.com/bgirard))694* Improve messages if string coercion throws (Temporal.*, Symbol, etc.) ([#22064](https://github.com/facebook/react/pull/22064) by [@justingrant](https://github.com/justingrant))695* Use `setImmediate` when available over `MessageChannel`. ([#20834](https://github.com/facebook/react/pull/20834) by [@gaearon](https://github.com/gaearon))696* Fix context failing to propagate inside suspended trees. ([#23095](https://github.com/facebook/react/pull/23095) by [@gaearon](https://github.com/gaearon))697* Fix `useReducer` observing incorrect props by removing the eager bailout mechanism. ([#22445](https://github.com/facebook/react/pull/22445) by [@josephsavona](https://github.com/josephsavona))698* Fix `setState` being ignored in Safari when appending iframes. ([#23111](https://github.com/facebook/react/pull/23111) by [@gaearon](https://github.com/gaearon))699* Fix a crash when rendering `ZonedDateTime` in the tree. ([#20617](https://github.com/facebook/react/pull/20617) by [@dimaqq](https://github.com/dimaqq))700* Fix a crash when document is set to `null` in tests. ([#22695](https://github.com/facebook/react/pull/22695) by [@SimenB](https://github.com/SimenB))701* Fix `onLoad` not triggering when concurrent features are on. ([#23316](https://github.com/facebook/react/pull/23316) by [@gnoff](https://github.com/gnoff))702* Fix a warning when a selector returns `NaN`.  ([#23333](https://github.com/facebook/react/pull/23333) by [@hachibeeDI](https://github.com/hachibeeDI))703* Fix the generated license header. ([#23004](https://github.com/facebook/react/pull/23004) by [@vitaliemiron](https://github.com/vitaliemiron))704* Add `package.json` as one of the entry points. ([#22954](https://github.com/facebook/react/pull/22954) by [@Jack](https://github.com/Jack-Works))705* Allow suspending outside a Suspense boundary. ([#23267](https://github.com/facebook/react/pull/23267) by [@acdlite](https://github.com/acdlite))706* Log a recoverable error whenever hydration fails. ([#23319](https://github.com/facebook/react/pull/23319) by [@acdlite](https://github.com/acdlite))707708### React DOM709710* Add `createRoot` and `hydrateRoot`. ([#10239](https://github.com/facebook/react/pull/10239), [#11225](https://github.com/facebook/react/pull/11225), [#12117](https://github.com/facebook/react/pull/12117), [#13732](https://github.com/facebook/react/pull/13732), [#15502](https://github.com/facebook/react/pull/15502), [#15532](https://github.com/facebook/react/pull/15532), [#17035](https://github.com/facebook/react/pull/17035), [#17165](https://github.com/facebook/react/pull/17165), [#20669](https://github.com/facebook/react/pull/20669), [#20748](https://github.com/facebook/react/pull/20748), [#20888](https://github.com/facebook/react/pull/20888), [#21072](https://github.com/facebook/react/pull/21072), [#21417](https://github.com/facebook/react/pull/21417), [#21652](https://github.com/facebook/react/pull/21652), [#21687](https://github.com/facebook/react/pull/21687), [#23207](https://github.com/facebook/react/pull/23207), [#23385](https://github.com/facebook/react/pull/23385) by [@acdlite](https://github.com/acdlite), [@bvaughn](https://github.com/bvaughn), [@gaearon](https://github.com/gaearon), [@lunaruan](https://github.com/lunaruan), [@rickhanlonii](https://github.com/rickhanlonii), [@trueadm](https://github.com/trueadm), and [@sebmarkbage](https://github.com/sebmarkbage))711* Add selective hydration. ([#14717](https://github.com/facebook/react/pull/14717), [#14884](https://github.com/facebook/react/pull/14884), [#16725](https://github.com/facebook/react/pull/16725), [#16880](https://github.com/facebook/react/pull/16880), [#17004](https://github.com/facebook/react/pull/17004), [#22416](https://github.com/facebook/react/pull/22416), [#22629](https://github.com/facebook/react/pull/22629), [#22448](https://github.com/facebook/react/pull/22448), [#22856](https://github.com/facebook/react/pull/22856), [#23176](https://github.com/facebook/react/pull/23176) by [@acdlite](https://github.com/acdlite), [@gaearon](https://github.com/gaearon), [@salazarm](https://github.com/salazarm), and [@sebmarkbage](https://github.com/sebmarkbage))712* Add `aria-description` to the list of known ARIA attributes. ([#22142](https://github.com/facebook/react/pull/22142) by [@mahyareb](https://github.com/mahyareb))713* Add `onResize` event to video elements. ([#21973](https://github.com/facebook/react/pull/21973) by [@rileyjshaw](https://github.com/rileyjshaw))714* Add `imageSizes` and `imageSrcSet` to known props. ([#22550](https://github.com/facebook/react/pull/22550) by [@eps1lon](https://github.com/eps1lon))715* Allow non-string `<option>` children if `value` is provided.  ([#21431](https://github.com/facebook/react/pull/21431) by [@sebmarkbage](https://github.com/sebmarkbage))716* Fix `aspectRatio` style not being applied. ([#21100](https://github.com/facebook/react/pull/21100) by [@gaearon](https://github.com/gaearon))717* Warn if `renderSubtreeIntoContainer` is called. ([#23355](https://github.com/facebook/react/pull/23355) by [@acdlite](https://github.com/acdlite))718719### React DOM Server720721* Add the new streaming renderer. ([#14144](https://github.com/facebook/react/pull/14144), [#20970](https://github.com/facebook/react/pull/20970), [#21056](https://github.com/facebook/react/pull/21056), [#21255](https://github.com/facebook/react/pull/21255), [#21200](https://github.com/facebook/react/pull/21200), [#21257](https://github.com/facebook/react/pull/21257), [#21276](https://github.com/facebook/react/pull/21276), [#22443](https://github.com/facebook/react/pull/22443), [#22450](https://github.com/facebook/react/pull/22450), [#23247](https://github.com/facebook/react/pull/23247), [#24025](https://github.com/facebook/react/pull/24025), [#24030](https://github.com/facebook/react/pull/24030) by [@sebmarkbage](https://github.com/sebmarkbage))722* Fix context providers in SSR when handling multiple requests. ([#23171](https://github.com/facebook/react/pull/23171) by [@frandiox](https://github.com/frandiox))723* Revert to client render on text mismatch. ([#23354](https://github.com/facebook/react/pull/23354) by [@acdlite](https://github.com/acdlite))724* Deprecate `renderToNodeStream`. ([#23359](https://github.com/facebook/react/pull/23359) by [@sebmarkbage](https://github.com/sebmarkbage))725* Fix a spurious error log in the new server renderer. ([#24043](https://github.com/facebook/react/pull/24043) by [@eps1lon](https://github.com/eps1lon))726* Fix a bug in the new server renderer. ([#22617](https://github.com/facebook/react/pull/22617) by [@shuding](https://github.com/shuding))727* Ignore function and symbol values inside custom elements on the server. ([#21157](https://github.com/facebook/react/pull/21157) by [@sebmarkbage](https://github.com/sebmarkbage))728729### React DOM Test Utils730731* Throw when `act` is used in production. ([#21686](https://github.com/facebook/react/pull/21686) by [@acdlite](https://github.com/acdlite))732* Support disabling spurious act warnings with `global.IS_REACT_ACT_ENVIRONMENT`. ([#22561](https://github.com/facebook/react/pull/22561) by [@acdlite](https://github.com/acdlite))733* Expand act warning to cover all APIs that might schedule React work. ([#22607](https://github.com/facebook/react/pull/22607) by [@acdlite](https://github.com/acdlite))734* Make `act` batch updates. ([#21797](https://github.com/facebook/react/pull/21797) by [@acdlite](https://github.com/acdlite))735* Remove warning for dangling passive effects. ([#22609](https://github.com/facebook/react/pull/22609) by [@acdlite](https://github.com/acdlite))736737### React Refresh738739* Track late-mounted roots in Fast Refresh. ([#22740](https://github.com/facebook/react/pull/22740) by [@anc95](https://github.com/anc95))740* Add `exports` field to `package.json`. ([#23087](https://github.com/facebook/react/pull/23087) by [@otakustay](https://github.com/otakustay))741742### Server Components (Experimental)743744* Add Server Context support. ([#23244](https://github.com/facebook/react/pull/23244) by [@salazarm](https://github.com/salazarm))745* Add `lazy` support. ([#24068](https://github.com/facebook/react/pull/24068) by [@gnoff](https://github.com/gnoff))746* Update webpack plugin for webpack 5 ([#22739](https://github.com/facebook/react/pull/22739) by [@michenly](https://github.com/michenly))747* Fix a mistake in the Node loader. ([#22537](https://github.com/facebook/react/pull/22537) by [@btea](https://github.com/btea))748* Use `globalThis` instead of `window` for edge environments. ([#22777](https://github.com/facebook/react/pull/22777) by [@huozhi](https://github.com/huozhi))749750### Scheduler (Experimental)751752* Remove unstable `scheduler/tracing` API ([#20037](https://github.com/facebook/react/pull/20037) by [@bvaughn](https://github.com/bvaughn))753754## 17.0.2 (March 22, 2021)755756### React DOM757758* Remove an unused dependency to address the [`SharedArrayBuffer` cross-origin isolation warning](https://developer.chrome.com/blog/enabling-shared-array-buffer/). ([@koba04](https://github.com/koba04) and [@bvaughn](https://github.com/bvaughn) in [#20831](https://github.com/facebook/react/pull/20831), [#20832](https://github.com/facebook/react/pull/20832), and [#20840](https://github.com/facebook/react/pull/20840))759760## 17.0.1 (October 22, 2020)761762### React DOM763764* Fix a crash in IE11. ([@gaearon](https://github.com/gaearon) in [#20071](https://github.com/facebook/react/pull/20071))765766## 17.0.0 (October 20, 2020)767768Today, we are releasing React 17!769770**[Learn more about React 17 and how to update to it on the official React blog.](https://reactjs.org/blog/2020/10/20/react-v17.html)**771772### React773774* Add `react/jsx-runtime` and `react/jsx-dev-runtime` for the [new JSX transform](https://babeljs.io/blog/2020/03/16/7.9.0#a-new-jsx-transform-11154-https-githubcom-babel-babel-pull-11154). ([@lunaruan](https://github.com/lunaruan) in [#18299](https://github.com/facebook/react/pull/18299))775* Build component stacks from native error frames. ([@sebmarkbage](https://github.com/sebmarkbage) in [#18561](https://github.com/facebook/react/pull/18561))776* Allow to specify `displayName` on context for improved stacks. ([@eps1lon](https://github.com/eps1lon) in [#18224](https://github.com/facebook/react/pull/18224))777* Prevent `'use strict'` from leaking in the UMD bundles. ([@koba04](https://github.com/koba04) in [#19614](https://github.com/facebook/react/pull/19614))778* Stop using `fb.me` for redirects. ([@cylim](https://github.com/cylim) in [#19598](https://github.com/facebook/react/pull/19598))779780### React DOM781782* Delegate events to roots instead of `document`. ([@trueadm](https://github.com/trueadm) in [#18195](https://github.com/facebook/react/pull/18195) and [others](https://github.com/facebook/react/pulls?q=is%3Apr+author%3Atrueadm+modern+event+is%3Amerged))783* Clean up all effects before running any next effects. ([@bvaughn](https://github.com/bvaughn) in [#17947](https://github.com/facebook/react/pull/17947))784* Run `useEffect` cleanup functions asynchronously. ([@bvaughn](https://github.com/bvaughn) in [#17925](https://github.com/facebook/react/pull/17925))785* Use browser `focusin` and `focusout` for `onFocus` and `onBlur`. ([@trueadm](https://github.com/trueadm) in [#19186](https://github.com/facebook/react/pull/19186))786* Make all `Capture` events use the browser capture phase. ([@trueadm](https://github.com/trueadm) in [#19221](https://github.com/facebook/react/pull/19221))787* Don't emulate bubbling of the `onScroll` event. ([@gaearon](https://github.com/gaearon) in [#19464](https://github.com/facebook/react/pull/19464))788* Throw if `forwardRef` or `memo` component returns `undefined`. ([@gaearon](https://github.com/gaearon) in [#19550](https://github.com/facebook/react/pull/19550))789* Remove event pooling. ([@trueadm](https://github.com/trueadm) in [#18969](https://github.com/facebook/react/pull/18969))790* Stop exposing internals that won’t be needed by React Native Web. ([@necolas](https://github.com/necolas) in [#18483](https://github.com/facebook/react/pull/18483))791* Attach all known event listeners when the root mounts. ([@gaearon](https://github.com/gaearon) in [#19659](https://github.com/facebook/react/pull/19659))792* Disable `console` in the second render pass of DEV mode double render. ([@sebmarkbage](https://github.com/sebmarkbage) in [#18547](https://github.com/facebook/react/pull/18547))793* Deprecate the undocumented and misleading `ReactTestUtils.SimulateNative` API. ([@gaearon](https://github.com/gaearon) in [#13407](https://github.com/facebook/react/pull/13407))794* Rename private field names used in the internals. ([@gaearon](https://github.com/gaearon) in [#18377](https://github.com/facebook/react/pull/18377))795* Don't call User Timing API in development. ([@gaearon](https://github.com/gaearon) in [#18417](https://github.com/facebook/react/pull/18417))796* Disable console during the repeated render in Strict Mode. ([@sebmarkbage](https://github.com/sebmarkbage) in [#18547](https://github.com/facebook/react/pull/18547))797* In Strict Mode, double-render components without Hooks too. ([@eps1lon](https://github.com/eps1lon) in [#18430](https://github.com/facebook/react/pull/18430))798* Allow calling `ReactDOM.flushSync` during lifecycle methods (but warn). ([@sebmarkbage](https://github.com/sebmarkbage) in [#18759](https://github.com/facebook/react/pull/18759))799* Add the `code` property to the keyboard event objects. ([@bl00mber](https://github.com/bl00mber) in [#18287](https://github.com/facebook/react/pull/18287))800* Add the `disableRemotePlayback` property for `video` elements. ([@tombrowndev](https://github.com/tombrowndev) in [#18619](https://github.com/facebook/react/pull/18619))801* Add the `enterKeyHint` property for `input` elements. ([@eps1lon](https://github.com/eps1lon) in [#18634](https://github.com/facebook/react/pull/18634))802* Warn when no `value` is provided to `<Context.Provider>`. ([@charlie1404](https://github.com/charlie1404) in [#19054](https://github.com/facebook/react/pull/19054))803* Warn when `memo` or `forwardRef` components return `undefined`. ([@bvaughn](https://github.com/bvaughn) in [#19550](https://github.com/facebook/react/pull/19550))804* Improve the error message for invalid updates. ([@JoviDeCroock](https://github.com/JoviDeCroock) in [#18316](https://github.com/facebook/react/pull/18316))805* Exclude forwardRef and memo from stack frames. ([@sebmarkbage](https://github.com/sebmarkbage) in [#18559](https://github.com/facebook/react/pull/18559))806* Improve the error message when switching between controlled and uncontrolled inputs. ([@vcarl](https://github.com/vcarl) in [#17070](https://github.com/facebook/react/pull/17070))807* Keep `onTouchStart`, `onTouchMove`, and `onWheel` passive. ([@gaearon](https://github.com/gaearon) in [#19654](https://github.com/facebook/react/pull/19654))808* Fix `setState` hanging in development inside a closed iframe. ([@gaearon](https://github.com/gaearon) in [#19220](https://github.com/facebook/react/pull/19220))809* Fix rendering bailout for lazy components with `defaultProps`. ([@jddxf](https://github.com/jddxf) in [#18539](https://github.com/facebook/react/pull/18539))810* Fix a false positive warning when `dangerouslySetInnerHTML` is `undefined`. ([@eps1lon](https://github.com/eps1lon) in [#18676](https://github.com/facebook/react/pull/18676))811* Fix Test Utils with non-standard `require` implementation. ([@just-boris](https://github.com/just-boris) in [#18632](https://github.com/facebook/react/pull/18632))812* Fix `onBeforeInput` reporting an incorrect `event.type`. ([@eps1lon](https://github.com/eps1lon) in [#19561](https://github.com/facebook/react/pull/19561))813* Fix `event.relatedTarget` reported as `undefined` in Firefox. ([@claytercek](https://github.com/claytercek) in [#19607](https://github.com/facebook/react/pull/19607))814* Fix "unspecified error" in IE11. ([@hemakshis](https://github.com/hemakshis) in [#19664](https://github.com/facebook/react/pull/19664))815* Fix rendering into a shadow root. ([@Jack-Works](https://github.com/Jack-Works) in [#15894](https://github.com/facebook/react/pull/15894))816* Fix `movementX/Y` polyfill with capture events. ([@gaearon](https://github.com/gaearon) in [#19672](https://github.com/facebook/react/pull/19672))817* Use delegation for `onSubmit` and `onReset` events. ([@gaearon](https://github.com/gaearon) in [#19333](https://github.com/facebook/react/pull/19333))818* Improve memory usage. ([@trueadm](https://github.com/trueadm) in [#18970](https://github.com/facebook/react/pull/18970))819820### React DOM Server821822* Make `useCallback` behavior consistent with `useMemo` for the server renderer. ([@alexmckenley](https://github.com/alexmckenley) in [#18783](https://github.com/facebook/react/pull/18783))823* Fix state leaking when a function component throws. ([@pmaccart](https://github.com/pmaccart) in [#19212](https://github.com/facebook/react/pull/19212))824825### React Test Renderer826827* Improve `findByType` error message. ([@henryqdineen](https://github.com/henryqdineen) in [#17439](https://github.com/facebook/react/pull/17439))828829### Concurrent Mode (Experimental)830831* Revamp the priority batching heuristics. ([@acdlite](https://github.com/acdlite) in [#18796](https://github.com/facebook/react/pull/18796))832* Add the `unstable_` prefix before the experimental APIs. ([@acdlite](https://github.com/acdlite) in [#18825](https://github.com/facebook/react/pull/18825))833* Remove `unstable_discreteUpdates` and `unstable_flushDiscreteUpdates`. ([@trueadm](https://github.com/trueadm) in [#18825](https://github.com/facebook/react/pull/18825))834* Remove the `timeoutMs` argument. ([@acdlite](https://github.com/acdlite) in [#19703](https://github.com/facebook/react/pull/19703))835* Disable `<div hidden />` prerendering in favor of a different future API. ([@acdlite](https://github.com/acdlite) in [#18917](https://github.com/facebook/react/pull/18917))836* Add `unstable_expectedLoadTime` to Suspense for CPU-bound trees. ([@acdlite](https://github.com/acdlite) in [#19936](https://github.com/facebook/react/pull/19936))837* Add an experimental `unstable_useOpaqueIdentifier` Hook. ([@lunaruan](https://github.com/lunaruan) in [#17322](https://github.com/facebook/react/pull/17322))838* Add an experimental `unstable_startTransition` API. ([@rickhanlonii](https://github.com/rickhanlonii) in [#19696](https://github.com/facebook/react/pull/19696))839* Using `act` in the test renderer no longer flushes Suspense fallbacks. ([@acdlite](https://github.com/acdlite) in [#18596](https://github.com/facebook/react/pull/18596))840* Use global render timeout for CPU Suspense. ([@sebmarkbage](https://github.com/sebmarkbage) in [#19643](https://github.com/facebook/react/pull/19643))841* Clear the existing root content before mounting. ([@bvaughn](https://github.com/bvaughn) in [#18730](https://github.com/facebook/react/pull/18730))842* Fix a bug with error boundaries. ([@acdlite](https://github.com/acdlite) in [#18265](https://github.com/facebook/react/pull/18265))843* Fix a bug causing dropped updates in a suspended tree. ([@acdlite](https://github.com/acdlite) in [#18384](https://github.com/facebook/react/pull/18384) and [#18457](https://github.com/facebook/react/pull/18457))844* Fix a bug causing dropped render phase updates. ([@acdlite](https://github.com/acdlite) in [#18537](https://github.com/facebook/react/pull/18537))845* Fix a bug in SuspenseList. ([@sebmarkbage](https://github.com/sebmarkbage) in [#18412](https://github.com/facebook/react/pull/18412))846* Fix a bug causing Suspense fallback to show too early. ([@acdlite](https://github.com/acdlite) in [#18411](https://github.com/facebook/react/pull/18411))847* Fix a bug with class components inside SuspenseList. ([@sebmarkbage](https://github.com/sebmarkbage) in [#18448](https://github.com/facebook/react/pull/18448))848* Fix a bug with inputs that may cause updates to be dropped. ([@jddxf](https://github.com/jddxf) in [#18515](https://github.com/facebook/react/pull/18515) and [@acdlite](https://github.com/acdlite) in [#18535](https://github.com/facebook/react/pull/18535))849* Fix a bug causing Suspense fallback to get stuck.  ([@acdlite](https://github.com/acdlite) in [#18663](https://github.com/facebook/react/pull/18663))850* Don't cut off the tail of a SuspenseList if hydrating. ([@sebmarkbage](https://github.com/sebmarkbage) in [#18854](https://github.com/facebook/react/pull/18854))851* Fix a bug in `useMutableSource` that may happen when `getSnapshot` changes. ([@bvaughn](https://github.com/bvaughn) in [#18297](https://github.com/facebook/react/pull/18297))852* Fix a tearing bug in `useMutableSource`. ([@bvaughn](https://github.com/bvaughn) in [#18912](https://github.com/facebook/react/pull/18912))853* Warn if calling setState outside of render but before commit. ([@sebmarkbage](https://github.com/sebmarkbage) in [#18838](https://github.com/facebook/react/pull/18838))854855## 16.14.0 (October 14, 2020)856857### React858859* Add support for the [new JSX transform](https://reactjs.org/blog/2020/09/22/introducing-the-new-jsx-transform.html). ([@lunaruan](https://github.com/lunaruan) in [#18299](https://github.com/facebook/react/pull/18299))860861## 16.13.1 (March 19, 2020)862863### React DOM864865* Fix bug in legacy mode Suspense where effect clean-up functions are not fired. This only affects users who use Suspense for data fetching in legacy mode, which is not technically supported. ([@acdlite](https://github.com/acdlite) in [#18238](https://github.com/facebook/react/pull/18238))866* Revert warning for cross-component updates that happen inside class render lifecycles (`componentWillReceiveProps`, `shouldComponentUpdate`, and so on). ([@gaearon](https://github.com/gaearon) in [#18330](https://github.com/facebook/react/pull/18330))867868## 16.13.0 (February 26, 2020)869870### React871872* Warn when a string ref is used in a manner that's not amenable to a future codemod ([@lunaruan](https://github.com/lunaruan) in [#17864](https://github.com/facebook/react/pull/17864))873* Deprecate `React.createFactory()` ([@trueadm](https://github.com/trueadm) in [#17878](https://github.com/facebook/react/pull/17878))874875### React DOM876877* Warn when changes in `style` may cause an unexpected collision ([@sophiebits](https://github.com/sophiebits) in [#14181](https://github.com/facebook/react/pull/14181), [#18002](https://github.com/facebook/react/pull/18002))878* Warn when a function component is updated during another component's render phase ([@acdlite](https://github.com/acdlite) in [#17099](https://github.com/facebook/react/pull/17099))879* Deprecate `unstable_createPortal` ([@trueadm](https://github.com/trueadm) in [#17880](https://github.com/facebook/react/pull/17880))880* Fix `onMouseEnter` being fired on disabled buttons ([@AlfredoGJ](https://github.com/AlfredoGJ) in [#17675](https://github.com/facebook/react/pull/17675))881* Call `shouldComponentUpdate` twice when developing in `StrictMode` ([@bvaughn](https://github.com/bvaughn) in [#17942](https://github.com/facebook/react/pull/17942))882* Add `version` property to ReactDOM ([@ealush](https://github.com/ealush) in [#15780](https://github.com/facebook/react/pull/15780))883* Don't call `toString()` of `dangerouslySetInnerHTML` ([@sebmarkbage](https://github.com/sebmarkbage) in [#17773](https://github.com/facebook/react/pull/17773))884* Show component stacks in more warnings ([@gaearon](https://github.com/gaearon) in [#17922](https://github.com/facebook/react/pull/17922), [#17586](https://github.com/facebook/react/pull/17586))885886### Concurrent Mode (Experimental)887888* Warn for problematic usages of `ReactDOM.createRoot()` ([@trueadm](https://github.com/trueadm) in [#17937](https://github.com/facebook/react/pull/17937))889* Remove `ReactDOM.createRoot()` callback params and added warnings on usage ([@bvaughn](https://github.com/bvaughn) in [#17916](https://github.com/facebook/react/pull/17916))890* Don't group Idle/Offscreen work with other work ([@sebmarkbage](https://github.com/sebmarkbage) in [#17456](https://github.com/facebook/react/pull/17456))891* Adjust `SuspenseList` CPU bound heuristic ([@sebmarkbage](https://github.com/sebmarkbage) in [#17455](https://github.com/facebook/react/pull/17455))892* Add missing event plugin priorities ([@trueadm](https://github.com/trueadm) in [#17914](https://github.com/facebook/react/pull/17914))893* Fix `isPending` only being true when transitioning from inside an input event ([@acdlite](https://github.com/acdlite) in [#17382](https://github.com/facebook/react/pull/17382))894* Fix `React.memo` components dropping updates when interrupted by a higher priority update ([@acdlite]((https://github.com/acdlite)) in [#18091](https://github.com/facebook/react/pull/18091))895* Don't warn when suspending at the wrong priority ([@gaearon](https://github.com/gaearon) in [#17971](https://github.com/facebook/react/pull/17971))896* Fix a bug with rebasing updates ([@acdlite](https://github.com/acdlite) and [@sebmarkbage](https://github.com/sebmarkbage) in [#17560](https://github.com/facebook/react/pull/17560), [#17510](https://github.com/facebook/react/pull/17510), [#17483](https://github.com/facebook/react/pull/17483), [#17480](https://github.com/facebook/react/pull/17480))897898## 16.12.0 (November 14, 2019)899900### React DOM901902* Fix passive effects (`useEffect`) not being fired in a multi-root app. ([@acdlite](https://github.com/acdlite) in [#17347](https://github.com/facebook/react/pull/17347))903904### React Is905906* Fix `lazy` and `memo` types considered elements instead of components ([@bvaughn](https://github.com/bvaughn) in [#17278](https://github.com/facebook/react/pull/17278))907908## 16.11.0 (October 22, 2019)909910### React DOM911912* Fix `mouseenter` handlers from firing twice inside nested React containers. [@yuanoook](https://github.com/yuanoook) in [#16928](https://github.com/facebook/react/pull/16928)913* Remove `unstable_createRoot` and `unstable_createSyncRoot` experimental APIs. (These are available in the Experimental channel as `createRoot` and `createSyncRoot`.) ([@acdlite](http://github.com/acdlite) in [#17088](https://github.com/facebook/react/pull/17088))914915## 16.10.2 (October 3, 2019)916917### React DOM918919* Fix regression in react-native-web by restoring order of arguments in event plugin extractors ([@necolas](https://github.com/necolas) in [#16978](https://github.com/facebook/react/pull/16978))920921## 16.10.1 (September 28, 2019)922923### React DOM924925* Fix regression in Next.js apps by allowing Suspense mismatch during hydration to silently proceed ([@sebmarkbage](https://github.com/sebmarkbage) in [#16943](https://github.com/facebook/react/pull/16943))926927## 16.10.0 (September 27, 2019)928929### React DOM930931* Fix edge case where a hook update wasn't being memoized. ([@sebmarkbage](http://github.com/sebmarkbage) in [#16359](https://github.com/facebook/react/pull/16359))932* Fix heuristic for determining when to hydrate, so we don't incorrectly hydrate during an update. ([@sebmarkbage](http://github.com/sebmarkbage) in [#16739](https://github.com/facebook/react/pull/16739))933* Clear additional fiber fields during unmount to save memory. ([@trueadm](http://github.com/trueadm) in [#16807](https://github.com/facebook/react/pull/16807))934* Fix bug with required text fields in Firefox. ([@halvves](http://github.com/halvves) in [#16578](https://github.com/facebook/react/pull/16578))935* Prefer `Object.is` instead of inline polyfill, when available. ([@ku8ar](http://github.com/ku8ar) in [#16212](https://github.com/facebook/react/pull/16212))936* Fix bug when mixing Suspense and error handling. ([@acdlite](http://github.com/acdlite) in [#16801](https://github.com/facebook/react/pull/16801))937938939### Scheduler (Experimental)940941* Improve queue performance by switching its internal data structure to a min binary heap. ([@acdlite](http://github.com/acdlite) in [#16245](https://github.com/facebook/react/pull/16245))942* Use `postMessage` loop with short intervals instead of attempting to align to frame boundaries with `requestAnimationFrame`. ([@acdlite](http://github.com/acdlite) in [#16214](https://github.com/facebook/react/pull/16214))943944### useSubscription945946* Avoid tearing issue when a mutation happens and the previous update is still in progress. ([@bvaughn](http://github.com/bvaughn) in [#16623](https://github.com/facebook/react/pull/16623))947948## 16.9.0 (August 8, 2019)949950### React951952* Add `<React.Profiler>` API for gathering performance measurements programmatically. ([@bvaughn](https://github.com/bvaughn) in [#15172](https://github.com/facebook/react/pull/15172))953* Remove `unstable_ConcurrentMode` in favor of `unstable_createRoot`. ([@acdlite](https://github.com/acdlite) in [#15532](https://github.com/facebook/react/pull/15532))954955### React DOM956957* Deprecate old names for the `UNSAFE_*` lifecycle methods. ([@bvaughn](https://github.com/bvaughn) in [#15186](https://github.com/facebook/react/pull/15186) and [@threepointone](https://github.com/threepointone) in [#16103](https://github.com/facebook/react/pull/16103))958* Deprecate `javascript:` URLs as a common attack surface. ([@sebmarkbage](https://github.com/sebmarkbage) in [#15047](https://github.com/facebook/react/pull/15047))959* Deprecate uncommon "module pattern" (factory) components. ([@sebmarkbage](https://github.com/sebmarkbage) in [#15145](https://github.com/facebook/react/pull/15145))960* Add support for the `disablePictureInPicture` attribute on `<video>`. ([@eek](https://github.com/eek) in [#15334](https://github.com/facebook/react/pull/15334))961* Add support for `onLoad` event for `<embed>`. ([@cherniavskii](https://github.com/cherniavskii) in [#15614](https://github.com/facebook/react/pull/15614))962* Add support for editing `useState` state from DevTools. ([@bvaughn](https://github.com/bvaughn) in [#14906](https://github.com/facebook/react/pull/14906))963* Add support for toggling Suspense from DevTools. ([@gaearon](https://github.com/gaearon) in [#15232](https://github.com/facebook/react/pull/15232))964* Warn when `setState` is called from `useEffect`, creating a loop. ([@gaearon](https://github.com/gaearon) in [#15180](https://github.com/facebook/react/pull/15180))965* Fix a memory leak. ([@paulshen](https://github.com/paulshen) in [#16115](https://github.com/facebook/react/pull/16115))966* Fix a crash inside `findDOMNode` for components wrapped in `<Suspense>`. ([@acdlite](https://github.com/acdlite) in [#15312](https://github.com/facebook/react/pull/15312))967* Fix pending effects from being flushed too late. ([@acdlite](https://github.com/acdlite) in [#15650](https://github.com/facebook/react/pull/15650))968* Fix incorrect argument order in a warning message. ([@brickspert](https://github.com/brickspert) in [#15345](https://github.com/facebook/react/pull/15345))969* Fix hiding Suspense fallback nodes when there is an `!important` style. ([@acdlite](https://github.com/acdlite) in [#15861](https://github.com/facebook/react/pull/15861) and [#15882](https://github.com/facebook/react/pull/15882))970* Slightly improve hydration performance. ([@bmeurer](https://github.com/bmeurer) in [#15998](https://github.com/facebook/react/pull/15998))971972### React DOM Server973974* Fix incorrect output for camelCase custom CSS property names. ([@bedakb](https://github.com/bedakb) in [#16167](https://github.com/facebook/react/pull/16167))975976### React Test Utilities and Test Renderer977978* Add `act(async () => ...)` for testing asynchronous state updates. ([@threepointone](https://github.com/threepointone) in [#14853](https://github.com/facebook/react/pull/14853))979* Add support for nesting `act` from different renderers. ([@threepointone](https://github.com/threepointone) in [#16039](https://github.com/facebook/react/pull/16039) and [#16042](https://github.com/facebook/react/pull/16042))980* Warn in Strict Mode if effects are scheduled outside an `act()` call. ([@threepointone](https://github.com/threepointone) in [#15763](https://github.com/facebook/react/pull/15763) and [#16041](https://github.com/facebook/react/pull/16041))981* Warn when using `act` from the wrong renderer. ([@threepointone](https://github.com/threepointone) in [#15756](https://github.com/facebook/react/pull/15756))982983### ESLint Plugin: React Hooks984985* Report Hook calls at the top level as a violation. ([gaearon](https://github.com/gaearon) in [#16455](https://github.com/facebook/react/pull/16455))986987## 16.8.6 (March 27, 2019)988989### React DOM990991* Fix an incorrect bailout in `useReducer()`. ([@acdlite](https://github.com/acdlite) in [#15124](https://github.com/facebook/react/pull/15124))992* Fix iframe warnings in Safari DevTools. ([@renanvalentin](https://github.com/renanvalentin) in [#15099](https://github.com/facebook/react/pull/15099))993* Warn if `contextType` is set to `Context.Consumer` instead of `Context`. ([@aweary](https://github.com/aweary) in [#14831](https://github.com/facebook/react/pull/14831))994* Warn if `contextType` is set to invalid values. ([@gaearon](https://github.com/gaearon) in [#15142](https://github.com/facebook/react/pull/15142))995996## 16.8.5 (March 22, 2019)997998### React DOM9991000* Don't set the first option as selected in select tag with `size` attribute. ([@kulek1](https://github.com/kulek1) in [#14242](https://github.com/facebook/react/pull/14242))1001* Improve the `useEffect(async () => ...)