• Provide a component stack as a second argument to onRecoverableError. (@gnoff in #24591)
• Fix hydrating into document causing a blank page on mismatch. (@gnoff in #24523)
• Fix false positive hydration errors with Suspense. (@gnoff in #24480 and @acdlite in #24532)
• Fix ignored setState in Safari when adding an iframe. (@gaearon in #24459)

• Pass information about server errors to the client. (@salazarm and @gnoff in #24551 and #24591)
• Allow to provide a reason when aborting the HTML stream. (@gnoff in #24680)
• Eliminate extraneous text separators in the HTML where possible. (@gnoff in #24630)
• Disallow complex children inside <title> elements to match the browser constraints. (@gnoff in #24679)
• Fix buffering in some worker environments by explicitly setting highWaterMark to 0. (@jplhomer in #24641)

• Add support for useId() inside Server Components. (@gnoff in #24172)

• Fix the false positive warning about react-dom/client when using UMD bundle. (@alireza-molaee in #24274)
• Fix suppressHydrationWarning to work in production too. (@gaearon in #24271)
• Fix componentWillUnmount firing twice inside of Suspense. (@acdlite in #24308)
• Fix some transition updates being ignored. (@acdlite in #24353)
• Fix useDeferredValue causing an infinite loop when passed an unmemoized value. (@acdlite in #24247)
• Fix throttling of revealing Suspense fallbacks. (@sunderls in #24253)
• Fix an inconsistency in whether the props object is the same between renders. (@Andarist and @acdlite in #24421)
• Fix a missing warning about a setState loop in useEffect. (@gaearon in #24298)
• Fix a spurious hydration error. (@gnoff in #24404)
• Warn when calling setState in useInsertionEffect. (@gaearon in #24295)
• Ensure the reason for hydration errors is always displayed. (@gaearon in #24276)

• Fix escaping for the bootstrapScriptContent contents. (@gnoff in #24385)
• Significantly improve performance of renderToPipeableStream. (@gnoff in #24291)

• Fix false positive errors with a large number of branches. (@scyron6 in #24287)
• Don't consider a known dependency stable when the variable is reassigned. (@afzalsayed96 in #24343)

• Replace the implementation with the use-sync-external-store shim. (@gaearon in #24289)

Below is a list of all new features, APIs, deprecations, and breaking changes. Read React 18 release post and React 18 upgrade guide for more information.

• 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.
• 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).
• 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.
• 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.
• 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.

These new APIs are now exported from react-dom/client:

• 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.
• 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.

Both 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, or console.error in the older browsers.

These new APIs are now exported from react-dom/server and have full support for streaming Suspense on the server:

• renderToPipeableStream: for streaming in Node environments.
• renderToReadableStream: for modern edge runtime environments, such as Deno and Cloudflare workers.

The existing renderToString method keeps working but is discouraged.

• react-dom: ReactDOM.render has been deprecated. Using it will warn and run your app in React 17 mode.
• react-dom: ReactDOM.hydrate has been deprecated. Using it will warn and run your app in React 17 mode.
• react-dom: ReactDOM.unmountComponentAtNode has been deprecated.
• react-dom: ReactDOM.renderSubtreeIntoContainer has been deprecated.
• react-dom/server: ReactDOMServer.renderToNodeStream has been deprecated.

• 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 for more info. In the rare case that you need to opt out, wrap the state update in flushSync.
• 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.
• 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.
• 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.
• 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.
• 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.
• 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.

• Remove unstable scheduler/tracing API

• 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.
• 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 mechanism so you can enable them only for unit tests where they are useful and beneficial.
• 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 this warning.
• 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 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.
• 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.

• 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.
• 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.

• Add useTransition and useDeferredValue to separate urgent updates from transitions. (#10426, #10715, #15593, #15272, #15578, #15769, #17058, #18796, #19121, #19703, #19719, #19724, #20672, #20976 by @acdlite, @lunaruan, @rickhanlonii, and @sebmarkbage)
• Add useId for generating unique IDs. (#17322, #18576, #22644, #22672, #21260 by @acdlite, @lunaruan, and @sebmarkbage)
• Add useSyncExternalStore to help external store libraries integrate with React. (#15022, #18000, #18771, #22211, #22292, #22239, #22347, #23150 by @acdlite, @bvaughn, and @drarmstr)
• Add startTransition as a version of useTransition without pending feedback. (#19696 by @rickhanlonii)
• Add useInsertionEffect for CSS-in-JS libraries. (#21913 by @rickhanlonii)
• Make Suspense remount layout effects when content reappears. (#19322, #19374, #19523, #20625, #21079 by @acdlite, @bvaughn, and @lunaruan)
• Make <StrictMode> re-run effects to check for restorable state. (#19523 , #21418 by @bvaughn and @lunaruan)
• Assume Symbols are always available. (#23348 by @sebmarkbage)
• Remove object-assign polyfill. (#23351 by @sebmarkbage)
• Remove unsupported unstable_changedBits API. (#20953 by @acdlite)
• Allow components to render undefined. (#21869 by @rickhanlonii)
• Flush useEffect resulting from discrete events like clicks synchronously. (#21150 by @acdlite)
• Suspense fallback={undefined} now behaves the same as null and isn't ignored. (#21854 by @rickhanlonii)
• Consider all lazy() resolving to the same component equivalent. (#20357 by @sebmarkbage)
• Don't patch console during first render. (#22308 by @lunaruan)
• Improve memory usage. (#21039 by @bgirard)
• Improve messages if string coercion throws (Temporal.*, Symbol, etc.) (#22064 by @justingrant)
• Use setImmediate when available over MessageChannel. (#20834 by @gaearon)
• Fix context failing to propagate inside suspended trees. (#23095 by @gaearon)
• Fix useReducer observing incorrect props by removing the eager bailout mechanism. (#22445 by @josephsavona)
• Fix setState being ignored in Safari when appending iframes. (#23111 by @gaearon)
• Fix a crash when rendering ZonedDateTime in the tree. (#20617 by @dimaqq)
• Fix a crash when document is set to null in tests. (#22695 by @SimenB)
• Fix onLoad not triggering when concurrent features are on. (#23316 by @gnoff)
• Fix a warning when a selector returns NaN. (#23333 by @hachibeeDI)
• Fix the generated license header. (#23004 by @vitaliemiron)
• Add package.json as one of the entry points. (#22954 by @Jack)
• Allow suspending outside a Suspense boundary. (#23267 by @acdlite)
• Log a recoverable error whenever hydration fails. (#23319 by @acdlite)