` warning message. ([@gaearon](https://github.com/gaearon) in [#15118](https://github.com/facebook/react/pull/15118))1002* Improve the error message sometimes caused by duplicate React. ([@jaredpalmer](https://github.com/jaredpalmer) in [#15139](https://github.com/facebook/react/pull/15139))10031004### React DOM Server10051006* Improve the `useLayoutEffect` warning message when server rendering. ([@gaearon](https://github.com/gaearon) in [#15158](https://github.com/facebook/react/pull/15158))10071008### React Shallow Renderer10091010* Fix `setState` in shallow renderer to work with Hooks. ([@gaearon](https://github.com/gaearon) in [#15120](https://github.com/facebook/react/pull/15120))1011* Fix shallow renderer to support `React.memo`. ([@aweary](https://github.com/aweary) in [#14816](https://github.com/facebook/react/pull/14816))1012* Fix shallow renderer to support Hooks inside `forwardRef`. ([@eps1lon](https://github.com/eps1lon) in [#15100](https://github.com/facebook/react/pull/15100))10131014## 16.8.4 (March 5, 2019)10151016### React DOM and other renderers10171018- Fix a bug where DevTools caused a runtime error when inspecting a component that used a `useContext` hook. ([@bvaughn](https://github.com/bvaughn) in [#14940](https://github.com/facebook/react/pull/14940))10191020## 16.8.3 (February 21, 2019)10211022### React DOM10231024* Fix a bug that caused inputs to behave incorrectly in UMD builds. ([@gaearon](https://github.com/gaearon) in [#14914](https://github.com/facebook/react/pull/14914))1025* Fix a bug that caused render phase updates to be discarded. ([@gaearon](https://github.com/gaearon) in [#14852](https://github.com/facebook/react/pull/14852))10261027### React DOM Server1028* Unwind the context stack when a stream is destroyed without completing, to prevent incorrect values during a subsequent render. ([@overlookmotel](https://github.com/overlookmotel) in [#14706](https://github.com/facebook/react/pull/14706/))10291030### ESLint Plugin for React Hooks10311032* Add a new recommended `exhaustive-deps` rule. ([@gaearon](https://github.com/gaearon) in [#14636](https://github.com/facebook/react/pull/14636))10331034## 16.8.2 (February 14, 2019)10351036### React DOM10371038* Fix `ReactDOM.render` being ignored inside `useEffect`. ([@gaearon](https://github.com/gaearon) in [#14799](https://github.com/facebook/react/pull/14799))1039* Fix a crash when unmounting empty portals. ([@gaearon](https://github.com/gaearon) in [#14820](https://github.com/facebook/react/pull/14820))1040* Fix `useImperativeHandle` to work correctly when no deps are specified. ([@gaearon](https://github.com/gaearon) in [#14801](https://github.com/facebook/react/pull/14801))1041* Fix `crossOrigin` attribute to work in SVG `image` elements. ([@aweary](https://github.com/aweary) in [#14832](https://github.com/facebook/react/pull/14832))1042* Fix a false positive warning when using Suspense with Hooks. ([@gaearon](https://github.com/gaearon) in [#14821](https://github.com/facebook/react/pull/14821))10431044### React Test Utils and React Test Renderer10451046* Include component stack into the `act()` warning. ([@threepointone](https://github.com/threepointone) in [#14855](https://github.com/facebook/react/pull/14855))10471048## 16.8.1 (February 6, 2019)10491050### React DOM and React Test Renderer10511052* Fix a crash when used together with an older version of React. ([@bvaughn](https://github.com/bvaughn) in [#14770](https://github.com/facebook/react/pull/14770))10531054### React Test Utils10551056* Fix a crash in Node environment. ([@threepointone](https://github.com/threepointone) in [#14768](https://github.com/facebook/react/pull/14768))10571058## 16.8.0 (February 6, 2019)10591060### React10611062* Add [Hooks](https://reactjs.org/docs/hooks-intro.html) — a way to use state and other React features without writing a class. ([@acdlite](https://github.com/acdlite) et al. in [#13968](https://github.com/facebook/react/pull/13968))1063* Improve the `useReducer` Hook lazy initialization API. ([@acdlite](https://github.com/acdlite) in [#14723](https://github.com/facebook/react/pull/14723))10641065### React DOM10661067* Bail out of rendering on identical values for `useState` and `useReducer` Hooks. ([@acdlite](https://github.com/acdlite) in [#14569](https://github.com/facebook/react/pull/14569))1068* Use `Object.is` algorithm for comparing `useState` and `useReducer` values. ([@Jessidhia](https://github.com/Jessidhia) in [#14752](https://github.com/facebook/react/pull/14752))1069* Don’t compare the first argument passed to `useEffect`/`useMemo`/`useCallback` Hooks. ([@acdlite](https://github.com/acdlite) in [#14594](https://github.com/facebook/react/pull/14594))1070* Support synchronous thenables passed to `React.lazy()`. ([@gaearon](https://github.com/gaearon) in [#14626](https://github.com/facebook/react/pull/14626))1071* Render components with Hooks twice in Strict Mode (DEV-only) to match class behavior. ([@gaearon](https://github.com/gaearon) in [#14654](https://github.com/facebook/react/pull/14654))1072* Warn about mismatching Hook order in development. ([@threepointone](https://github.com/threepointone) in [#14585](https://github.com/facebook/react/pull/14585) and [@acdlite](https://github.com/acdlite) in [#14591](https://github.com/facebook/react/pull/14591))1073* Effect clean-up functions must return either `undefined` or a function. All other values, including `null`, are not allowed. [@acdlite](https://github.com/acdlite) in [#14119](https://github.com/facebook/react/pull/14119)10741075### React Test Renderer and Test Utils10761077* Support Hooks in the shallow renderer. ([@trueadm](https://github.com/trueadm) in [#14567](https://github.com/facebook/react/pull/14567))1078* Fix wrong state in `shouldComponentUpdate` in the presence of `getDerivedStateFromProps` for Shallow Renderer. ([@chenesan](https://github.com/chenesan) in [#14613](https://github.com/facebook/react/pull/14613))1079* Add `ReactTestRenderer.act()` and `ReactTestUtils.act()` for batching updates so that tests more closely match real behavior. ([@threepointone](https://github.com/threepointone) in [#14744](https://github.com/facebook/react/pull/14744))108010811082### ESLint Plugin: React Hooks10831084* Initial [release](https://www.npmjs.com/package/eslint-plugin-react-hooks). ([@calebmer](https://github.com/calebmer) in [#13968](https://github.com/facebook/react/pull/13968))1085* Fix reporting after encountering a loop. ([@calebmer](https://github.com/calebmer) and [@Yurickh](https://github.com/Yurickh) in [#14661](https://github.com/facebook/react/pull/14661))1086* Don't consider throwing to be a rule violation. ([@sophiebits](https://github.com/sophiebits) in [#14040](https://github.com/facebook/react/pull/14040))10871088## 16.7.0 (December 19, 2018)10891090### React DOM10911092* Fix performance of `React.lazy` for large numbers of lazily-loaded components. ([@acdlite](http://github.com/acdlite) in [#14429](https://github.com/facebook/react/pull/14429))1093* Clear fields on unmount to avoid memory leaks. ([@trueadm](http://github.com/trueadm) in [#14276](https://github.com/facebook/react/pull/14276))1094* Fix bug with SSR and context when mixing `react-dom/server@16.6` and `react@<16.6`. ([@gaearon](http://github.com/gaearon) in [#14291](https://github.com/facebook/react/pull/14291))1095* Fix a performance regression in profiling mode. ([@bvaughn](http://github.com/bvaughn) in [#14383](https://github.com/facebook/react/pull/14383))10961097### Scheduler (Experimental)10981099* Post to MessageChannel instead of window. ([@acdlite](http://github.com/acdlite) in [#14234](https://github.com/facebook/react/pull/14234))1100* Reduce serialization overhead. ([@developit](http://github.com/developit) in [#14249](https://github.com/facebook/react/pull/14249))1101* Fix fallback to `setTimeout` in testing environments. ([@bvaughn](http://github.com/bvaughn) in [#14358](https://github.com/facebook/react/pull/14358))1102* Add methods for debugging. ([@mrkev](http://github.com/mrkev) in [#14053](https://github.com/facebook/react/pull/14053))110311041105## 16.6.3 (November 12, 2018)11061107### React DOM11081109* Fix bugs in `Suspense` and `lazy`. ([@acdlite](https://github.com/acdlite) in [#14133](https://github.com/facebook/react/pull/14133), [#14157](https://github.com/facebook/react/pull/14157), and [#14164](https://github.com/facebook/react/pull/14164))1110* Fix highlighting of `React.memo` updates in React DevTools. ([@bvaughn](https://github.com/bvaughn) in [#14141](https://github.com/facebook/react/pull/14141))1111* Fix interaction of Suspense with the React Profiler. ([@bvaughn](https://github.com/bvaughn) in [#14065](https://github.com/facebook/react/pull/14065))1112* Fix a false positive warning when using Suspense. ([@acdlite](https://github.com/acdlite) in [#14158](https://github.com/facebook/react/pull/14158))11131114### React DOM Server11151116* Fix incorrect sharing of context state between `renderToNodeStream()` calls. ([@sebmarkbage](https://github.com/sebmarkbage) in [#14182](https://github.com/facebook/react/pull/14182))1117* Add a warning about incorrect usage of the context API. ([@trueadm](https://github.com/trueadm) in [#14033](https://github.com/facebook/react/pull/14033))11181119## 16.6.2 (November 12, 2018)11201121This release was published in a broken state and should be skipped.11221123## 16.6.1 (November 6, 2018)11241125### React DOM11261127* Fallback should not remount every time a promise resolves. ([@acdlite](https://github.com/acdlite) in [#14083](https://github.com/facebook/react/pull/14083))1128* Fix bug where Suspense keeps showing fallback even after everything finishes loading. ([@acdlite](https://github.com/acdlite) in [#14083](https://github.com/facebook/react/pull/14083))1129* Fix a crash when Suspense finishes loading in IE11. ([@sophiebits](https://github.com/sophiebits) in [#14126](https://github.com/facebook/react/pull/14126))1130* Fix unresolved default props in lifecycle methods of a lazy component. ([@gaearon](https://github.com/gaearon) in [#14112](https://github.com/facebook/react/pull/14112))1131* Fix bug when recovering from an error thrown during complete phase. ([@gaearon](https://github.com/gaearon) in [#14104](https://github.com/facebook/react/pull/14104))11321133### Scheduler (Experimental)11341135* Switch from deadline object to `shouldYield` API. ([@acdlite](https://github.com/acdlite) in [#14025](https://github.com/facebook/react/pull/14025))113611371138## 16.6.0 (October 23, 2018)11391140### React11411142* Add `React.memo()` as an alternative to `PureComponent` for functions. ([@acdlite](https://github.com/acdlite) in [#13748](https://github.com/facebook/react/pull/13748))1143* Add `React.lazy()` for code splitting components. ([@acdlite](https://github.com/acdlite) in [#13885](https://github.com/facebook/react/pull/13885))1144* `React.StrictMode` now warns about legacy context API. ([@bvaughn](https://github.com/bvaughn) in [#13760](https://github.com/facebook/react/pull/13760))1145* `React.StrictMode` now warns about `findDOMNode`. ([@sebmarkbage](https://github.com/sebmarkbage) in [#13841](https://github.com/facebook/react/pull/13841))1146* Rename `unstable_AsyncMode` to `unstable_ConcurrentMode`. ([@trueadm](https://github.com/trueadm) in [#13732](https://github.com/facebook/react/pull/13732))1147* Rename `unstable_Placeholder` to `Suspense`, and `delayMs` to `maxDuration`. ([@gaearon](https://github.com/gaearon) in [#13799](https://github.com/facebook/react/pull/13799) and [@sebmarkbage](https://github.com/sebmarkbage) in [#13922](https://github.com/facebook/react/pull/13922))11481149### React DOM11501151* Add `contextType` as a more ergonomic way to subscribe to context from a class. ([@bvaughn](https://github.com/bvaughn) in [#13728](https://github.com/facebook/react/pull/13728))1152* Add `getDerivedStateFromError` lifecycle method for catching errors in a future asynchronous server-side renderer. ([@bvaughn](https://github.com/bvaughn) in [#13746](https://github.com/facebook/react/pull/13746))1153* Warn when `<Context>` is used instead of `<Context.Consumer>`. ([@trueadm](https://github.com/trueadm) in [#13829](https://github.com/facebook/react/pull/13829))1154* Fix gray overlay on iOS Safari. ([@philipp-spiess](https://github.com/philipp-spiess) in [#13778](https://github.com/facebook/react/pull/13778))1155* Fix a bug caused by overwriting `window.event` in development. ([@sergei-startsev](https://github.com/sergei-startsev) in [#13697](https://github.com/facebook/react/pull/13697))11561157### React DOM Server11581159* Add support for `React.memo()`. ([@alexmckenley](https://github.com/alexmckenley) in [#13855](https://github.com/facebook/react/pull/13855))1160* Add support for `contextType`. ([@alexmckenley](https://github.com/alexmckenley) and [@sebmarkbage](https://github.com/sebmarkbage) in [#13889](https://github.com/facebook/react/pull/13889))11611162### Scheduler (Experimental)11631164* Rename the package to `scheduler`. ([@gaearon](https://github.com/gaearon) in [#13683](https://github.com/facebook/react/pull/13683))1165* Support priority levels, continuations, and wrapped callbacks. ([@acdlite](https://github.com/acdlite) in [#13720](https://github.com/facebook/react/pull/13720) and [#13842](https://github.com/facebook/react/pull/13842))1166* Improve the fallback mechanism in non-DOM environments. ([@acdlite](https://github.com/acdlite) in [#13740](https://github.com/facebook/react/pull/13740))1167* Schedule `requestAnimationFrame` earlier. ([@acdlite](https://github.com/acdlite) in [#13785](https://github.com/facebook/react/pull/13785))1168* Fix the DOM detection to be more thorough. ([@trueadm](https://github.com/trueadm) in [#13731](https://github.com/facebook/react/pull/13731))1169* Fix bugs with interaction tracing. ([@bvaughn](https://github.com/bvaughn) in [#13590](https://github.com/facebook/react/pull/13590))1170* Add the `envify` transform to the package. ([@mridgway](https://github.com/mridgway) in [#13766](https://github.com/facebook/react/pull/13766))11711172## 16.5.2 (September 18, 2018)11731174### React DOM11751176* Fixed a recent `<iframe>` regression ([@JSteunou](https://github.com/JSteunou) in [#13650](https://github.com/facebook/react/pull/13650))1177* Fix `updateWrapper` so that `<textarea>`s no longer re-render when data is unchanged ([@joelbarbosa](https://github.com/joelbarbosa) in [#13643](https://github.com/facebook/react/pull/13643))11781179### Schedule (Experimental)11801181* Renaming "tracking" API to "tracing" ([@bvaughn](https://github.com/bvaughn) in [#13641](https://github.com/facebook/react/pull/13641))1182* Add UMD production+profiling entry points ([@bvaughn](https://github.com/bvaughn) in [#13642](https://github.com/facebook/react/pull/13642))1183* Refactored `schedule` to remove some React-isms and improve performance for when deferred updates time out ([@acdlite](https://github.com/acdlite) in [#13582](https://github.com/facebook/react/pull/13582))11841185## 16.5.1 (September 13, 2018)11861187### React11881189* Improve the warning when `React.forwardRef` receives an unexpected number of arguments. ([@andresroberto](https://github.com/andresroberto) in [#13636](https://github.com/facebook/react/issues/13636))11901191### React DOM11921193* Fix a regression in unstable exports used by React Native Web. ([@aweary](https://github.com/aweary) in [#13598](https://github.com/facebook/react/issues/13598))1194* Fix a crash when component defines