• Add createRoot and hydrateRoot. (#10239, #11225, #12117, #13732, #15502, #15532, #17035, #17165, #20669, #20748, #20888, #21072, #21417, #21652, #21687, #23207, #23385 by @acdlite, @bvaughn, @gaearon, @lunaruan, @rickhanlonii, @trueadm, and @sebmarkbage)
• Add selective hydration. (#14717, #14884, #16725, #16880, #17004, #22416, #22629, #22448, #22856, #23176 by @acdlite, @gaearon, @salazarm, and @sebmarkbage)
• Add aria-description to the list of known ARIA attributes. (#22142 by @mahyareb)
• Add onResize event to video elements. (#21973 by @rileyjshaw)
• Add imageSizes and imageSrcSet to known props. (#22550 by @eps1lon)
• Allow non-string <option> children if value is provided. (#21431 by @sebmarkbage)
• Fix aspectRatio style not being applied. (#21100 by @gaearon)
• Warn if renderSubtreeIntoContainer is called. (#23355 by @acdlite)

• Add the new streaming renderer. (#14144, #20970, #21056, #21255, #21200, #21257, #21276, #22443, #22450, #23247, #24025, #24030 by @sebmarkbage)
• Fix context providers in SSR when handling multiple requests. (#23171 by @frandiox)
• Revert to client render on text mismatch. (#23354 by @acdlite)
• Deprecate renderToNodeStream. (#23359 by @sebmarkbage)
• Fix a spurious error log in the new server renderer. (#24043 by @eps1lon)
• Fix a bug in the new server renderer. (#22617 by @shuding)
• Ignore function and symbol values inside custom elements on the server. (#21157 by @sebmarkbage)

• Throw when act is used in production. (#21686 by @acdlite)
• Support disabling spurious act warnings with global.IS_REACT_ACT_ENVIRONMENT. (#22561 by @acdlite)
• Expand act warning to cover all APIs that might schedule React work. (#22607 by @acdlite)
• Make act batch updates. (#21797 by @acdlite)
• Remove warning for dangling passive effects. (#22609 by @acdlite)

• Track late-mounted roots in Fast Refresh. (#22740 by @anc95)
• Add exports field to package.json. (#23087 by @otakustay)

• Add Server Context support. (#23244 by @salazarm)
• Add lazy support. (#24068 by @gnoff)
• Update webpack plugin for webpack 5 (#22739 by @michenly)
• Fix a mistake in the Node loader. (#22537 by @btea)
• Use globalThis instead of window for edge environments. (#22777 by @huozhi)

• Remove unstable scheduler/tracing API (#20037 by @bvaughn)

• Remove an unused dependency to address the SharedArrayBuffer cross-origin isolation warning. (@koba04 and @bvaughn in #20831, #20832, and #20840)

• Fix a crash in IE11. (@gaearon in #20071)

Today, we are releasing React 17!

Learn more about React 17 and how to update to it on the official React blog.

• Add react/jsx-runtime and react/jsx-dev-runtime for the new JSX transform. (@lunaruan in #18299)
• Build component stacks from native error frames. (@sebmarkbage in #18561)
• Allow to specify displayName on context for improved stacks. (@eps1lon in #18224)
• Prevent 'use strict' from leaking in the UMD bundles. (@koba04 in #19614)
• Stop using fb.me for redirects. (@cylim in #19598)

• Delegate events to roots instead of document. (@trueadm in #18195 and others)
• Clean up all effects before running any next effects. (@bvaughn in #17947)
• Run useEffect cleanup functions asynchronously. (@bvaughn in #17925)
• Use browser focusin and focusout for onFocus and onBlur. (@trueadm in #19186)
• Make all Capture events use the browser capture phase. (@trueadm in #19221)
• Don't emulate bubbling of the onScroll event. (@gaearon in #19464)
• Throw if forwardRef or memo component returns undefined. (@gaearon in #19550)
• Remove event pooling. (@trueadm in #18969)
• Stop exposing internals that won’t be needed by React Native Web. (@necolas in #18483)
• Attach all known event listeners when the root mounts. (@gaearon in #19659)
• Disable console in the second render pass of DEV mode double render. (@sebmarkbage in #18547)
• Deprecate the undocumented and misleading ReactTestUtils.SimulateNative API. (@gaearon in #13407)
• Rename private field names used in the internals. (@gaearon in #18377)
• Don't call User Timing API in development. (@gaearon in #18417)
• Disable console during the repeated render in Strict Mode. (@sebmarkbage in #18547)
• In Strict Mode, double-render components without Hooks too. (@eps1lon in #18430)
• Allow calling ReactDOM.flushSync during lifecycle methods (but warn). (@sebmarkbage in #18759)
• Add the code property to the keyboard event objects. (@bl00mber in #18287)
• Add the disableRemotePlayback property for video elements. (@tombrowndev in #18619)
• Add the enterKeyHint property for input elements. (@eps1lon in #18634)
• Warn when no value is provided to <Context.Provider>. (@charlie1404 in #19054)
• Warn when memo or forwardRef components return undefined. (@bvaughn in #19550)
• Improve the error message for invalid updates. (@JoviDeCroock in #18316)
• Exclude forwardRef and memo from stack frames. (@sebmarkbage in #18559)
• Improve the error message when switching between controlled and uncontrolled inputs. (@vcarl in #17070)
• Keep onTouchStart, onTouchMove, and onWheel passive. (@gaearon in #19654)
• Fix setState hanging in development inside a closed iframe. (@gaearon in #19220)
• Fix rendering bailout for lazy components with defaultProps. (@jddxf in #18539)
• Fix a false positive warning when dangerouslySetInnerHTML is undefined. (@eps1lon in #18676)
• Fix Test Utils with non-standard require implementation. (@just-boris in #18632)
• Fix onBeforeInput reporting an incorrect event.type. (@eps1lon in #19561)
• Fix event.relatedTarget reported as undefined in Firefox. (@claytercek in #19607)
• Fix "unspecified error" in IE11. (@hemakshis in #19664)
• Fix rendering into a shadow root. (@Jack-Works in #15894)
• Fix movementX/Y polyfill with capture events. (@gaearon in #19672)
• Use delegation for onSubmit and onReset events. (@gaearon in #19333)
• Improve memory usage. (@trueadm in #18970)

• Make useCallback behavior consistent with useMemo for the server renderer. (@alexmckenley in #18783)
• Fix state leaking when a function component throws. (@pmaccart in #19212)

• Improve findByType error message. (@henryqdineen in #17439)

• Revamp the priority batching heuristics. (@acdlite in #18796)
• Add the unstable_ prefix before the experimental APIs. (@acdlite in #18825)
• Remove unstable_discreteUpdates and unstable_flushDiscreteUpdates. (@trueadm in #18825)
• Remove the timeoutMs argument. (@acdlite in #19703)
• Disable <div hidden /> prerendering in favor of a different future API. (@acdlite in #18917)
• Add unstable_expectedLoadTime to Suspense for CPU-bound trees. (@acdlite in #19936)
• Add an experimental unstable_useOpaqueIdentifier Hook. (@lunaruan in #17322)
• Add an experimental unstable_startTransition API. (@rickhanlonii in #19696)
• Using act in the test renderer no longer flushes Suspense fallbacks. (@acdlite in #18596)
• Use global render timeout for CPU Suspense. (@sebmarkbage in #19643)
• Clear the existing root content before mounting. (@bvaughn in #18730)
• Fix a bug with error boundaries. (@acdlite in #18265)
• Fix a bug causing dropped updates in a suspended tree. (@acdlite in #18384 and #18457)
• Fix a bug causing dropped render phase updates. (@acdlite in #18537)
• Fix a bug in SuspenseList. (@sebmarkbage in #18412)
• Fix a bug causing Suspense fallback to show too early. (@acdlite in #18411)
• Fix a bug with class components inside SuspenseList. (@sebmarkbage in #18448)
• Fix a bug with inputs that may cause updates to be dropped. (@jddxf in #18515 and @acdlite in #18535)
• Fix a bug causing Suspense fallback to get stuck. (@acdlite in #18663)
• Don't cut off the tail of a SuspenseList if hydrating. (@sebmarkbage in #18854)
• Fix a bug in useMutableSource that may happen when getSnapshot changes. (@bvaughn in #18297)
• Fix a tearing bug in useMutableSource. (@bvaughn in #18912)
• Warn if calling setState outside of render but before commit. (@sebmarkbage in #18838)

• Add support for the new JSX transform. (@lunaruan in #18299)

• 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 in #18238)
• Revert warning for cross-component updates that happen inside class render lifecycles (componentWillReceiveProps, shouldComponentUpdate, and so on). (@gaearon in #18330)

• Warn when a string ref is used in a manner that's not amenable to a future codemod (@lunaruan in #17864)
• Deprecate React.createFactory() (@trueadm in #17878)

• Warn when changes in style may cause an unexpected collision (@sophiebits in #14181, #18002)
• Warn when a function component is updated during another component's render phase (@acdlite in #17099)
• Deprecate unstable_createPortal (@trueadm in #17880)
• Fix onMouseEnter being fired on disabled buttons (@AlfredoGJ in #17675)
• Call shouldComponentUpdate twice when developing in StrictMode (@bvaughn in #17942)
• Add version property to ReactDOM (@ealush in #15780)
• Don't call toString() of dangerouslySetInnerHTML (@sebmarkbage in #17773)
• Show component stacks in more warnings (@gaearon in #17922, #17586)

• Warn for problematic usages of ReactDOM.createRoot() (@trueadm in #17937)
• Remove ReactDOM.createRoot() callback params and added warnings on usage (@bvaughn in #17916)
• Don't group Idle/Offscreen work with other work (@sebmarkbage in #17456)
• Adjust SuspenseList CPU bound heuristic (@sebmarkbage in #17455)
• Add missing event plugin priorities (@trueadm in #17914)
• Fix isPending only being true when transitioning from inside an input event (@acdlite in #17382)
• Fix React.memo components dropping updates when interrupted by a higher priority update (@acdlite in #18091)
• Don't warn when suspending at the wrong priority (@gaearon in #17971)
• Fix a bug with rebasing updates (@acdlite and @sebmarkbage in #17560, #17510, #17483, #17480)

• Fix passive effects (useEffect) not being fired in a multi-root app. (@acdlite in #17347)

• Fix lazy and memo types considered elements instead of components (@bvaughn in #17278)

• Fix mouseenter handlers from firing twice inside nested React containers. @yuanoook in #16928
• Remove unstable_createRoot and unstable_createSyncRoot experimental APIs. (These are available in the Experimental channel as createRoot and createSyncRoot.) (@acdlite in #17088)

• Fix regression in react-native-web by restoring order of arguments in event plugin extractors (@necolas in #16978)

• Fix regression in Next.js apps by allowing Suspense mismatch during hydration to silently proceed (@sebmarkbage in #16943)

• Fix edge case where a hook update wasn't being memoized. (@sebmarkbage in #16359)
• Fix heuristic for determining when to hydrate, so we don't incorrectly hydrate during an update. (@sebmarkbage in #16739)
• Clear additional fiber fields during unmount to save memory. (@trueadm in #16807)
• Fix bug with required text fields in Firefox. (@halvves in #16578)
• Prefer Object.is instead of inline polyfill, when available. (@ku8ar in #16212)
• Fix bug when mixing Suspense and error handling. (@acdlite in #16801)

• Improve queue performance by switching its internal data structure to a min binary heap. (@acdlite in #16245)
• Use postMessage loop with short intervals instead of attempting to align to frame boundaries with requestAnimationFrame. (@acdlite in #16214)

• Avoid tearing issue when a mutation happens and the previous update is still in progress. (@bvaughn in #16623)

• Add <React.Profiler> API for gathering performance measurements programmatically. (@bvaughn in #15172)
• Remove unstable_ConcurrentMode in favor of unstable_createRoot. (@acdlite in #15532)

• Deprecate old names for the UNSAFE_* lifecycle methods. (@bvaughn in #15186 and @threepointone in #16103)
• Deprecate javascript: URLs as a common attack surface. (@sebmarkbage in #15047)
• Deprecate uncommon "module pattern" (factory) components. (@sebmarkbage in #15145)
• Add support for the disablePictureInPicture attribute on <video>. (@eek in #15334)
• Add support for onLoad event for <embed>. (@cherniavskii in #15614)
• Add support for editing useState state from DevTools. (@bvaughn in #14906)
• Add support for toggling Suspense from DevTools. (@gaearon in #15232)
• Warn when setState is called from useEffect, creating a loop. (@gaearon in #15180)
• Fix a memory leak. (@paulshen in #16115)
• Fix a crash inside findDOMNode for components wrapped in <Suspense>. (@acdlite in #15312)
• Fix pending effects from being flushed too late. (@acdlite in #15650)
• Fix incorrect argument order in a warning message. (@brickspert in #15345)
• Fix hiding Suspense fallback nodes when there is an !important style. (@acdlite in #15861 and #15882)
• Slightly improve hydration performance. (@bmeurer in #15998)