a method called `isReactComponent`. ([@gaearon](https://github.com/gaearon) in [#13608](https://github.com/facebook/react/issues/13608))1195* Fix a crash in development mode in IE9 when printing a warning. ([@link-alex](https://github.com/link-alex) in [#13620](https://github.com/facebook/react/issues/13620))1196* Provide a better error message when running `react-dom/profiling` with `schedule/tracking`. ([@bvaughn](https://github.com/bvaughn) in [#13605](https://github.com/facebook/react/issues/13605))1197* If a `ForwardRef` component defines a `displayName`, use it in warnings. ([@probablyup](https://github.com/probablyup) in [#13615](https://github.com/facebook/react/issues/13615))11981199### Schedule (Experimental)12001201* Add a separate profiling entry point at `schedule/tracking-profiling`. ([@bvaughn](https://github.com/bvaughn) in [#13605](https://github.com/facebook/react/issues/13605))12021203## 16.5.0 (September 5, 2018)12041205### React12061207* Add a warning if `React.forwardRef` render function doesn't take exactly two arguments ([@bvaughn](https://github.com/bvaughn) in [#13168](https://github.com/facebook/react/issues/13168))1208* Improve the error message when passing an element to `createElement` by mistake ([@DCtheTall](https://github.com/DCtheTall) in [#13131](https://github.com/facebook/react/issues/13131))1209* Don't call profiler `onRender` until after mutations ([@bvaughn](https://github.com/bvaughn) in [#13572](https://github.com/facebook/react/issues/13572))12101211### React DOM12121213* Add support for React DevTools Profiler ([@bvaughn](https://github.com/bvaughn) in [#13058](https://github.com/facebook/react/issues/13058))1214* Add `react-dom/profiling` entry point alias for profiling in production ([@bvaughn](https://github.com/bvaughn) in [#13570](https://github.com/facebook/react/issues/13570))1215* Add `onAuxClick` event for browsers that support it ([@jquense](https://github.com/jquense) in [#11571](https://github.com/facebook/react/issues/11571))1216* Add `movementX` and `movementY` fields to mouse events ([@jasonwilliams](https://github.com/jasonwilliams) in [#9018](https://github.com/facebook/react/issues/9018))1217* Add `tangentialPressure` and `twist` fields to pointer events ([@motiz88](https://github.com/motiz88) in [#13374](https://github.com/facebook/react/issues/13374))1218* Minimally support iframes (nested browsing contexts) in selection event handling ([@acusti](https://github.com/acusti) in [#12037](https://github.com/facebook/react/issues/12037))1219* Support passing booleans to the `focusable` SVG attribute ([@gaearon](https://github.com/gaearon) in [#13339](https://github.com/facebook/react/issues/13339))1220* Ignore `<noscript>` on the client when hydrating ([@Ephem](https://github.com/Ephem) in [#13537](https://github.com/facebook/react/issues/13537))1221* Fix `gridArea` to be treated as a unitless CSS property ([@mgol](https://github.com/mgol) in [#13550](https://github.com/facebook/react/issues/13550))1222* Fix incorrect data in `compositionend` event when typing Korean on IE11 ([@crux153](https://github.com/crux153) in [#12563](https://github.com/facebook/react/issues/12563))1223* Fix a crash when using dynamic `children` in the `<option>` tag ([@Slowyn](https://github.com/Slowyn) in [#13261](https://github.com/facebook/react/issues/13261), [@gaearon](https://github.com/gaearon) in [#13465](https://github.com/facebook/react/pull/13465))1224* Fix the `checked` attribute not getting initially set on the `input` ([@dilidili](https://github.com/dilidili) in [#13114](https://github.com/facebook/react/issues/13114))1225* Fix hydration of `dangerouslySetInnerHTML` when `__html` is not a string ([@gaearon](https://github.com/gaearon) in [#13353](https://github.com/facebook/react/issues/13353))1226* Fix a warning about missing controlled `onChange` to fire on falsy values too ([@nicolevy](https://github.com/nicolevy) in [#12628](https://github.com/facebook/react/issues/12628))1227* Fix `submit` and `reset` buttons getting an empty label ([@ellsclytn](https://github.com/ellsclytn) in [#12780](https://github.com/facebook/react/issues/12780))1228* Fix the `onSelect` event not being triggered after drag and drop ([@gaearon](https://github.com/gaearon) in [#13422](https://github.com/facebook/react/issues/13422))1229* Fix the `onClick` event not working inside a portal on iOS ([@aweary](https://github.com/aweary) in [#11927](https://github.com/facebook/react/issues/11927))1230* Fix a performance issue when thousands of roots are re-rendered ([@gaearon](https://github.com/gaearon) in [#13335](https://github.com/facebook/react/issues/13335))1231* Fix a performance regression that also caused `onChange` to not fire in some cases ([@gaearon](https://github.com/gaearon) in [#13423](https://github.com/facebook/react/issues/13423))1232* Handle errors in more edge cases gracefully ([@gaearon](https://github.com/gaearon) in [#13237](https://github.com/facebook/react/issues/13237) and [@acdlite](https://github.com/acdlite) in [#13269](https://github.com/facebook/react/issues/13269))1233* Don't use proxies for synthetic events in development ([@gaearon](https://github.com/gaearon) in [#12171](https://github.com/facebook/react/issues/12171))1234* Warn when `"false"` or `"true"` is the value of a boolean DOM prop ([@motiz88](https://github.com/motiz88) in [#13372](https://github.com/facebook/react/issues/13372))1235* Warn when `this.state` is initialized to `props` ([@veekas](https://github.com/veekas) in [#11658](https://github.com/facebook/react/issues/11658))1236* Don't compare `style` on hydration in IE due to noisy false positives ([@mgol](https://github.com/mgol) in [#13534](https://github.com/facebook/react/issues/13534))1237* Include `StrictMode` in the component stack ([@gaearon](https://github.com/gaearon) in [#13240](https://github.com/facebook/react/issues/13240))1238* Don't overwrite `window.event` in IE ([@ConradIrwin](https://github.com/ConradIrwin) in [#11696](https://github.com/facebook/react/issues/11696))1239* Improve component stack for the `folder/index.js` naming convention ([@gaearon](https://github.com/gaearon) in [#12059](https://github.com/facebook/react/issues/12059))1240* Improve a warning when using `getDerivedStateFromProps` without initialized state ([@flxwu](https://github.com/flxwu) in [#13317](https://github.com/facebook/react/issues/13317))1241* Improve a warning about invalid textarea usage ([@raunofreiberg](https://github.com/raunofreiberg) in [#13361](https://github.com/facebook/react/issues/13361))1242* Treat invalid Symbol and function values more consistently ([@raunofreiberg](https://github.com/raunofreiberg) in [#13362](https://github.com/facebook/react/issues/13362) and [#13389](https://github.com/facebook/react/issues/13389))1243* Allow Electron `<webview>` tag without warnings ([@philipp-spiess](https://github.com/philipp-spiess) in [#13301](https://github.com/facebook/react/issues/13301))1244* Don't show the uncaught error addendum if `e.preventDefault()` was called ([@gaearon](https://github.com/gaearon) in [#13384](https://github.com/facebook/react/issues/13384))1245* Warn about rendering Generators ([@gaearon](https://github.com/gaearon) in [#13312](https://github.com/facebook/react/issues/13312))1246* Remove irrelevant suggestion of a legacy method from a warning ([@zx6658](https://github.com/zx6658) in [#13169](https://github.com/facebook/react/issues/13169))1247* Remove `unstable_deferredUpdates` in favor of `unstable_scheduleWork` from `schedule` ([@gaearon](https://github.com/gaearon) in [#13488](https://github.com/facebook/react/issues/13488))1248* Fix unstable asynchronous mode from doing unnecessary work when an update takes too long ([@acdlite](https://github.com/acdlite) in [#13503](https://github.com/facebook/react/issues/13503))12491250### React DOM Server12511252* Fix crash with nullish children when using `dangerouslySetInnerHtml` in a selected `<option>` ([@mridgway](https://github.com/mridgway) in [#13078](https://github.com/facebook/react/issues/13078))1253* Fix crash when `setTimeout` is missing ([@dustinsoftware](https://github.com/dustinsoftware) in [#13088](https://github.com/facebook/react/issues/13088))12541255### React Test Renderer and Test Utils12561257* Fix `this` in a functional component for shallow renderer to be `undefined` ([@koba04](https://github.com/koba04) in [#13144](https://github.com/facebook/react/issues/13144))1258* Deprecate a Jest-specific `ReactTestUtils.mockComponent()` helper ([@bvaughn](https://github.com/bvaughn) in [#13193](https://github.com/facebook/react/issues/13193))1259* Warn about `ReactDOM.createPortal` usage within the test renderer ([@bvaughn](https://github.com/bvaughn) in [#12895](https://github.com/facebook/react/issues/12895))1260* Improve a confusing error message ([@gaearon](https://github.com/gaearon) in [#13351](https://github.com/facebook/react/issues/13351))12611262### React ART12631264* Add support for DevTools ([@yunchancho](https://github.com/yunchancho) in [#13173](https://github.com/facebook/react/issues/13173))12651266### Schedule (Experimental)12671268* New package for cooperatively scheduling work in a browser environment. It's used by React internally, but its public API is not finalized yet. ([@flarnie](https://github.com/flarnie) in [#12624](https://github.com/facebook/react/pull/12624))12691270## 16.4.2 (August 1, 2018)12711272### React DOM Server12731274* Fix a [potential XSS vulnerability when the attacker controls an attribute name](https://reactjs.org/blog/2018/08/01/react-v-16-4-2.html) (`CVE-2018-6341`). This fix is available in the latest `react-dom@16.4.2`, as well as in previous affected minor versions: `react-dom@16.0.1`, `react-dom@16.1.2`, `react-dom@16.2.1`, and `react-dom@16.3.3`. ([@gaearon](https://github.com/gaearon) in [#13302](https://github.com/facebook/react/pull/13302))12751276* Fix a crash in the server renderer when an attribute is called `hasOwnProperty`. This fix is only available in `react-dom@16.4.2`. ([@gaearon](https://github.com/gaearon) in [#13303](https://github.com/facebook/react/pull/13303))12771278## 16.4.1 (June 13, 2018)12791280### React12811282* You can now assign `propTypes` to components returned by `React.ForwardRef`. ([@bvaughn](https://github.com/bvaughn) in [#12911](https://github.com/facebook/react/pull/12911))12831284### React DOM12851286* Fix a crash when the input `type` changes from some other types to `text`. ([@spirosikmd](https://github.com/spirosikmd) in [#12135](https://github.com/facebook/react/pull/12135))1287* Fix a crash in IE11 when restoring focus to an SVG element. ([@ThaddeusJiang](https://github.com/ThaddeusJiang) in [#12996](https://github.com/facebook/react/pull/12996))1288* Fix a range input not updating in some cases. ([@Illu](https://github.com/Illu) in [#12939](https://github.com/facebook/react/pull/12939))1289* Fix input validation triggering unnecessarily in Firefox. ([@nhunzaker](https://github.com/nhunzaker) in [#12925](https://github.com/facebook/react/pull/12925))1290* Fix an incorrect `event.target` value for the `onChange` event in IE9. ([@nhunzaker](https://github.com/nhunzaker) in [#12976](https://github.com/facebook/react/pull/12976))1291* Fix a false positive error when returning an empty `<React.Fragment />` from a component. ([@philipp-spiess](https://github.com/philipp-spiess) in [#12966](https://github.com/facebook/react/pull/12966))12921293### React DOM Server12941295* Fix an incorrect value being provided by new context API. ([@ericsoderberghp](https://github.com/ericsoderberghp) in [#12985](https://github.com/facebook/react/pull/12985), [@gaearon](https://github.com/gaearon) in [#13019](https://github.com/facebook/react/pull/13019))12961297### React Test Renderer12981299* Allow multiple root children in test renderer traversal API. ([@gaearon](https://github.com/gaearon) in [#13017](https://github.com/facebook/react/pull/13017))1300* Fix `getDerivedStateFromProps()` in the shallow renderer to not discard the pending state. ([@fatfisz](https://github.com/fatfisz) in [#13030](https://github.com/facebook/react/pull/13030))13011302## 16.4.0 (May 23, 2018)13031304### React13051306* Add a new [experimental](https://github.com/reactjs/rfcs/pull/51) `React.unstable_Profiler` component for measuring performance. ([@bvaughn](https://github.com/bvaughn) in [#12745](https://github.com/facebook/react/pull/12745))13071308### React DOM13091310* Add support for the Pointer Events specification. ([@philipp-spiess](https://github.com/philipp-spiess) in [#12507](https://github.com/facebook/react/pull/12507))1311* Properly call `getDerivedStateFromProps()` regardless of the reason for re-rendering. ([@acdlite](https://github.com/acdlite) in [#12600](https://github.com/facebook/react/pull/12600) and [#12802](https://github.com/facebook/react/pull/12802))1312* Fix a bug that prevented context propagation in some cases. ([@gaearon](https://github.com/gaearon) in [#12708](https://github.com/facebook/react/pull/12708))1313* Fix re-rendering of components using `forwardRef()` on a deeper `setState()`. ([@gaearon](https://github.com/gaearon) in [#12690](https://github.com/facebook/react/pull/12690))1314* Fix some attributes incorrectly getting removed from custom element nodes. ([@airamrguez](https://github.com/airamrguez) in [#12702](https://github.com/facebook/react/pull/12702))1315* Fix context providers to not bail out on children if there's a legacy context provider above. ([@gaearon](https://github.com/gaearon) in [#12586](https://github.com/facebook/react/pull/12586))1316* Add the ability to specify `propTypes` on a context provider component. ([@nicolevy](https://github.com/nicolevy) in [#12658](https://github.com/facebook/react/pull/12658))1317* Fix a false positive warning when using `react-lifecycles-compat` in `<StrictMode>`. ([@bvaughn](https://github.com/bvaughn) in [#12644](https://github.com/facebook/react/pull/12644))1318* Warn when the `forwardRef()` render function has `propTypes` or `defaultProps`. ([@bvaughn](https://github.com/bvaughn) in [#12644](https://github.com/facebook/react/pull/12644))1319* Improve how `forwardRef()` and context consumers are displayed in the component stack. ([@sophiebits](https://github.com/sophiebits) in [#12777](https://github.com/facebook/react/pull/12777))1320* Change internal event names. This can break third-party packages that rely on React internals in unsupported ways. ([@philipp-spiess](https://github.com/philipp-spiess) in [#12629](https://github.com/facebook/react/pull/12629))13211322### React Test Renderer13231324* Fix the `getDerivedStateFromProps()` support to match the new React DOM behavior. ([@koba04](https://github.com/koba04) in [#12676](https://github.com/facebook/react/pull/12676))1325* Fix a `testInstance.parent` crash when the parent is a fragment or another special node. ([@gaearon](https://github.com/gaearon) in [#12813](https://github.com/facebook/react/pull/12813))1326* `forwardRef()` components are now discoverable by the test renderer traversal methods. ([@gaearon](https://github.com/gaearon) in [#12725](https://github.com/facebook/react/pull/12725))1327* Shallow renderer now ignores `setState()` updaters that return `null` or `undefined`. ([@koba04](https://github.com/koba04) in [#12756](https://github.com/facebook/react/pull/12756))13281329### React ART13301331* Fix reading context provided from the tree managed by React DOM. ([@acdlite](https://github.com/acdlite) in [#12779](https://github.com/facebook/react/pull/12779))13321333### React Call Return (Experimental)13341335* This experiment was deleted because it was affecting the bundle size and the API wasn't good enough. It's likely to come back in the future in some other form. ([@gaearon](https://github.com/gaearon) in [#12820](https://github.com/facebook/react/pull/12820))13361337### React Reconciler (Experimental)13381339* The [new host config shape](https://github.com/facebook/react/blob/c601f7a64640290af85c9f0e33c78480656b46bc/packages/react-noop-renderer/src/createReactNoop.js#L82-L285) is flat and doesn't use nested objects. ([@gaearon](https://github.com/gaearon) in [#12792](https://github.com/facebook/react/pull/12792))13401341## 16.3.3 (August 1, 2018)13421343### React DOM Server13441345* Fix a [potential XSS vulnerability when the attacker controls an attribute