• Fix incorrect output for camelCase custom CSS property names. (@bedakb in #16167)

• Add act(async () => ...) for testing asynchronous state updates. (@threepointone in #14853)
• Add support for nesting act from different renderers. (@threepointone in #16039 and #16042)
• Warn in Strict Mode if effects are scheduled outside an act() call. (@threepointone in #15763 and #16041)
• Warn when using act from the wrong renderer. (@threepointone in #15756)

• Report Hook calls at the top level as a violation. (gaearon in #16455)

• Fix an incorrect bailout in useReducer(). (@acdlite in #15124)
• Fix iframe warnings in Safari DevTools. (@renanvalentin in #15099)
• Warn if contextType is set to Context.Consumer instead of Context. (@aweary in #14831)
• Warn if contextType is set to invalid values. (@gaearon in #15142)

• Don't set the first option as selected in select tag with size attribute. (@kulek1 in #14242)
• Improve the useEffect(async () => ...) warning message. (@gaearon in #15118)
• Improve the error message sometimes caused by duplicate React. (@jaredpalmer in #15139)

• Improve the useLayoutEffect warning message when server rendering. (@gaearon in #15158)

• Fix setState in shallow renderer to work with Hooks. (@gaearon in #15120)
• Fix shallow renderer to support React.memo. (@aweary in #14816)
• Fix shallow renderer to support Hooks inside forwardRef. (@eps1lon in #15100)

• Fix a bug where DevTools caused a runtime error when inspecting a component that used a useContext hook. (@bvaughn in #14940)

• Fix a bug that caused inputs to behave incorrectly in UMD builds. (@gaearon in #14914)
• Fix a bug that caused render phase updates to be discarded. (@gaearon in #14852)

• Unwind the context stack when a stream is destroyed without completing, to prevent incorrect values during a subsequent render. (@overlookmotel in #14706)

• Add a new recommended exhaustive-deps rule. (@gaearon in #14636)

• Fix ReactDOM.render being ignored inside useEffect. (@gaearon in #14799)
• Fix a crash when unmounting empty portals. (@gaearon in #14820)
• Fix useImperativeHandle to work correctly when no deps are specified. (@gaearon in #14801)
• Fix crossOrigin attribute to work in SVG image elements. (@aweary in #14832)
• Fix a false positive warning when using Suspense with Hooks. (@gaearon in #14821)

• Include component stack into the act() warning. (@threepointone in #14855)

• Fix a crash when used together with an older version of React. (@bvaughn in #14770)

• Fix a crash in Node environment. (@threepointone in #14768)

• Add Hooks — a way to use state and other React features without writing a class. (@acdlite et al. in #13968)
• Improve the useReducer Hook lazy initialization API. (@acdlite in #14723)

• Bail out of rendering on identical values for useState and useReducer Hooks. (@acdlite in #14569)
• Use Object.is algorithm for comparing useState and useReducer values. (@Jessidhia in #14752)
• Don’t compare the first argument passed to useEffect/useMemo/useCallback Hooks. (@acdlite in #14594)
• Support synchronous thenables passed to React.lazy(). (@gaearon in #14626)
• Render components with Hooks twice in Strict Mode (DEV-only) to match class behavior. (@gaearon in #14654)
• Warn about mismatching Hook order in development. (@threepointone in #14585 and @acdlite in #14591)
• Effect clean-up functions must return either undefined or a function. All other values, including null, are not allowed. @acdlite in #14119

• Support Hooks in the shallow renderer. (@trueadm in #14567)
• Fix wrong state in shouldComponentUpdate in the presence of getDerivedStateFromProps for Shallow Renderer. (@chenesan in #14613)
• Add ReactTestRenderer.act() and ReactTestUtils.act() for batching updates so that tests more closely match real behavior. (@threepointone in #14744)

• Initial release. (@calebmer in #13968)
• Fix reporting after encountering a loop. (@calebmer and @Yurickh in #14661)
• Don't consider throwing to be a rule violation. (@sophiebits in #14040)

• Fix performance of React.lazy for large numbers of lazily-loaded components. (@acdlite in #14429)
• Clear fields on unmount to avoid memory leaks. (@trueadm in #14276)
• Fix bug with SSR and context when mixing react-dom/server@16.6 and react@<16.6. (@gaearon in #14291)
• Fix a performance regression in profiling mode. (@bvaughn in #14383)

• Post to MessageChannel instead of window. (@acdlite in #14234)
• Reduce serialization overhead. (@developit in #14249)
• Fix fallback to setTimeout in testing environments. (@bvaughn in #14358)
• Add methods for debugging. (@mrkev in #14053)

• Fix bugs in Suspense and lazy. (@acdlite in #14133, #14157, and #14164)
• Fix highlighting of React.memo updates in React DevTools. (@bvaughn in #14141)
• Fix interaction of Suspense with the React Profiler. (@bvaughn in #14065)
• Fix a false positive warning when using Suspense. (@acdlite in #14158)

• Fix incorrect sharing of context state between renderToNodeStream() calls. (@sebmarkbage in #14182)
• Add a warning about incorrect usage of the context API. (@trueadm in #14033)

This release was published in a broken state and should be skipped.

• Fallback should not remount every time a promise resolves. (@acdlite in #14083)
• Fix bug where Suspense keeps showing fallback even after everything finishes loading. (@acdlite in #14083)
• Fix a crash when Suspense finishes loading in IE11. (@sophiebits in #14126)
• Fix unresolved default props in lifecycle methods of a lazy component. (@gaearon in #14112)
• Fix bug when recovering from an error thrown during complete phase. (@gaearon in #14104)

• Switch from deadline object to shouldYield API. (@acdlite in #14025)

• Add React.memo() as an alternative to PureComponent for functions. (@acdlite in #13748)
• Add React.lazy() for code splitting components. (@acdlite in #13885)
• React.StrictMode now warns about legacy context API. (@bvaughn in #13760)
• React.StrictMode now warns about findDOMNode. (@sebmarkbage in #13841)
• Rename unstable_AsyncMode to unstable_ConcurrentMode. (@trueadm in #13732)
• Rename unstable_Placeholder to Suspense, and delayMs to maxDuration. (@gaearon in #13799 and @sebmarkbage in #13922)

• Add contextType as a more ergonomic way to subscribe to context from a class. (@bvaughn in #13728)
• Add getDerivedStateFromError lifecycle method for catching errors in a future asynchronous server-side renderer. (@bvaughn in #13746)
• Warn when <Context> is used instead of <Context.Consumer>. (@trueadm in #13829)
• Fix gray overlay on iOS Safari. (@philipp-spiess in #13778)
• Fix a bug caused by overwriting window.event in development. (@sergei-startsev in #13697)