name](https://reactjs.org/blog/2018/08/01/react-v-16-4-2.html) (`CVE-2018-6341`). This fix is available in the latest `react-dom@16.4.2`, as well as in previous affected minor versions: `react-dom@16.0.1`, `react-dom@16.1.2`, `react-dom@16.2.1`, and `react-dom@16.3.3`. ([@gaearon](https://github.com/gaearon) in [#13302](https://github.com/facebook/react/pull/13302))13461347## 16.3.2 (April 16, 2018)13481349### React13501351* Improve the error message when passing `null` or `undefined` to `React.cloneElement`. ([@nicolevy](https://github.com/nicolevy) in [#12534](https://github.com/facebook/react/pull/12534))13521353### React DOM13541355* Fix an IE crash in development when using `<StrictMode>`. ([@bvaughn](https://github.com/bvaughn) in [#12546](https://github.com/facebook/react/pull/12546))1356* Fix labels in User Timing measurements for new component types. ([@bvaughn](https://github.com/bvaughn) in [#12609](https://github.com/facebook/react/pull/12609))1357* Improve the warning about wrong component type casing. ([@nicolevy](https://github.com/nicolevy) in [#12533](https://github.com/facebook/react/pull/12533))1358* Improve general performance in development mode. ([@gaearon](https://github.com/gaearon) in [#12537](https://github.com/facebook/react/pull/12537))1359* Improve performance of the experimental `unstable_observedBits` API with nesting. ([@gaearon](https://github.com/gaearon) in [#12543](https://github.com/facebook/react/pull/12543))13601361### React Test Renderer13621363* Add a UMD build. ([@bvaughn](https://github.com/bvaughn) in [#12594](https://github.com/facebook/react/pull/12594))13641365## 16.3.1 (April 3, 2018)13661367### React13681369* Fix a false positive warning in IE11 when using `Fragment`. ([@heikkilamarko](https://github.com/heikkilamarko) in [#12504](https://github.com/facebook/react/pull/12504))1370* Prefix a private API. ([@Andarist](https://github.com/Andarist) in [#12501](https://github.com/facebook/react/pull/12501))1371* Improve the warning when calling `setState()` in constructor. ([@gaearon](https://github.com/gaearon) in [#12532](https://github.com/facebook/react/pull/12532))13721373### React DOM13741375* Fix `getDerivedStateFromProps()` not getting applied in some cases. ([@acdlite](https://github.com/acdlite) in [#12528](https://github.com/facebook/react/pull/12528))1376* Fix a performance regression in development mode. ([@gaearon](https://github.com/gaearon) in [#12510](https://github.com/facebook/react/pull/12510))1377* Fix error handling bugs in development mode. ([@gaearon](https://github.com/gaearon) and [@acdlite](https://github.com/acdlite) in [#12508](https://github.com/facebook/react/pull/12508))1378* Improve user timing API messages for profiling. ([@flarnie](https://github.com/flarnie) in [#12384](https://github.com/facebook/react/pull/12384))13791380### Create Subscription13811382* Set the package version to be in sync with React releases. ([@bvaughn](https://github.com/bvaughn) in [#12526](https://github.com/facebook/react/pull/12526))1383* Add a peer dependency on React 16.3+. ([@NMinhNguyen](https://github.com/NMinhNguyen) in [#12496](https://github.com/facebook/react/pull/12496))13841385## 16.3.0 (March 29, 2018)13861387### React13881389* Add a new officially supported context API. ([@acdlite](https://github.com/acdlite) in [#11818](https://github.com/facebook/react/pull/11818))1390* Add a new `React.createRef()` API as an ergonomic alternative to callback refs. ([@trueadm](https://github.com/trueadm) in [#12162](https://github.com/facebook/react/pull/12162))1391* Add a new `React.forwardRef()` API to let components forward their refs to a child. ([@bvaughn](https://github.com/bvaughn) in [#12346](https://github.com/facebook/react/pull/12346))1392* Fix a false positive warning in IE11 when using `React.Fragment`. ([@XaveScor](https://github.com/XaveScor) in [#11823](https://github.com/facebook/react/pull/11823))1393* Replace `React.unstable_AsyncComponent` with `React.unstable_AsyncMode`. ([@acdlite](https://github.com/acdlite) in [#12117](https://github.com/facebook/react/pull/12117))1394* Improve the error message when calling `setState()` on an unmounted component. ([@sophiebits](https://github.com/sophiebits) in [#12347](https://github.com/facebook/react/pull/12347))13951396### React DOM13971398* Add a new `getDerivedStateFromProps()` lifecycle and `UNSAFE_` aliases for the legacy lifecycles. ([@bvaughn](https://github.com/bvaughn) in [#12028](https://github.com/facebook/react/pull/12028))1399* Add a new `getSnapshotBeforeUpdate()` lifecycle. ([@bvaughn](https://github.com/bvaughn) in [#12404](https://github.com/facebook/react/pull/12404))1400* Add a new `<React.StrictMode>` wrapper to help prepare apps for async rendering. ([@bvaughn](https://github.com/bvaughn) in [#12083](https://github.com/facebook/react/pull/12083))1401* Add support for `onLoad` and `onError` events on the `<link>` tag. ([@roderickhsiao](https://github.com/roderickhsiao) in [#11825](https://github.com/facebook/react/pull/11825))1402* Add support for `noModule` boolean attribute on the `<script>` tag. ([@aweary](https://github.com/aweary) in [#11900](https://github.com/facebook/react/pull/11900))1403* Fix minor DOM input bugs in IE and Safari. ([@nhunzaker](https://github.com/nhunzaker) in [#11534](https://github.com/facebook/react/pull/11534))1404* Correctly detect Ctrl + Enter in `onKeyPress` in more browsers. ([@nstraub](https://github.com/nstraub) in [#10514](https://github.com/facebook/react/pull/10514))1405* Fix containing elements getting focused on SSR markup mismatch. ([@koba04](https://github.com/koba04) in [#11737](https://github.com/facebook/react/pull/11737))1406* Fix `value` and `defaultValue` to ignore Symbol values. ([@nhunzaker](https://github.com/nhunzaker) in [#11741](https://github.com/facebook/react/pull/11741))1407* Fix refs to class components not getting cleaned up when the attribute is removed. ([@bvaughn](https://github.com/bvaughn) in [#12178](https://github.com/facebook/react/pull/12178))1408* Fix an IE/Edge issue when rendering inputs into a different window. ([@M-ZubairAhmed](https://github.com/M-ZubairAhmed) in [#11870](https://github.com/facebook/react/pull/11870))1409* Throw with a meaningful message if the component runs after jsdom has been destroyed. ([@gaearon](https://github.com/gaearon) in [#11677](https://github.com/facebook/react/pull/11677))1410* Don't crash if there is a global variable called `opera` with a `null` value. [@alisherdavronov](https://github.com/alisherdavronov) in [#11854](https://github.com/facebook/react/pull/11854))1411* Don't check for old versions of Opera. ([@skiritsis](https://github.com/skiritsis) in [#11921](https://github.com/facebook/react/pull/11921))1412* Deduplicate warning messages about `<option selected>`. ([@watadarkstar](https://github.com/watadarkstar) in [#11821](https://github.com/facebook/react/pull/11821))1413* Deduplicate warning messages about invalid callback. ([@yenshih](https://github.com/yenshih) in [#11833](https://github.com/facebook/react/pull/11833))1414* Deprecate `ReactDOM.unstable_createPortal()` in favor of `ReactDOM.createPortal()`. ([@prometheansacrifice](https://github.com/prometheansacrifice) in [#11747](https://github.com/facebook/react/pull/11747))1415* Don't emit User Timing entries for context types. ([@abhaynikam](https://github.com/abhaynikam) in [#12250](https://github.com/facebook/react/pull/12250))1416* Improve the error message when context consumer child isn't a function. ([@raunofreiberg](https://github.com/raunofreiberg) in [#12267](https://github.com/facebook/react/pull/12267))1417* Improve the error message when adding a ref to a functional component. ([@skiritsis](https://github.com/skiritsis) in [#11782](https://github.com/facebook/react/pull/11782))14181419### React DOM Server14201421* Prevent an infinite loop when attempting to render portals with SSR. ([@gaearon](https://github.com/gaearon) in [#11709](https://github.com/facebook/react/pull/11709))1422* Warn if a class doesn't extend `React.Component`. ([@wyze](https://github.com/wyze) in [#11993](https://github.com/facebook/react/pull/11993))1423* Fix an issue with `this.state` of different components getting mixed up. ([@sophiebits](https://github.com/sophiebits) in [#12323](https://github.com/facebook/react/pull/12323))1424* Provide a better message when component type is undefined. ([@HeroProtagonist](https://github.com/HeroProtagonist) in [#11966](https://github.com/facebook/react/pull/11966))14251426### React Test Renderer14271428* Fix handling of fragments in `toTree()`. ([@maciej-ka](https://github.com/maciej-ka) in [#12107](https://github.com/facebook/react/pull/12107) and [@gaearon](https://github.com/gaearon) in [#12154](https://github.com/facebook/react/pull/12154))1429* Shallow renderer should assign state to `null` for components that don't set it. ([@jwbay](https://github.com/jwbay) in [#11965](https://github.com/facebook/react/pull/11965))1430* Shallow renderer should filter legacy context according to `contextTypes`. ([@koba04](https://github.com/koba04) in [#11922](https://github.com/facebook/react/pull/11922))1431* Add an unstable API for testing asynchronous rendering. ([@acdlite](https://github.com/acdlite) in [#12478](https://github.com/facebook/react/pull/12478))14321433### React Is (New)14341435* First release of the [new package](https://github.com/facebook/react/tree/main/packages/react-is) that libraries can use to detect different React node types. ([@bvaughn](https://github.com/bvaughn) in [#12199](https://github.com/facebook/react/pull/12199))1436* Add `ReactIs.isValidElementType()` to help higher-order components validate their inputs. ([@jamesreggio](https://github.com/jamesreggio) in [#12483](https://github.com/facebook/react/pull/12483))14371438### React Lifecycles Compat (New)14391440* First release of the [new package](https://github.com/reactjs/react-lifecycles-compat) to help library developers target multiple versions of React. ([@bvaughn](https://github.com/bvaughn) in [#12105](https://github.com/facebook/react/pull/12105))14411442### Create Subscription (New)14431444* First release of the [new package](https://github.com/facebook/react/tree/main/packages/create-subscription) to subscribe to external data sources safely for async rendering. ([@bvaughn](https://github.com/bvaughn) in [#12325](https://github.com/facebook/react/pull/12325))14451446### React Reconciler (Experimental)14471448* Expose `react-reconciler/persistent` for building renderers that use persistent data structures. ([@gaearon](https://github.com/gaearon) in [#12156](https://github.com/facebook/react/pull/12156))1449* Pass host context to `finalizeInitialChildren()`. ([@jquense](https://github.com/jquense) in [#11970](https://github.com/facebook/react/pull/11970))1450* Remove `useSyncScheduling` from the host config. ([@acdlite](https://github.com/acdlite) in [#11771](https://github.com/facebook/react/pull/11771))14511452### React Call Return (Experimental)14531454* Fix a crash on updates. ([@rmhartog](https://github.com/rmhartog) in [#11955](https://github.com/facebook/react/pull/11955))14551456## 16.2.1 (August 1, 2018)14571458### React DOM Server14591460* Fix a [potential XSS vulnerability when the attacker controls an attribute name](https://reactjs.org/blog/2018/08/01/react-v-16-4-2.html) (`CVE-2018-6341`). This fix is available in the latest `react-dom@16.4.2`, as well as in previous affected minor versions: `react-dom@16.0.1`, `react-dom@16.1.2`, `react-dom@16.2.1`, and `react-dom@16.3.3`. ([@gaearon](https://github.com/gaearon) in [#13302](https://github.com/facebook/react/pull/13302))14611462## 16.2.0 (November 28, 2017)14631464### React14651466* Add `Fragment` as named export to React. ([@clemmy](https://github.com/clemmy) in [#10783](https://github.com/facebook/react/pull/10783))1467* Support experimental Call/Return types in `React.Children` utilities. ([@MatteoVH](https://github.com/MatteoVH) in [#11422](https://github.com/facebook/react/pull/11422))14681469### React DOM14701471* Fix radio buttons not getting checked when using multiple lists of radios. ([@landvibe](https://github.com/landvibe) in [#11227](https://github.com/facebook/react/pull/11227))1472* Fix radio buttons not receiving the `onChange` event in some cases. ([@jquense](https://github.com/jquense) in [#11028](https://github.com/facebook/react/pull/11028))14731474### React Test Renderer14751476* Fix `setState()` callback firing too early when called from `componentWillMount`. ([@accordeiro](https://github.com/accordeiro) in [#11507](https://github.com/facebook/react/pull/11507))14771478### React Reconciler14791480* Expose `react-reconciler/reflection` with utilities useful to custom renderers. ([@rivenhk](https://github.com/rivenhk) in [#11683](https://github.com/facebook/react/pull/11683))14811482### Internal Changes14831484* Many tests were rewritten against the public API. Big thanks to [everyone who contributed](https://github.com/facebook/react/issues/11299)!14851486## 16.1.2 (August 1, 2018)14871488### React DOM Server14891490* Fix a [potential XSS vulnerability when the attacker controls an attribute name](https://reactjs.org/blog/2018/08/01/react-v-16-4-2.html) (`CVE-2018-6341`). This fix is available in the latest `react-dom@16.4.2`, as well as in previous affected minor versions: `react-dom@16.0.1`, `react-dom@16.1.2`, `react-dom@16.2.1`, and `react-dom@16.3.3`. ([@gaearon](https://github.com/gaearon) in [#13302](https://github.com/facebook/react/pull/13302))14911492## 16.1.1 (November 13, 2017)14931494### React14951496* Improve the warning about undefined component type. ([@selbekk](https://github.com/selbekk) in [#11505](https://github.com/facebook/react/pull/11505))14971498### React DOM14991500* Support string values for the `capture` attribute. ([@maxschmeling](https://github.com/maxschmeling) in [#11424](https://github.com/facebook/react/pull/11424))15011502### React DOM Server15031504* Don't freeze the `ReactDOMServer` public API. ([@travi](https://github.com/travi) in [#11531](https://github.com/facebook/react/pull/11531))1505* Don't emit `autoFocus={false}` attribute on the server. ([@gaearon](https://github.com/gaearon) in [#11543](https://github.com/facebook/react/pull/11543))15061507### React Reconciler15081509* Change the hydration API for better Flow typing. ([@sebmarkbage](https://github.com/sebmarkbage) in [#11493](https://github.com/facebook/react/pull/11493))15101511## 16.1.0 (November 9, 2017)15121513### Discontinuing Bower Releases15141515Starting with 16.1.0, we will no longer be publishing new releases on Bower. You can continue using Bower for old releases, or point your Bower configs to the [React UMD builds hosted on unpkg](https://reactjs.org/docs/installation.html#using-a-cdn) that mirror npm releases and will continue to be updated.15161517### All Packages15181519* Fix an accidental extra global variable in the UMD builds. ([@gaearon](https://github.com/gaearon) in [#10935](https://github.com/facebook/react/pull/10935))15201521### React15221523* Add support for portals in `React.Children` utilities. ([@MatteoVH](https://github.com/MatteoVH) in [#11378](https://github.com/facebook/react/pull/11378))1524* Warn when a class has a `render` method but doesn't extend a known base class. ([@sw-yx](https://github.com/sw-yx) in [#11168](https://github.com/facebook/react/pull/11168))1525* Improve the warning when accidentally returning an object from constructor. ([@deanbrophy](https://github.com/deanbrophy) in [#11395](https://github.com/facebook/react/pull/11395))15261527### React DOM15281529* Allow `on` as a custom attribute for AMP. ([@nuc](https://github.com/nuc) in [#11153](https://github.com/facebook/react/pull/11153))1530* Fix `onMouseEnter` and `onMouseLeave` firing on wrong elements. ([@gaearon](https://github.com/gaearon) in [#11164](https://github.com/facebook/react/pull/11164))1531* Fix `null` showing up in a warning instead of the component stack. ([@gaearon](https://github.com/gaearon) in [#10915](https://github.com/facebook/react/pull/10915))1532* Fix IE11 crash in development mode. ([@leidegre](https://github.com/leidegre) in [#10921](https://github.com/facebook/react/pull/10921))1533* Fix `tabIndex` not getting applied to SVG elements. ([@gaearon](https://github.com/gaearon) in [#11034](https://github.com/facebook/react/pull/11034))1534* Fix SVG children not getting cleaned up on `dangerouslySetInnerHTML` in IE. ([@OriR](https://github.com/OriR) in [#11108](https://github.com/facebook/react/pull/11108))1535* Fix false positive text mismatch warning caused by newline normalization. ([@gaearon](https://github.com/gaearon) in [#11119](https://github.com/facebook/react/pull/11119))1536* Fix `form.reset()` to respect `defaultValue` on uncontrolled `<select>`. ([@aweary](https://github.com/aweary) in [#11057](https://github.com/facebook/react/pull/11057))1537* Fix `<textarea>` placeholder not rendering on IE11. ([@gaearon](https://github.com/gaearon) in [#11177](https://github.com/facebook/react/pull/11177))1538* Fix a crash rendering into shadow root. ([@gaearon](https://github.com/gaearon) in [#11037](https://github.com/facebook/react/pull/11037))1539* Fix false positive warning about hydrating mixed case SVG tags. ([@gaearon](https://github.com/gaearon) in [#11174](https://github.com/facebook/react/pull/11174))1540* Suppress the new unknown tag warning for `<dialog>` element. ([@gaearon](https://github.com/gaearon) in [#11035](https://github.com/facebook/react/pull/11035))1541* Warn when defining a non-existent `componentDidReceiveProps` method. ([@iamtommcc](https://github.com/iamtommcc) in [#11479](https://github.com/facebook/react/pull/11479))1542* Warn about function child no more than once. ([@andreysaleba](https://github.com/andreysaleba) in [#11120](https://github.com/facebook/react/pull/11120))1543* Warn about nested updates no more than once. ([@anushreesubramani](https://github.com/anushreesubramani) in [#11113](https://github.com/facebook/react/pull/11113))1544* Deduplicate other warnings about updates. ([@anushreesubramani](https://github.com/anushreesubramani) in [#11216](https://github.com/facebook/react/pull/11216))1545* Include component stack into the warning about `contentEditable` and `children`. ([@Ethan-Arrowood](https://github.com/Ethan-Arrowood) in [#11208](https://github.com/facebook/react/pull/11208))1546* Improve the warning about booleans passed to event handlers. ([@NicBonetto](https://github.com/NicBonetto) in [#11308](https://github.com/facebook/react/pull/11308))1547* Improve the warning when a multiple `select` gets null `value`. ([@Hendeca](https://github.com/Hendeca) in [#11141](https://github.com/facebook/react/pull/11141))1548* Move link in the warning message to avoid redirect. ([@marciovicente](https://github.com/marciovicente) in [#11400](https://github.com/facebook/react/pull/11400))1549* Add a way to suppress the React DevTools installation prompt. ([@gaearon](https://github.com/gaearon) in [#11448](https://github.com/facebook/react/pull/11448))1550* Remove unused code. ([@gaearon](https://github.com/gaearon) in [#10802](https://github.com/facebook/react/pull/10802), [#10803](https://github.com/facebook/react/pull/10803))15511552### React DOM Server15531554* Add a new `suppressHydrationWarning` attribute for intentional client/server text mismatches. ([@sebmarkbage](https://github.com/sebmarkbage) in [#11126](https://github.com/facebook/react/pull/11126))1555* Fix markup generation when components return strings. ([@gaearon](https://github.com/gaearon) in [#11109](https://github.com/facebook/react/pull/11109))1556* Fix obscure error message when passing an invalid style value. ([@iamdustan](https://github.com/iamdustan) in [#11173](https://github.com/facebook/react/pull/11173))1557* Include the `autoFocus` attribute into SSR markup. ([@gaearon](https://github.com/gaearon) in [#11192](https://github.com/facebook/react/pull/11192))1558* Include the component stack into more warnings. ([@gaearon](https://github.com/gaearon) in [#11284](https://github.com/facebook/react/pull/11284))15591560### React Test Renderer and Test Utils15611562* Fix multiple `setState()` calls in `componentWillMount()` in shallow renderer. ([@Hypnosphi](https://github.com/Hypnosphi) in [#11167](https://github.com/facebook/react/pull/11167))1563* Fix shallow renderer to ignore `shouldComponentUpdate()` after `forceUpdate()`. ([@d4rky-pl](https://github.com/d4rky-pl) in [#11239](https://github.com/facebook/react/pull/11239) and [#11439](https://github.com/facebook/react/pull/11439))1564* Handle `forceUpdate()` and `React.PureComponent` correctly. ([@koba04](https://github.com/koba04) in [#11440](https://github.com/facebook/react/pull/11440))1565* Add back support for running in production mode. ([@gaearon](https://github.com/gaearon) in [#11112](https://github.com/facebook/react/pull/11112))1566* Add a missing `package.json` dependency. ([@gaearon](https://github.com/gaearon) in [#11340](https://github.com/facebook/react/pull/11340))15671568### React ART15691570* Add a missing `package.json` dependency. ([@gaearon](https://github.com/gaearon) in [#11341](https://github.com/facebook/react/pull/11341))1571* Expose `react-art/Circle`, `react-art/Rectangle`, and `react-art/Wedge`. ([@gaearon](https://github.com/gaearon) in [#11343](https://github.com/facebook/react/pull/11343))15721573### React Reconciler (Experimental)15741575* First release of the [new experimental package](https://github.com/facebook/react/blob/main/packages/react-reconciler/README.md) for creating custom renderers. ([@iamdustan](https://github.com/iamdustan) in [#10758](https://github.com/facebook/react/pull/10758))1576* Add support for React DevTools. ([@gaearon](https://github.com/gaearon) in [#11463](https://github.com/facebook/react/pull/11463))15771578### React Call Return (Experimental)15791580* First release of the [new experimental package](https://github.com/facebook/react/tree/main/packages/react-call-return) for parent-child communication. ([@gaearon](https://github.com/gaearon) in [#11364](https://github.com/facebook/react/pull/11364))15811582## 16.0.1 (August 1, 2018)15831584### React DOM Server15851586* Fix a [potential XSS vulnerability when the attacker controls an attribute name](https://reactjs.org/blog/2018/08/01/react-v-16-4-2.html) (`CVE-2018-6341`). This fix is available in the latest `react-dom@16.4.2`, as well as in previous affected minor versions: `react-dom@16.0.1`, `react-dom@16.1.2`, `react-dom@16.2.1`, and `react-dom@16.3.3`. ([@gaearon](https://github.com/gaearon) in [#13302](https://github.com/facebook/react/pull/13302))15871588## 16.0.0 (September 26, 2017)15891590### New JS Environment Requirements15911592 * React 16 depends on the collection types [Map](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Map) and [Set](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Set), as well as [requestAnimationFrame](https://developer.mozilla.org/en-US/docs/Web/API/window/requestAnimationFrame). If you support older browsers and devices which may not yet provide these natively (e.g. <IE11), [you may want to include a polyfill](https://gist.github.com/gaearon/9a4d54653ae9c50af6c54b4e0e56b583).15931594### New Features1595* Components can now return arrays and strings from `render`. (Docs coming soon!)1596* Improved error handling with introduction of "error boundaries". [Error boundaries](https://reactjs.org/blog/2017/07/26/error-handling-in-react-16.html) are React components that catch JavaScript errors anywhere in their child component tree, log those errors, and display a fallback UI instead of the component tree that crashed.1597* First-class support for declaratively rendering a subtree into another DOM node with `ReactDOM.createPortal()`. (Docs coming soon!)1598* Streaming mode for server side rendering is enabled with `ReactDOMServer.renderToNodeStream()` and `ReactDOMServer.renderToStaticNodeStream()`. ([@aickin](https://github.com/aickin) in [#10425](https://github.com/facebook/react/pull/10425), [#10044](https://github.com/facebook/react/pull/10044), [#10039](https://github.com/facebook/react/pull/10039), [#10024](https://github.com/facebook/react/pull/10024), [#9264](https://github.com/facebook/react/pull/9264), and others.)1599* [React DOM now allows passing non-standard attributes](https://reactjs.org/blog/2017/09/08/dom-attributes-in-react-16.html). ([@nhunzaker](https://github.com/nhunzaker) in [#10385](https://github.com/facebook/react/pull/10385), [10564](https://github.com/facebook/react/pull/10564), [#10495](https://github.com/facebook/react/pull/10495) and others)16001601### Breaking Changes1602- There are several changes to the behavior of scheduling and lifecycle methods:1603  * `ReactDOM.render()` and `ReactDOM.unstable_renderIntoContainer()` now return `null` if called from inside a lifecycle method.1604    * To work around this, you can either use [the new portal API](https://github.com/facebook/react/issues/10309#issuecomment-318433235) or [refs](https://github.com/facebook/react/issues/10309#issuecomment-318434635).1605  * Minor changes to `setState` behavior:1606    * Calling `setState` with null no longer triggers an update. This allows you to decide in an updater function if you want to re-render.1607    * Calling `setState` directly in render always causes an update. This was not previously the case. Regardless, you should not be calling `setState` from render.1608    * `setState` callback (second argument) now fires immediately after `componentDidMount` / `componentDidUpdate` instead of after all components have rendered.1609  * When replacing `<A />` with `<B />`,  `B.componentWillMount` now always happens before  `A.componentWillUnmount`. Previously, `A.componentWillUnmount` could fire first in some cases.1610  * Previously, changing the `ref` to a component would always detach the ref before that component's render is called. Now, we change the `ref` later, when applying the changes to the DOM.1611  * It is not safe to re-render into a container that was modified by something other than React. This worked previously in some cases but was never supported. We now emit a warning in this case. Instead you should clean up your component trees using `ReactDOM.unmountComponentAtNode`. [See this example.](https://github.com/facebook/react/issues/10294#issuecomment-318820987)1612  * `componentDidUpdate` lifecycle no longer receives `prevContext` param. ([@bvaughn](https://github.com/bvaughn) in [#8631](https://github.com/facebook/react/pull/8631))1613  * Non-unique keys may now cause children to be duplicated and/or omitted. Using non-unique keys is not (and has never been) supported, but previously it was a hard error.1614  * Shallow renderer no longer calls `componentDidUpdate()` because DOM refs are not available. This also makes it consistent with `componentDidMount()` (which does not get called in previous versions either).1615  * Shallow renderer does not implement `unstable_batchedUpdates()` anymore.1616  * `ReactDOM.unstable_batchedUpdates` now only takes one extra argument after the callback.1617- The names and paths to the single-file browser builds have changed to emphasize the difference between development and production builds. For example:1618  - `react/dist/react.js` → `react/umd/react.development.js`1619  - `react/dist/react.min.js` → `react/umd/react.production.min.js`1620  - `react-dom/dist/react-dom.js` → `react-dom/umd/react-dom.development.js`1621  - `react-dom/dist/react-dom.min.js` → `react-dom/umd/react-dom.production.min.js`1622* The server renderer has been completely rewritten, with some improvements:1623  * Server rendering does not use markup validation anymore, and instead tries its best to attach to existing DOM, warning about inconsistencies. It also doesn't use comments for empty components and data-reactid attributes on each node anymore.1624  * Hydrating a server rendered container now has an explicit API. Use `ReactDOM.hydrate` instead of `ReactDOM.render` if you're reviving server rendered HTML. Keep using `ReactDOM.render` if you're just doing client-side rendering.1625* When "unknown" props are passed to DOM components, for valid values, React will now render them in the DOM. [See this post for more details.](https://reactjs.org/blog/2017/09/08/dom-attributes-in-react-16.html) ([@nhunzaker](https://github.com/nhunzaker) in [#10385](https://github.com/facebook/react/pull/10385), [10564](https://github.com/facebook/react/pull/10564), [#10495](https://github.com/facebook/react/pull/10495) and others)1626* Errors in the render and lifecycle methods now unmount the component tree by default. To prevent this, add [error boundaries](https://reactjs.org/blog/2017/07/26/error-handling-in-react-16.html) to the appropriate places in the UI.16271628### Removed Deprecations16291630- There is no `react-with-addons.js` build anymore. All compatible addons are published separately on npm, and have single-file browser versions if you need them.1631- The deprecations introduced in 15.x have been removed from the core package. `React.createClass` is now available as create-react-class, `React.PropTypes` as prop-types, `React.DOM` as react-dom-factories, react-addons-test-utils as react-dom/test-utils, and shallow renderer as react-test-renderer/shallow. See [15.5.0](https://reactjs.org/blog/2017/04/07/react-v15.5.0.html) and [15.6.0](https://reactjs.org/blog/2017/06/13/react-v15.6.0.html) blog posts for instructions on migrating code and automated codemods.16321633## 15.7.0 (October 14, 2020)16341635### React16361637* Backport support for the [new JSX transform](https://reactjs.org/blog/2020/09/22/introducing-the-new-jsx-transform.html) to 15.x. ([@lunaruan](https://github.com/lunaruan) in [#18299](https://github.com/facebook/react/pull/18299) and [@gaearon](https://github.com/gaearon) in [#20024](https://github.com/facebook/react/pull/20024))16381639## 15.6.2 (September 25, 2017)16401641### All Packages1642* Switch from BSD + Patents to MIT license16431644### React DOM16451646* Fix a bug where modifying `document.documentMode` would trigger IE detection in other browsers, breaking change events. ([@aweary](https://github.com/aweary) in [#10032](https://github.com/facebook/react/pull/10032))1647* CSS Columns are treated as unitless numbers. ([@aweary](https://github.com/aweary) in [#10115](https://github.com/facebook/react/pull/10115))1648* Fix bug in QtWebKit when wrapping synthetic events in proxies. ([@walrusfruitcake](https://github.com/walrusfruitcake) in [#10115](https://github.com/facebook/react/pull/10011))1649* Prevent event handlers from receiving extra argument in development. ([@aweary](https://github.com/aweary) in [#10115](https://github.com/facebook/react/pull/8363))1650* Fix cases where `onChange` would not fire with `defaultChecked` on radio inputs. ([@jquense](https://github.com/jquense) in [#10156](https://github.com/facebook/react/pull/10156))1651* Add support for `controlList` attribute to allowed DOM properties ([@nhunzaker](https://github.com/nhunzaker) in [#9940](https://github.com/facebook/react/pull/9940))1652* Fix a bug where creating an element with a ref in a constructor did not throw an error in development. ([@iansu](https://github.com/iansu) in [#10025](https://github.com/facebook/react/pull/10025))16531654## 15.6.1 (June 14, 2017)16551656### React DOM16571658* Fix a crash on iOS Safari. ([@jquense](https://github.com/jquense) in [#9960](https://github.com/facebook/react/pull/9960))1659* Don't add `px` to custom CSS property values. ([@TrySound](https://github.com/TrySound) in [#9966](https://github.com/facebook/react/pull/9966))16601661## 15.6.0 (June 13, 2017)16621663### React16641665* Downgrade deprecation warnings to use `console.warn` instead of `console.error`. ([@flarnie](https://github.com/flarnie) in [#9753](https://github.com/facebook/react/pull/9753))1666* Add a deprecation warning for `React.createClass`. Points users to `create-react-class` instead. ([@flarnie](https://github.com/flarnie) in [#9771](https://github.com/facebook/react/pull/9771))1667* Add deprecation warnings and separate module for `React.DOM` factory helpers. ([@nhunzaker](https://github.com/nhunzaker) in [#8356](https://github.com/facebook/react/pull/8356))1668* Warn for deprecation of `React.createMixin` helper, which was never used. ([@aweary](https://github.com/aweary) in [#8853](https://github.com/facebook/react/pull/8853))16691670### React DOM16711672* Add support for CSS variables in `style` attribute. ([@aweary](https://github.com/aweary) in [#9302](https://github.com/facebook/react/pull/9302))1673* Add support for CSS Grid style properties. ([@ericsakmar](https://github.com/ericsakmar) in [#9185](https://github.com/facebook/react/pull/9185))1674* Fix bug where inputs mutated value on type conversion. ([@nhunzaker](https://github.com/mhunzaker) in [#9806](https://github.com/facebook/react/pull/9806))1675* Fix issues with `onChange` not firing properly for some inputs. ([@jquense](https://github.com/jquense) in [#8575](https://github.com/facebook/react/pull/8575))1676* Fix bug where controlled number input mistakenly allowed period. ([@nhunzaker](https://github.com/nhunzaker) in [#9584](https://github.com/facebook/react/pull/9584))1677* Fix bug where performance entries were being cleared. ([@chrisui](https://github.com/chrisui) in [#9451](https://github.com/facebook/react/pull/9451))16781679### React Addons16801681* Fix AMD support for addons depending on `react`. ([@flarnie](https://github.com/flarnie) in [#9919](https://github.com/facebook/react/issues/9919))1682* Fix `isMounted()` to return `true` in `componentWillUnmount`. ([@mridgway](https://github.com/mridgway) in [#9638](https://github.com/facebook/react/issues/9638))1683* Fix `react-addons-update` to not depend on native `Object.assign`. ([@gaearon](https://github.com/gaearon) in [#9937](https://github.com/facebook/react/pull/9937))1684* Remove broken Google Closure Compiler annotation from `create-react-class`. ([@gaearon](https://github.com/gaearon) in [#9933](https://github.com/facebook/react/pull/9933))1685* Remove unnecessary dependency from `react-linked-input`. ([@gaearon](https://github.com/gaearon) in [#9766](https://github.com/facebook/react/pull/9766))1686* Point `react-addons-(css-)transition-group` to the new package. ([@gaearon](https://github.com/gaearon) in [#9937](https://github.com/facebook/react/pull/9937))16871688## 15.5.4 (April 11, 2017)16891690### React Addons1691* **Critical Bugfix:** Update the version of `prop-types` to fix critical bug.  ([@gaearon](https://github.com/gaearon) in [545c87f](https://github.com/facebook/react/commit/545c87fdc348f82eb0c3830bef715ed180785390))1692* Fix `react-addons-create-fragment` package to include `loose-envify` transform for Browserify users. ([@mridgway](https://github.com/mridgway) in [#9642](https://github.com/facebook/react/pull/9642))16931694### React Test Renderer1695* Fix compatibility with Enzyme by exposing `batchedUpdates` on shallow renderer. ([@gaearon](https://github.com/gaearon) in [9382](https://github.com/facebook/react/commit/69933e25c37cf5453a9ef132177241203ee8d2fd))16961697## 15.5.3 (April 7, 2017)16981699**Note: this release has a critical issue and was deprecated. Please update to 15.5.4 or higher.**17001701### React Addons1702* Fix `react-addons-create-fragment` package to export correct thing. ([@gaearon](https://github.com/gaearon) in [#9385](https://github.com/facebook/react/pull/9383))1703* Fix `create-react-class` package to include `loose-envify` transform for Browserify users. ([@mridgway](https://github.com/mridgway) in [#9642](https://github.com/facebook/react/pull/9642))17041705## 15.5.2 (April 7, 2017)17061707**Note: this release has a critical issue and was deprecated. Please update to 15.5.4 or higher.**17081709### React Addons1710* Fix the production single-file builds to not include the development code. ([@gaearon](https://github.com/gaearon) in [#9385](https://github.com/facebook/react/pull/9383))1711* Apply better minification to production single-file builds. ([@gaearon](https://github.com/gaearon) in [#9385](https://github.com/facebook/react/pull/9383))1712* Add missing and remove unnecessary dependencies to packages. ([@gaearon](https://github.com/gaearon) in [#9385](https://github.com/facebook/react/pull/9383))17131714## 15.5.1 (April 7, 2017)17151716**Note: this release has a critical issue and was deprecated. Please update to 15.5.4 or higher.**17171718### React1719* Fix erroneous PropTypes access warning. ([@acdlite](https://github.com/acdlite) in ([ec97ebb](https://github.com/facebook/react/commit/ec97ebbe7f15b58ae2f1323df39d06f119873344))17201721## 15.5.0 (April 7, 2017)17221723**Note: this release has a critical issue and was deprecated. Please update to 15.5.4 or higher.**17241725### React1726* <s>Added a deprecation warning for `React.createClass`. Points users to create-react-class instead. ([@acdlite](https://github.com/acdlite) in [#d9a4fa4](https://github.com/facebook/react/commit/d9a4fa4f51c6da895e1655f32255cf72c0fe620e))</s>1727* Added a deprecation warning for `React.PropTypes`. Points users to prop-types instead. ([@acdlite](https://github.com/acdlite) in [#043845c](https://github.com/facebook/react/commit/043845ce75ea0812286bbbd9d34994bb7e01eb28))1728* Fixed an issue when using `ReactDOM` together with `ReactDOMServer`. ([@wacii](https://github.com/wacii) in [#9005](https://github.com/facebook/react/pull/9005))1729* Fixed issue with Closure Compiler. ([@anmonteiro](https://github.com/anmonteiro) in [#8895](https://github.com/facebook/react/pull/8895))1730* Another fix for Closure Compiler. ([@Shastel](https://github.com/Shastel) in [#8882](https://github.com/facebook/react/pull/8882))1731* Added component stack info to invalid element type warning. ([@n3tr](https://github.com/n3tr) in [#8495](https://github.com/facebook/react/pull/8495))17321733### React DOM1734* Fixed Chrome bug when backspacing in number inputs. ([@nhunzaker](https://github.com/nhunzaker) in [#7359](https://github.com/facebook/react/pull/7359))1735* Added `react-dom/test-utils`, which exports the React Test Utils. ([@bvaughn](https://github.com/bvaughn))17361737### React Test Renderer1738* Fixed bug where `componentWillUnmount` was not called for children. ([@gre](https://github.com/gre) in [#8512](https://github.com/facebook/react/pull/8512))1739* Added `react-test-renderer/shallow`, which exports the shallow renderer. ([@bvaughn](https://github.com/bvaughn))17401741### React Addons1742* Last release for addons; they will no longer be actively maintained.1743* Removed `peerDependencies` so that addons continue to work indefinitely. ([@acdlite](https://github.com/acdlite) and [@bvaughn](https://github.com/bvaughn) in [8a06cd7](https://github.com/facebook/react/commit/8a06cd7a786822fce229197cac8125a551e8abfa) and [67a8db3](https://github.com/facebook/react/commit/67a8db3650d724a51e70be130e9008806402678a))1744* Updated to remove references to `React.createClass` and `React.PropTypes` ([@acdlite](https://github.com/acdlite) in [12a96b9](https://github.com/facebook/react/commit/12a96b94823d6b6de6b1ac13bd576864abd50175))1745* `react-addons-test-utils` is deprecated. Use `react-dom/test-utils` and `react-test-renderer/shallow` instead. ([@bvaughn](https://github.com/bvaughn))17461747## 15.4.2 (January 6, 2017)17481749### React1750* Fixed build issues with the Brunch bundler. ([@gaearon](https://github.com/gaearon) in [#8686](https://github.com/facebook/react/pull/8686))1751* Improved error messages for invalid element types. ([@sophiebits](https://github.com/sophiebits) in [#8612](https://github.com/facebook/react/pull/8612))1752* Removed a warning about `getInitialState` when `this.state` is set. ([@bvaughn](https://github.com/bvaughn) in [#8594](https://github.com/facebook/react/pull/8594))1753* Removed some dead code. ([@diegomura](https://github.com/diegomura) in [#8050](https://github.com/facebook/react/pull/8050), [@dfrownfelter](https://github.com/dfrownfelter) in [#8597](https://github.com/facebook/react/pull/8597))17541755### React DOM1756* Fixed a decimal point issue on uncontrolled number inputs. ([@nhunzaker](https://github.com/nhunzaker) in [#7750](https://github.com/facebook/react/pull/7750))1757* Fixed rendering of textarea placeholder in IE11. ([@aweary](https://github.com/aweary) in [#8020](https://github.com/facebook/react/pull/8020))1758* Worked around a script engine bug in IE9. ([@eoin](https://github.com/eoin) in [#8018](https://github.com/facebook/react/pull/8018))17591760### React Addons1761* Fixed build issues in RequireJS and SystemJS environments. ([@gaearon](https://github.com/gaearon) in [#8686](https://github.com/facebook/react/pull/8686))1762* Added missing package dependencies. ([@kweiberth](https://github.com/kweiberth) in [#8467](https://github.com/facebook/react/pull/8467))17631764## 15.4.1 (November 22, 2016)17651766### React1767* Restructure variable assignment to work around a Rollup bug ([@gaearon](https://github.com/gaearon) in [#8384](https://github.com/facebook/react/pull/8384))17681769### React DOM1770* Fixed event handling on disabled button elements ([@sophiebits](https://github.com/sophiebits) in [#8387](https://github.com/facebook/react/pull/8387))1771* Fixed compatibility of browser build with AMD environments ([@zpao](https://github.com/zpao) in [#8374](https://github.com/facebook/react/pull/8374))17721773## 15.4.0 (November 16, 2016)17741775### React1776* React package and browser build no longer "secretly" includes React DOM. ([@sebmarkbage](https://github.com/sebmarkbage) in [#7164](https://github.com/facebook/react/pull/7164) and [#7168](https://github.com/facebook/react/pull/7168))1777* Required PropTypes now fail with specific messages for null and undefined. ([@chenglou](https://github.com/chenglou) in [#7291](https://github.com/facebook/react/pull/7291))1778* Improved development performance by freezing children instead of copying. ([@keyanzhang](https://github.com/keyanzhang) in [#7455](https://github.com/facebook/react/pull/7455))17791780### React DOM1781* Fixed occasional test failures when React DOM is used together with shallow renderer. ([@goatslacker](https://github.com/goatslacker) in [#8097](https://github.com/facebook/react/pull/8097))1782* Added a warning for invalid `aria-` attributes. ([@jessebeach](https://github.com/jessebeach) in [#7744](https://github.com/facebook/react/pull/7744))1783* Added a warning for using `autofocus` rather than `autoFocus`. ([@hkal](https://github.com/hkal) in [#7694](https://github.com/facebook/react/pull/7694))1784* Removed an unnecessary warning about polyfilling `String.prototype.split`. ([@nhunzaker](https://github.com/nhunzaker) in [#7629](https://github.com/facebook/react/pull/7629))1785* Clarified the warning about not calling PropTypes manually. ([@jedwards1211](https://github.com/jedwards1211) in [#7777](https://github.com/facebook/react/pull/7777))1786* The unstable `batchedUpdates` API now passes the wrapped function's return value through. ([@bgnorlov](https://github.com/bgnorlov) in [#7444](https://github.com/facebook/react/pull/7444))1787* Fixed a bug with updating text in IE 8. ([@mnpenner](https://github.com/mnpenner) in [#7832](https://github.com/facebook/react/pull/7832))17881789### React Perf1790* When ReactPerf is started, you can now view the relative time spent in components as a chart in Chrome Timeline. ([@gaearon](https://github.com/gaearon) in [#7549](https://github.com/facebook/react/pull/7549))17911792### React Test Utils1793* If you call `Simulate.click()` on a `<input disabled onClick={foo} />` then `foo` will get called whereas it didn't before. ([@nhunzaker](https://github.com/nhunzaker) in [#7642](https://github.com/facebook/react/pull/7642))17941795### React Test Renderer1796* Due to packaging changes, it no longer crashes when imported together with React DOM in the same file. ([@sebmarkbage](https://github.com/sebmarkbage) in [#7164](https://github.com/facebook/react/pull/7164) and [#7168](https://github.com/facebook/react/pull/7168))1797* `ReactTestRenderer.create()` now accepts `{createNodeMock: element => mock}` as an optional argument so you can mock refs with snapshot testing. ([@Aweary](https://github.com/Aweary) in [#7649](https://github.com/facebook/react/pull/7649), [#8261](https://github.com/facebook/react/pull/8261))179817991800## 15.3.2 (September 19, 2016)18011802### React1803- Remove plain object warning from React.createElement & React.cloneElement. ([@spudly](https://github.com/spudly) in [#7724](https://github.com/facebook/react/pull/7724))18041805### React DOM1806- Add `playsInline` to supported HTML attributes. ([@reaperhulk](https://github.com/reaperhulk) in [#7519](https://github.com/facebook/react/pull/7519))1807- Add `as` to supported HTML attributes. ([@kevinslin](https://github.com/kevinslin) in [#7582](https://github.com/facebook/react/pull/7582))1808- Improve DOM nesting validation warning about whitespace. ([@sophiebits](https://github.com/sophiebits) in [#7515](https://github.com/facebook/react/pull/7515))1809- Avoid "Member not found" exception in IE10 when calling `preventDefault()` in Synthetic Events. ([@g-palmer](https://github.com/g-palmer) in [#7411](https://github.com/facebook/react/pull/7411))1810- Fix memory leak in `onSelect` implementation. ([@AgtLucas](https://github.com/AgtLucas) in [#7533](https://github.com/facebook/react/pull/7533))1811- Improve robustness of `document.documentMode` checks to handle Google Tag Manager. ([@SchleyB](https://github.com/SchleyB) in [#7594](https://github.com/facebook/react/pull/7594))1812- Add more cases to controlled inputs warning. ([@marcin-mazurek](https://github.com/marcin-mazurek) in [#7544](https://github.com/facebook/react/pull/7544))1813- Handle case of popup blockers overriding `document.createEvent`. ([@Andarist](https://github.com/Andarist) in [#7621](https://github.com/facebook/react/pull/7621))1814- Fix issue with `dangerouslySetInnerHTML` and SVG in Internet Explorer. ([@zpao](https://github.com/zpao) in [#7618](https://github.com/facebook/react/pull/7618))1815- Improve handling of Japanese IME on Internet Explorer. ([@msmania](https://github.com/msmania) in [#7107](https://github.com/facebook/react/pull/7107))18161817### React Test Renderer1818- Support error boundaries. ([@millermedeiros](https://github.com/millermedeiros) in [#7558](https://github.com/facebook/react/pull/7558), [#7569](https://github.com/facebook/react/pull/7569), [#7619](https://github.com/facebook/react/pull/7619))1819- Skip null ref warning. ([@Aweary](https://github.com/Aweary) in [#7658](https://github.com/facebook/react/pull/7658))18201821### React Perf Add-on1822- Ensure lifecycle timers are stopped on errors. ([@gaearon](https://github.com/gaearon) in [#7548](https://github.com/facebook/react/pull/7548))182318241825## 15.3.1 (August 19, 2016)18261827### React18281829- Improve performance of development builds in various ways. ([@gaearon](https://github.com/gaearon) in [#7461](https://github.com/facebook/react/pull/7461), [#7463](https://github.com/facebook/react/pull/7463), [#7483](https://github.com/facebook/react/pull/7483), [#7488](https://github.com/facebook/react/pull/7488), [#7491](https://github.com/facebook/react/pull/7491), [#7510](https://github.com/facebook/react/pull/7510))1830- Cleanup internal hooks to improve performance of development builds. ([@gaearon](https://github.com/gaearon) in [#7464](https://github.com/facebook/react/pull/7464), [#7472](https://github.com/facebook/react/pull/7472), [#7481](https://github.com/facebook/react/pull/7481), [#7496](https://github.com/facebook/react/pull/7496))1831- Upgrade fbjs to pick up another performance improvement from [@gaearon](https://github.com/gaearon) for development builds. ([@zpao](https://github.com/zpao) in [#7532](https://github.com/facebook/react/pull/7532))1832- Improve startup time of React in Node. ([@zertosh](https://github.com/zertosh) in [#7493](https://github.com/facebook/react/pull/7493))1833- Improve error message of `React.Children.only`. ([@sophiebits](https://github.com/sophiebits) in [#7514](https://github.com/facebook/react/pull/7514))18341835### React DOM1836- Avoid `<input>` validation warning from browsers when changing `type`. ([@nhunzaker](https://github.com/nhunzaker) in [#7333](https://github.com/facebook/react/pull/7333))1837- Avoid "Member not found" exception in IE10 when calling `stopPropagation()` in Synthetic Events. ([@nhunzaker](https://github.com/nhunzaker) in [#7343](https://github.com/facebook/react/pull/7343))1838- Fix issue resulting in inability to update some `<input>` elements in mobile browsers. ([@keyanzhang](https://github.com/keyanzhang) in [#7397](https://github.com/facebook/react/pull/7397))1839- Fix memory leak in server rendering. ([@keyanzhang](https://github.com/keyanzhang) in [#7410](https://github.com/facebook/react/pull/7410))1840- Fix issue resulting in `<input type="range">` values not updating when changing `min` or `max`. ([@troydemonbreun](https://github.com/troydemonbreun) in [#7486](https://github.com/facebook/react/pull/7486))1841- Add new warning for rare case of attempting to unmount a container owned by a different copy of React. ([@ventuno](https://github.com/ventuno) in [#7456](https://github.com/facebook/react/pull/7456))18421843### React Test Renderer1844- Fix ReactTestInstance::toJSON() with empty top-level components. ([@Morhaus](https://github.com/Morhaus) in [#7523](https://github.com/facebook/react/pull/7523))18451846### React Native Renderer1847- Change `trackedTouchCount` invariant into a console.error for better reliability. ([@yungsters](https://github.com/yungsters) in [#7400](https://github.com/facebook/react/pull/7400))184818491850## 15.3.0 (July 29, 2016)18511852### React1853- Add `React.PureComponent` - a new base class to extend, replacing `react-addons-pure-render-mixin` now that mixins don't work with ES2015 classes. ([@sophiebits](https://github.com/sophiebits) in [#7195](https://github.com/facebook/react/pull/7195))1854- Add new warning when modifying `this.props.children`. ([@jimfb](https://github.com/jimfb) in [#7001](https://github.com/facebook/react/pull/7001))1855- Fixed issue with ref resolution order. ([@gaearon](https://github.com/gaearon) in [#7101](https://github.com/facebook/react/pull/7101))1856- Warn when mixin is undefined. ([@swaroopsm](https://github.com/swaroopsm) in [#6158](https://github.com/facebook/react/pull/6158))1857- Downgrade "unexpected batch number" invariant to a warning. ([@sophiebits](https://github.com/sophiebits) in [#7133](https://github.com/facebook/react/pull/7133))1858- Validate arguments to `oneOf` and `oneOfType` PropTypes sooner. ([@troydemonbreun](https://github.com/troydemonbreun) in [#6316](https://github.com/facebook/react/pull/6316))1859- Warn when calling PropTypes directly. ([@Aweary](https://github.com/Aweary) in [#7132](https://github.com/facebook/react/pull/7132), [#7194](https://github.com/facebook/react/pull/7194))1860- Improve warning when using Maps as children. ([@keyanzhang](https://github.com/keyanzhang) in [#7260](https://github.com/facebook/react/pull/7260))1861- Add additional type information to the `PropTypes.element` warning. ([@alexzherdev](https://github.com/alexzherdev) in [#7319](https://github.com/facebook/react/pull/7319))1862- Improve component identification in no-op `setState` warning. ([@keyanzhang](https://github.com/keyanzhang) in [#7326](https://github.com/facebook/react/pull/7326))18631864### React DOM1865- Fix issue with nested server rendering. ([@Aweary](https://github.com/Aweary) in [#7033](https://github.com/facebook/react/pull/7033))1866- Add `xmlns`, `xmlnsXlink` to supported SVG attributes. ([@salzhrani](https://github.com/salzhrani) in [#6471](https://github.com/facebook/react/pull/6471))1867- Add `referrerPolicy` to supported HTML attributes. ([@Aweary](https://github.com/Aweary) in [#7274](https://github.com/facebook/react/pull/7274))1868- Fix issue resulting in `<input type="range">` initial value being rounded. ([@troydemonbreun](https://github.com/troydemonbreun) in [#7251](https://github.com/facebook/react/pull/7251))18691870### React Test Renderer1871- Initial public release of package allowing more focused testing. Install with `npm install react-test-renderer`. ([@sophiebits](https://github.com/sophiebits) in [#6944](https://github.com/facebook/react/pull/6944), [#7258](https://github.com/facebook/react/pull/7258), [@iamdustan](https://github.com/iamdustan) in [#7362](https://github.com/facebook/react/pull/7362))18721873### React Perf Add-on1874- Fix issue resulting in excessive warnings when encountering an internal measurement error. ([@sassanh](https://github.com/sassanh) in [#7299](https://github.com/facebook/react/pull/7299))18751876### React TestUtils Add-on1877- Implement `type` property on for events created via `TestUtils.Simulate.*`. ([@yaycmyk](https://github.com/yaycmyk) in [#6154](https://github.com/facebook/react/pull/6154))1878- Fix crash when running TestUtils with the production build of React. ([@gaearon](https://github.com/gaearon) in [#7246](https://github.com/facebook/react/pull/7246))187918801881## 15.2.1 (July 8, 2016)18821883### React1884- Fix errant warning about missing React element. ([@gaearon](https://github.com/gaearon) in [#7193](https://github.com/facebook/react/pull/7193))1885- Better removal of dev-only code, leading to a small reduction in the minified production bundle size. ([@gaearon](https://github.com/gaearon) in [#7188](https://github.com/facebook/react/pull/7188), [#7189](https://github.com/facebook/react/pull/7189))18861887### React DOM1888- Add stack trace to null input value warning. ([@jimfb](https://github.com/jimfb) in [#7040](https://github.com/facebook/react/pull/7040))1889- Fix webcomponents example. ([@jalexanderfox](https://github.com/jalexanderfox) in [#7057](https://github.com/facebook/react/pull/7057))1890- Fix `unstable_renderSubtreeIntoContainer` so that context properly updates when linked to state. ([@gaearon](https://github.com/gaearon) in [#7125](https://github.com/facebook/react/pull/7125))1891- Improve invariant wording for void elements. ([@starkch](https://github.com/starkch) in [#7066](https://github.com/facebook/react/pull/7066))1892- Ensure no errors are thrown due to event handlers in server rendering. ([@rricard](https://github.com/rricard) in [#7127](https://github.com/facebook/react/pull/7127))1893- Fix regression resulting in `value`-less submit and reset inputs removing the browser-default text. ([@zpao](https://github.com/zpao) in [#7197](https://github.com/facebook/react/pull/7197))1894- Fix regression resulting in empty `name` attribute being added to inputs when not provided. ([@okonet](https://github.com/okonet) in [#7199](https://github.com/facebook/react/pull/7199))1895- Fix issue with nested server rendering. ([@Aweary](https://github.com/Aweary) in [#7033](https://github.com/facebook/react/pull/7033))18961897### React Perf Add-on1898- Make `ReactPerf.start()` work properly during lifecycle methods. ([@gaearon](https://github.com/gaearon) in [#7208](https://github.com/facebook/react/pull/7208)).18991900### React CSSTransitionGroup Add-on1901- Fix issue resulting in spurious unknown property warnings. ([@batusai513](https://github.com/batusai513) in [#7165](https://github.com/facebook/react/pull/7165))19021903### React Native Renderer1904- Improve error handling in cross-platform touch event handling. ([@yungsters](https://github.com/yungsters) in [#7143](https://github.com/facebook/react/pull/7143))190519061907## 15.2.0 (July 1, 2016)19081909### React1910- Add error codes to production invariants, with links to the view the full error text. ([@keyanzhang](https://github.com/keyanzhang) in [#6948](https://github.com/facebook/react/pull/6948))1911- Include component stack information in PropType validation warnings. ([@troydemonbreun](https://github.com/troydemonbreun) in [#6398](https://github.com/facebook/react/pull/6398), [@sophiebits](https://github.com/sophiebits) in [#6771](https://github.com/facebook/react/pull/6771))1912- Include component stack information in key warnings. ([@keyanzhang](https://github.com/keyanzhang) in [#6799](https://github.com/facebook/react/pull/6799))1913- Stop validating props at mount time, only validate at element creation. ([@keyanzhang](https://github.com/keyanzhang) in [#6824](https://github.com/facebook/react/pull/6824))1914- New invariant providing actionable error in missing instance case. ([@yungsters](https://github.com/yungsters) in [#6990](https://github.com/facebook/react/pull/6990))1915- Add `React.PropTypes.symbol` to support ES2015 Symbols as props. ([@puradox](https://github.com/puradox) in [#6377](https://github.com/facebook/react/pull/6377))1916- Fix incorrect coercion of ref or key that are undefined in development ([@gaearon](https://github.com/gaearon) in [#6880](https://github.com/facebook/react/pull/6880))1917- Fix a false positive when passing other element’s props to cloneElement ([@ericmatthys](https://github.com/ericmatthys) in [#6268](https://github.com/facebook/react/pull/6268))1918- Warn if you attempt to define `childContextTypes` on a functional component ([@Aweary](https://github.com/Aweary) in [#6933](https://github.com/facebook/react/pull/6933))19191920### React DOM1921- Add warning for unknown properties on DOM elements. ([@jimfb](https://github.com/jimfb) in [#6800](https://github.com/facebook/react/pull/6800), [@gm758](https://github.com/gm758) in [#7152](https://github.com/facebook/react/pull/7152))1922- Properly remove attributes from custom elements. ([@grassator](https://github.com/grassator) in [#6748](https://github.com/facebook/react/pull/6748))1923- Fix invalid unicode escape in attribute name regular expression. ([@nbjahan](https://github.com/nbjahan) in [#6772](https://github.com/facebook/react/pull/6772))1924- Add `onLoad` handling to `<link>` element. ([@roderickhsiao](https://github.com/roderickhsiao) in [#6815](https://github.com/facebook/react/pull/6815))1925- Add `onError` handling to `<source>` element. ([@wadahiro](https://github.com/wadahiro) in [#6941](https://github.com/facebook/react/pull/6941))1926- Handle `value` and `defaultValue` more accurately in the DOM. ([@jimfb](https://github.com/jimfb) in [#6406](https://github.com/facebook/react/pull/6406))1927- Fix events issue in environments with mutated `Object.prototype`. ([@Weizenlol](https://github.com/Weizenlol) in [#6886](https://github.com/facebook/react/pull/6886))1928- Fix issue where `is="null"` ended up in the DOM in Firefox. ([@darobin](https://github.com/darobin) in [#6896](https://github.com/facebook/react/pull/6896))1929- Improved performance of text escaping by using [escape-html](https://github.com/component/escape-html). ([@aickin](https://github.com/aickin) in [#6862](https://github.com/facebook/react/pull/6862))1930- Fix issue with `dangerouslySetInnerHTML` and SVG in Internet Explorer. ([@joshhunt](https://github.com/joshhunt) in [#6982](https://github.com/facebook/react/pull/6982))1931- Fix issue with `<textarea>` placeholders. ([@jimfb](https://github.com/jimfb) in [#7002](https://github.com/facebook/react/pull/7002))1932- Fix controlled vs uncontrolled detection of `<input type="radio"/>`. ([@jimfb](https://github.com/jimfb) in [#7003](https://github.com/facebook/react/pull/7003))1933- Improve performance of updating text content. ([@trueadm](https://github.com/trueadm) in [#7005](https://github.com/facebook/react/pull/7005))1934- Ensure controlled `<select>` components behave the same on initial render as they do on updates. ([@yiminghe](https://github.com/yiminghe) in [#5362](https://github.com/facebook/react/pull/5362))19351936### React Perf Add-on1937- Add `isRunning()` API. ([@nfcampos](https://github.com/nfcampos) in [#6763](https://github.com/facebook/react/pull/6763))1938- Improve accuracy of lifecycle hook timing. ([@gaearon](https://github.com/gaearon) in [#6858](https://github.com/facebook/react/pull/6858))1939- Fix internal errors when using ReactPerf with portal components. ([@gaearon](https://github.com/gaearon) in [#6860](https://github.com/facebook/react/pull/6860))1940- Fix performance regression. ([@sophiebits](https://github.com/sophiebits) in [#6770](https://github.com/facebook/react/pull/6770))1941- Add warning that ReactPerf is not enabled in production. ([@sashashakun](https://github.com/sashashakun) in [#6884](https://github.com/facebook/react/pull/6884))19421943### React CSSTransitionGroup Add-on1944- Fix timing issue with `null` node. ([@keyanzhang](https://github.com/keyanzhang) in [#6958](https://github.com/facebook/react/pull/6958))19451946### React Native Renderer1947- Dependencies on React Native modules use CommonJS requires instead of providesModule. ([@davidaurelio](https://github.com/davidaurelio) in [#6715](https://github.com/facebook/react/pull/6715))194819491950## 15.1.0 (May 20, 2016)19511952### React1953- Ensure we're using the latest `object-assign`, which has protection against a non-spec-compliant native `Object.assign`. ([@zpao](https://github.com/zpao) in [#6681](https://github.com/facebook/react/pull/6681))1954- Add a new warning to communicate that `props` objects passed to `createElement` must be plain objects. ([@richardscarrott](https://github.com/richardscarrott) in [#6134](https://github.com/facebook/react/pull/6134))1955- Fix a batching bug resulting in some lifecycle methods incorrectly being called multiple times. ([@sophiebits](https://github.com/sophiebits) in [#6650](https://github.com/facebook/react/pull/6650))19561957### React DOM1958- Fix regression in custom elements support. ([@jscissr](https://github.com/jscissr) in [#6570](https://github.com/facebook/react/pull/6570))1959- Stop incorrectly warning about using `onScroll` event handler with server rendering. ([@Aweary](https://github.com/Aweary) in [#6678](https://github.com/facebook/react/pull/6678))1960- Fix grammar in the controlled input warning. ([@jakeboone02](https://github.com/jakeboone02) in [#6657](https://github.com/facebook/react/pull/6657))1961- Fix issue preventing `<object>` nodes from being able to read `<param>` nodes in IE. ([@syranide](https://github.com/syranide) in [#6691](https://github.com/facebook/react/pull/6691))1962- Fix issue resulting in crash when using experimental error boundaries with server rendering. ([@jimfb](https://github.com/jimfb) in [#6694](https://github.com/facebook/react/pull/6694))1963- Add additional information to the controlled input warning. ([@borisyankov](https://github.com/borisyankov) in [#6341](https://github.com/facebook/react/pull/6341))19641965### React Perf Add-on1966- Completely rewritten to collect data more accurately and to be easier to maintain. ([@gaearon](https://github.com/gaearon) in [#6647](https://github.com/facebook/react/pull/6647), [#6046](https://github.com/facebook/react/pull/6046))19671968### React Native Renderer1969- Remove some special cases for platform specific branching. ([@sebmarkbage](https://github.com/sebmarkbage) in [#6660](https://github.com/facebook/react/pull/6660))1970- Remove use of `merge` utility. ([@sebmarkbage](https://github.com/sebmarkbage) in [#6634](https://github.com/facebook/react/pull/6634))1971- Renamed some modules to better indicate usage ([@javache](https://github.com/javache) in [#6643](https://github.com/facebook/react/pull/6643))197219731974## 15.0.2 (April 29, 2016)19751976### React1977- Removed extraneous files from npm package. ([@gaearon](https://github.com/gaearon) in [#6388](https://github.com/facebook/react/pull/6388))1978- Ensure `componentWillUnmount` is only called once. ([@jimfb](https://github.com/jimfb) in [#6613](https://github.com/facebook/react/pull/6613))19791980### ReactDOM1981- Fixed bug resulting in disabled buttons responding to mouse events in IE. ([@nhunzaker](https://github.com/nhunzaker) in [#6215](https://github.com/facebook/react/pull/6215))1982- Ensure `<option>`s are correctly selected when inside `<optgroup>`. ([@trevorsmith](https://github.com/trevorsmith) in [#6442](https://github.com/facebook/react/pull/6442))1983- Restore support for rendering into a shadow root. ([@Wildhoney](https://github.com/Wildhoney) in [#6462](https://github.com/facebook/react/pull/6462))1984- Ensure nested `<body>` elements are caught when warning for invalid markup. ([@keyanzhang](https://github.com/keyanzhang) in [#6469](https://github.com/facebook/react/pull/6469))1985- Improve warning when encountering multiple elements with the same key. ([@hkal](https://github.com/hkal) in [#6500](https://github.com/facebook/react/pull/6500))19861987### React TestUtils Add-on1988- Ensure that functional components do not have an owner. ([@gaearon](https://github.com/gaearon) in [#6362](https://github.com/facebook/react/pull/6362))1989- Handle invalid arguments to `scryRenderedDOMComponentsWithClass` better. ([@ipeters90](https://github.com/ipeters90) in [#6529](https://github.com/facebook/react/pull/6529))19901991### React Perf Add-on1992- Ignore DOM operations that occur outside the batch operation. ([@gaearon](https://github.com/gaearon) in [#6516](https://github.com/facebook/react/pull/6516))19931994### React Native Renderer1995- These files are now shipped inside the React npm package. They have no impact on React core or ReactDOM.199619971998## 15.0.1 (April 8, 2016)19992000### React