• Add support for React.memo(). (@alexmckenley in #13855)
• Add support for contextType. (@alexmckenley and @sebmarkbage in #13889)

• Rename the package to scheduler. (@gaearon in #13683)
• Support priority levels, continuations, and wrapped callbacks. (@acdlite in #13720 and #13842)
• Improve the fallback mechanism in non-DOM environments. (@acdlite in #13740)
• Schedule requestAnimationFrame earlier. (@acdlite in #13785)
• Fix the DOM detection to be more thorough. (@trueadm in #13731)
• Fix bugs with interaction tracing. (@bvaughn in #13590)
• Add the envify transform to the package. (@mridgway in #13766)

• Fixed a recent <iframe> regression (@JSteunou in #13650)
• Fix updateWrapper so that <textarea>s no longer re-render when data is unchanged (@joelbarbosa in #13643)

• Renaming "tracking" API to "tracing" (@bvaughn in #13641)
• Add UMD production+profiling entry points (@bvaughn in #13642)
• Refactored schedule to remove some React-isms and improve performance for when deferred updates time out (@acdlite in #13582)

• Improve the warning when React.forwardRef receives an unexpected number of arguments. (@andresroberto in #13636)

• Fix a regression in unstable exports used by React Native Web. (@aweary in #13598)
• Fix a crash when component defines a method called isReactComponent. (@gaearon in #13608)
• Fix a crash in development mode in IE9 when printing a warning. (@link-alex in #13620)
• Provide a better error message when running react-dom/profiling with schedule/tracking. (@bvaughn in #13605)
• If a ForwardRef component defines a displayName, use it in warnings. (@probablyup in #13615)

• Add a separate profiling entry point at schedule/tracking-profiling. (@bvaughn in #13605)

• Add a warning if React.forwardRef render function doesn't take exactly two arguments (@bvaughn in #13168)
• Improve the error message when passing an element to createElement by mistake (@DCtheTall in #13131)
• Don't call profiler onRender until after mutations (@bvaughn in #13572)

• Add support for React DevTools Profiler (@bvaughn in #13058)
• Add react-dom/profiling entry point alias for profiling in production (@bvaughn in #13570)
• Add onAuxClick event for browsers that support it (@jquense in #11571)
• Add movementX and movementY fields to mouse events (@jasonwilliams in #9018)
• Add tangentialPressure and twist fields to pointer events (@motiz88 in #13374)
• Minimally support iframes (nested browsing contexts) in selection event handling (@acusti in #12037)
• Support passing booleans to the focusable SVG attribute (@gaearon in #13339)
• Ignore <noscript> on the client when hydrating (@Ephem in #13537)
• Fix gridArea to be treated as a unitless CSS property (@mgol in #13550)
• Fix incorrect data in compositionend event when typing Korean on IE11 (@crux153 in #12563)
• Fix a crash when using dynamic children in the <option> tag (@Slowyn in #13261, @gaearon in #13465)
• Fix the checked attribute not getting initially set on the input (@dilidili in #13114)
• Fix hydration of dangerouslySetInnerHTML when __html is not a string (@gaearon in #13353)
• Fix a warning about missing controlled onChange to fire on falsy values too (@nicolevy in #12628)
• Fix submit and reset buttons getting an empty label (@ellsclytn in #12780)
• Fix the onSelect event not being triggered after drag and drop (@gaearon in #13422)
• Fix the onClick event not working inside a portal on iOS (@aweary in #11927)
• Fix a performance issue when thousands of roots are re-rendered (@gaearon in #13335)
• Fix a performance regression that also caused onChange to not fire in some cases (@gaearon in #13423)
• Handle errors in more edge cases gracefully (@gaearon in #13237 and @acdlite in #13269)
• Don't use proxies for synthetic events in development (@gaearon in #12171)
• Warn when "false" or "true" is the value of a boolean DOM prop (@motiz88 in #13372)
• Warn when this.state is initialized to props (@veekas in #11658)
• Don't compare style on hydration in IE due to noisy false positives (@mgol in #13534)
• Include StrictMode in the component stack (@gaearon in #13240)
• Don't overwrite window.event in IE (@ConradIrwin in #11696)
• Improve component stack for the folder/index.js naming convention (@gaearon in #12059)
• Improve a warning when using getDerivedStateFromProps without initialized state (@flxwu in #13317)
• Improve a warning about invalid textarea usage (@raunofreiberg in #13361)
• Treat invalid Symbol and function values more consistently (@raunofreiberg in #13362 and #13389)
• Allow Electron <webview> tag without warnings (@philipp-spiess in #13301)
• Don't show the uncaught error addendum if e.preventDefault() was called (@gaearon in #13384)
• Warn about rendering Generators (@gaearon in #13312)
• Remove irrelevant suggestion of a legacy method from a warning (@zx6658 in #13169)
• Remove unstable_deferredUpdates in favor of unstable_scheduleWork from schedule (@gaearon in #13488)
• Fix unstable asynchronous mode from doing unnecessary work when an update takes too long (@acdlite in #13503)

• Fix crash with nullish children when using dangerouslySetInnerHtml in a selected <option> (@mridgway in #13078)
• Fix crash when setTimeout is missing (@dustinsoftware in #13088)

• Fix this in a functional component for shallow renderer to be undefined (@koba04 in #13144)
• Deprecate a Jest-specific ReactTestUtils.mockComponent() helper (@bvaughn in #13193)
• Warn about ReactDOM.createPortal usage within the test renderer (@bvaughn in #12895)
• Improve a confusing error message (@gaearon in #13351)

• Add support for DevTools (@yunchancho in #13173)

• 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 in #12624)

• Fix a potential XSS vulnerability when the attacker controls an attribute name (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 in #13302)

• 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 in #13303)

• You can now assign propTypes to components returned by React.ForwardRef. (@bvaughn in #12911)

• Fix a crash when the input type changes from some other types to text. (@spirosikmd in #12135)
• Fix a crash in IE11 when restoring focus to an SVG element. (@ThaddeusJiang in #12996)
• Fix a range input not updating in some cases. (@Illu in #12939)
• Fix input validation triggering unnecessarily in Firefox. (@nhunzaker in #12925)
• Fix an incorrect event.target value for the onChange event in IE9. (@nhunzaker in #12976)
• Fix a false positive error when returning an empty <React.Fragment /> from a component. (@philipp-spiess in #12966)

• Fix an incorrect value being provided by new context API. (@ericsoderberghp in #12985, @gaearon in #13019)

• Allow multiple root children in test renderer traversal API. (@gaearon in #13017)
• Fix getDerivedStateFromProps() in the shallow renderer to not discard the pending state. (@fatfisz in #13030)

• Add a new experimental React.unstable_Profiler component for measuring performance. (@bvaughn in #12745)

• Add support for the Pointer Events specification. (@philipp-spiess in #12507)
• Properly call getDerivedStateFromProps() regardless of the reason for re-rendering. (@acdlite in #12600 and #12802)
• Fix a bug that prevented context propagation in some cases. (@gaearon in #12708)
• Fix re-rendering of components using forwardRef() on a deeper setState(). (@gaearon in #12690)
• Fix some attributes incorrectly getting removed from custom element nodes. (@airamrguez in #12702)
• Fix context providers to not bail out on children if there's a legacy context provider above. (@gaearon in #12586)
• Add the ability to specify propTypes on a context provider component. (@nicolevy in #12658)
• Fix a false positive warning when using react-lifecycles-compat in <StrictMode>. (@bvaughn in #12644)
• Warn when the forwardRef() render function has propTypes or defaultProps. (@bvaughn in #12644)
• Improve how forwardRef() and context consumers are displayed in the component stack. (@sophiebits in #12777)
• Change internal event names. This can break third-party packages that rely on React internals in unsupported ways. (@philipp-spiess in #12629)

• Fix the getDerivedStateFromProps() support to match the new React DOM behavior. (@koba04 in #12676)
• Fix a testInstance.parent crash when the parent is a fragment or another special node. (@gaearon in #12813)
• forwardRef() components are now discoverable by the test renderer traversal methods. (@gaearon in #12725)
• Shallow renderer now ignores setState() updaters that return null or undefined. (@koba04 in #12756)

• Fix reading context provided from the tree managed by React DOM. (@acdlite in #12779)

• 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 in #12820)

• The new host config shape is flat and doesn't use nested objects. (@gaearon in #12792)

• Fix a potential XSS vulnerability when the attacker controls an attribute name (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 in #13302)

• Improve the error message when passing null or undefined to React.cloneElement. (@nicolevy in #12534)

• Fix an IE crash in development when using <StrictMode>. (@bvaughn in #12546)
• Fix labels in User Timing measurements for new component types. (@bvaughn in #12609)
• Improve the warning about wrong component type casing. (@nicolevy in #12533)
• Improve general performance in development mode. (@gaearon in #12537)
• Improve performance of the experimental unstable_observedBits API with nesting. (@gaearon in #12543)

• Add a UMD build. (@bvaughn in #12594)

• Fix a false positive warning in IE11 when using Fragment. (@heikkilamarko in #12504)
• Prefix a private API. (@Andarist in #12501)
• Improve the warning when calling setState() in constructor. (@gaearon in #12532)

• Fix getDerivedStateFromProps() not getting applied in some cases. (@acdlite in #12528)
• Fix a performance regression in development mode. (@gaearon in #12510)
• Fix error handling bugs in development mode. (@gaearon and @acdlite in #12508)
• Improve user timing API messages for profiling. (@flarnie in #12384)

• Set the package version to be in sync with React releases. (@bvaughn in #12526)
• Add a peer dependency on React 16.3+. (@NMinhNguyen in #12496)

• Add a new officially supported context API. (@acdlite in #11818)
• Add a new React.createRef() API as an ergonomic alternative to callback refs. (@trueadm in #12162)
• Add a new React.forwardRef() API to let components forward their refs to a child. (@bvaughn in #12346)
• Fix a false positive warning in IE11 when using React.Fragment. (@XaveScor in #11823)
• Replace React.unstable_AsyncComponent with React.unstable_AsyncMode. (@acdlite in #12117)
• Improve the error message when calling setState() on an unmounted component. (@sophiebits in #12347)

• Add a new getDerivedStateFromProps() lifecycle and UNSAFE_ aliases for the legacy lifecycles. (@bvaughn in #12028)
• Add a new getSnapshotBeforeUpdate() lifecycle. (@bvaughn in #12404)
• Add a new <React.StrictMode> wrapper to help prepare apps for async rendering. (@bvaughn in #12083)
• Add support for onLoad and onError events on the <link> tag. (@roderickhsiao in #11825)
• Add support for noModule boolean attribute on the <script> tag. (@aweary in #11900)
• Fix minor DOM input bugs in IE and Safari. (@nhunzaker in #11534)
• Correctly detect Ctrl + Enter in onKeyPress in more browsers. (@nstraub in #10514)
• Fix containing elements getting focused on SSR markup mismatch. (@koba04 in #11737)
• Fix value and defaultValue to ignore Symbol values. (@nhunzaker in #11741)
• Fix refs to class components not getting cleaned up when the attribute is removed. (@bvaughn in #12178)
• Fix an IE/Edge issue when rendering inputs into a different window. (@M-ZubairAhmed in #11870)
• Throw with a meaningful message if the component runs after jsdom has been destroyed. (@gaearon in #11677)
• Don't crash if there is a global variable called opera with a null value. @alisherdavronov in #11854)
• Don't check for old versions of Opera. (@skiritsis in #11921)
• Deduplicate warning messages about <option selected>. (@watadarkstar in #11821)
• Deduplicate warning messages about invalid callback. (@yenshih in #11833)
• Deprecate ReactDOM.unstable_createPortal() in favor of ReactDOM.createPortal(). (@prometheansacrifice in #11747)
• Don't emit User Timing entries for context types. (@abhaynikam in #12250)
• Improve the error message when context consumer child isn't a function. (@raunofreiberg in #12267)
• Improve the error message when adding a ref to a functional component. (@skiritsis in #11782)

• Prevent an infinite loop when attempting to render portals with SSR. (@gaearon in #11709)
• Warn if a class doesn't extend React.Component. (@wyze in #11993)
• Fix an issue with this.state of different components getting mixed up. (@sophiebits in #12323)
• Provide a better message when component type is undefined. (@HeroProtagonist in #11966)

• Fix handling of fragments in toTree(). (@maciej-ka in #12107 and @gaearon in #12154)
• Shallow renderer should assign state to null for components that don't set it. (@jwbay in #11965)
• Shallow renderer should filter legacy context according to contextTypes. (@koba04 in #11922)
• Add an unstable API for testing asynchronous rendering. (@acdlite in #12478)

• First release of the new package that libraries can use to detect different React node types. (@bvaughn in #12199)
• Add ReactIs.isValidElementType() to help higher-order components validate their inputs. (@jamesreggio in #12483)

• First release of the new package to help library developers target multiple versions of React. (@bvaughn in #12105)

• First release of the new package to subscribe to external data sources safely for async rendering. (@bvaughn in #12325)

• Expose react-reconciler/persistent for building renderers that use persistent data structures. (@gaearon in #12156)
• Pass host context to finalizeInitialChildren(). (@jquense in #11970)
• Remove useSyncScheduling from the host config. (@acdlite in #11771)

• Fix a crash on updates. (@rmhartog in #11955)

• Fix a potential XSS vulnerability when the attacker controls an attribute name (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 in #13302)

• Add Fragment as named export to React. (@clemmy in #10783)
• Support experimental Call/Return types in React.Children utilities. (@MatteoVH in #11422)

• Fix radio buttons not getting checked when using multiple lists of radios. (@landvibe in #11227)
• Fix radio buttons not receiving the onChange event in some cases. (@jquense in #11028)

• Fix setState() callback firing too early when called from componentWillMount. (@accordeiro in #11507)

• Expose react-reconciler/reflection with utilities useful to custom renderers. (@rivenhk in #11683)

• Many tests were rewritten against the public API. Big thanks to everyone who contributed!

• Fix a potential XSS vulnerability when the attacker controls an attribute name (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 in #13302)

• Improve the warning about undefined component type. (@selbekk in #11505)

• Support string values for the capture attribute. (@maxschmeling in #11424)

• Don't freeze the ReactDOMServer public API. (@travi in #11531)
• Don't emit autoFocus={false} attribute on the server. (@gaearon in #11543)

• Change the hydration API for better Flow typing. (@sebmarkbage in #11493)

Starting 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 that mirror npm releases and will continue to be updated.

• Fix an accidental extra global variable in the UMD builds. (@gaearon in #10935)

• Add support for portals in React.Children utilities. (@MatteoVH in #11378)
• Warn when a class has a render method but doesn't extend a known base class. (@sw-yx in #11168)
• Improve the warning when accidentally returning an object from constructor. (@deanbrophy in #11395)

• Allow on as a custom attribute for AMP. (@nuc in #11153)
• Fix onMouseEnter and onMouseLeave firing on wrong elements. (@gaearon in #11164)
• Fix null showing up in a warning instead of the component stack. (@gaearon in #10915)
• Fix IE11 crash in development mode. (@leidegre in #10921)
• Fix tabIndex not getting applied to SVG elements. (@gaearon in #11034)
• Fix SVG children not getting cleaned up on dangerouslySetInnerHTML in IE. (@OriR in #11108)
• Fix false positive text mismatch warning caused by newline normalization. (@gaearon in #11119)
• Fix form.reset() to respect defaultValue on uncontrolled <select>. (@aweary in #11057)
• Fix <textarea> placeholder not rendering on IE11. (@gaearon in #11177)
• Fix a crash rendering into shadow root. (@gaearon in #11037)
• Fix false positive warning about hydrating mixed case SVG tags. (@gaearon in #11174)
• Suppress the new unknown tag warning for <dialog> element. (@gaearon in #11035)
• Warn when defining a non-existent componentDidReceiveProps method. (@iamtommcc in #11479)
• Warn about function child no more than once. (@andreysaleba in #11120)
• Warn about nested updates no more than once. (@anushreesubramani in #11113)
• Deduplicate other warnings about updates. (@anushreesubramani in #11216)
• Include component stack into the warning about contentEditable and children. (@Ethan-Arrowood in #11208)
• Improve the warning about booleans passed to event handlers. (@NicBonetto in #11308)
• Improve the warning when a multiple select gets null value. (@Hendeca in #11141)
• Move link in the warning message to avoid redirect. (@marciovicente in #11400)
• Add a way to suppress the React DevTools installation prompt. (@gaearon in #11448)
• Remove unused code. (@gaearon in #10802, #10803)

• Add a new suppressHydrationWarning attribute for intentional client/server text mismatches. (@sebmarkbage in #11126)
• Fix markup generation when components return strings. (@gaearon in #11109)
• Fix obscure error message when passing an invalid style value. (@iamdustan in #11173)
• Include the autoFocus attribute into SSR markup. (@gaearon in #11192)
• Include the component stack into more warnings. (@gaearon in #11284)

• Fix multiple setState() calls in componentWillMount() in shallow renderer. (@Hypnosphi in #11167)
• Fix shallow renderer to ignore shouldComponentUpdate() after forceUpdate(). (@d4rky-pl in #11239 and #11439)
• Handle forceUpdate() and React.PureComponent correctly. (@koba04 in #11440)
• Add back support for running in production mode. (@gaearon in #11112)
• Add a missing package.json dependency. (@gaearon in #11340)

• Add a missing package.json dependency. (@gaearon in #11341)
• Expose react-art/Circle, react-art/Rectangle, and react-art/Wedge. (@gaearon in #11343)

• First release of the new experimental package for creating custom renderers. (@iamdustan in #10758)
• Add support for React DevTools. (@gaearon in #11463)

• First release of the new experimental package for parent-child communication. (@gaearon in #11364)

• Fix a potential XSS vulnerability when the attacker controls an attribute name (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 in #13302)

• React 16 depends on the collection types Map and Set, as well as 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.

• Components can now return arrays and strings from render. (Docs coming soon!)
• Improved error handling with introduction of "error boundaries". Error boundaries 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.
• First-class support for declaratively rendering a subtree into another DOM node with ReactDOM.createPortal(). (Docs coming soon!)
• Streaming mode for server side rendering is enabled with ReactDOMServer.renderToNodeStream() and ReactDOMServer.renderToStaticNodeStream(). (@aickin in #10425, #10044, #10039, #10024, #9264, and others.)
• React DOM now allows passing non-standard attributes. (@nhunzaker in #10385, 10564, #10495 and others)

• There are several changes to the behavior of scheduling and lifecycle methods:
  • ReactDOM.render() and ReactDOM.unstable_renderIntoContainer() now return null if called from inside a lifecycle method.
    • To work around this, you can either use the new portal API or refs.
  • Minor changes to setState behavior:
    • Calling setState with null no longer triggers an update. This allows you to decide in an updater function if you want to re-render.
    • Calling setState directly in render always causes an update. This was not previously the case. Regardless, you should not be calling setState from render.
    • setState callback (second argument) now fires immediately after componentDidMount / componentDidUpdate instead of after all components have rendered.
  • When replacing <A /> with <B />, B.componentWillMount now always happens before A.componentWillUnmount. Previously, A.componentWillUnmount could fire first in some cases.
  • 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.
  • 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.
  • componentDidUpdate lifecycle no longer receives prevContext param. (@bvaughn in #8631)
  • 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.
  • 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).
  • Shallow renderer does not implement unstable_batchedUpdates() anymore.
  • ReactDOM.unstable_batchedUpdates now only takes one extra argument after the callback.
• The names and paths to the single-file browser builds have changed to emphasize the difference between development and production builds. For example:
  • react/dist/react.js → react/umd/react.development.js
  • react/dist/react.min.js → react/umd/react.production.min.js
  • react-dom/dist/react-dom.js → react-dom/umd/react-dom.development.js
  • react-dom/dist/react-dom.min.js → react-dom/umd/react-dom.production.min.js

• The server renderer has been completely rewritten, with some improvements:
  • 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.
  • 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.
• 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. (@nhunzaker in #10385, 10564, #10495 and others)
• Errors in the render and lifecycle methods now unmount the component tree by default. To prevent this, add error boundaries to the appropriate places in the UI.

• 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.
• 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 and 15.6.0 blog posts for instructions on migrating code and automated codemods.

• Backport support for the new JSX transform to 15.x. (@lunaruan in #18299 and @gaearon in #20024)

• Switch from BSD + Patents to MIT license

• Fix a bug where modifying document.documentMode would trigger IE detection in other browsers, breaking change events. (@aweary in #10032)
• CSS Columns are treated as unitless numbers. (@aweary in #10115)
• Fix bug in QtWebKit when wrapping synthetic events in proxies. (@walrusfruitcake in #10115)
• Prevent event handlers from receiving extra argument in development. (@aweary in #10115)
• Fix cases where onChange would not fire with defaultChecked on radio inputs. (@jquense in #10156)
• Add support for controlList attribute to allowed DOM properties (@nhunzaker in #9940)
• Fix a bug where creating an element with a ref in a constructor did not throw an error in development. (@iansu in #10025)

• Fix a crash on iOS Safari. (@jquense in #9960)
• Don't add px to custom CSS property values. (@TrySound in #9966)

• Downgrade deprecation warnings to use console.warn instead of console.error. (@flarnie in #9753)
• Add a deprecation warning for React.createClass. Points users to create-react-class instead. (@flarnie in #9771)
• Add deprecation warnings and separate module for React.DOM factory helpers. (@nhunzaker in #8356)
• Warn for deprecation of React.createMixin helper, which was never used. (@aweary in #8853)

• Add support for CSS variables in style attribute. (@aweary in #9302)
• Add support for CSS Grid style properties. (@ericsakmar in #9185)
• Fix bug where inputs mutated value on type conversion. (@nhunzaker in #9806)
• Fix issues with onChange not firing properly for some inputs. (@jquense in #8575)
• Fix bug where controlled number input mistakenly allowed period. (@nhunzaker in #9584)
• Fix bug where performance entries were being cleared. (@chrisui in #9451)

• Fix AMD support for addons depending on react. (@flarnie in #9919)
• Fix isMounted() to return true in componentWillUnmount. (@mridgway in #9638)
• Fix react-addons-update to not depend on native Object.assign. (@gaearon in #9937)
• Remove broken Google Closure Compiler annotation from create-react-class. (@gaearon in #9933)
• Remove unnecessary dependency from react-linked-input. (@gaearon in #9766)
• Point react-addons-(css-)transition-group to the new package. (@gaearon in #9937)

• Critical Bugfix: Update the version of prop-types to fix critical bug. (@gaearon in 545c87f)
• Fix react-addons-create-fragment package to include loose-envify transform for Browserify users. (@mridgway in #9642)

• Fix compatibility with Enzyme by exposing batchedUpdates on shallow renderer. (@gaearon in 9382)

Note: this release has a critical issue and was deprecated. Please update to 15.5.4 or higher.

• Fix react-addons-create-fragment package to export correct thing. (@gaearon in #9385)
• Fix create-react-class package to include loose-envify transform for Browserify users. (@mridgway in #9642)

Note: this release has a critical issue and was deprecated. Please update to 15.5.4 or higher.

• Fix the production single-file builds to not include the development code. (@gaearon in #9385)
• Apply better minification to production single-file builds. (@gaearon in #9385)
• Add missing and remove unnecessary dependencies to packages. (@gaearon in #9385)

Note: this release has a critical issue and was deprecated. Please update to 15.5.4 or higher.

• Fix erroneous PropTypes access warning. (@acdlite in (ec97ebb)

Note: this release has a critical issue and was deprecated. Please update to 15.5.4 or higher.

• Added a deprecation warning for React.createClass. Points users to create-react-class instead. (@acdlite in #d9a4fa4)
• Added a deprecation warning for React.PropTypes. Points users to prop-types instead. (@acdlite in #043845c)
• Fixed an issue when using ReactDOM together with ReactDOMServer. (@wacii in #9005)
• Fixed issue with Closure Compiler. (@anmonteiro in #8895)
• Another fix for Closure Compiler. (@Shastel in #8882)
• Added component stack info to invalid element type warning. (@n3tr in #8495)

• Fixed Chrome bug when backspacing in number inputs. (@nhunzaker in #7359)
• Added react-dom/test-utils, which exports the React Test Utils. (@bvaughn)

• Fixed bug where componentWillUnmount was not called for children. (@gre in #8512)
• Added react-test-renderer/shallow, which exports the shallow renderer. (@bvaughn)

• Last release for addons; they will no longer be actively maintained.
• Removed peerDependencies so that addons continue to work indefinitely. (@acdlite and @bvaughn in 8a06cd7 and 67a8db3)
• Updated to remove references to React.createClass and React.PropTypes (@acdlite in 12a96b9)
• react-addons-test-utils is deprecated. Use react-dom/test-utils and react-test-renderer/shallow instead. (@bvaughn)

• Fixed build issues with the Brunch bundler. (@gaearon in #8686)
• Improved error messages for invalid element types. (@sophiebits in #8612)
• Removed a warning about getInitialState when this.state is set. (@bvaughn in #8594)
• Removed some dead code. (@diegomura in #8050, @dfrownfelter in #8597)

• Fixed a decimal point issue on uncontrolled number inputs. (@nhunzaker in #7750)
• Fixed rendering of textarea placeholder in IE11. (@aweary in #8020)
• Worked around a script engine bug in IE9. (@eoin in #8018)

• Fixed build issues in RequireJS and SystemJS environments. (@gaearon in #8686)
• Added missing package dependencies. (@kweiberth in #8467)

• Restructure variable assignment to work around a Rollup bug (@gaearon in #8384)

• Fixed event handling on disabled button elements (@sophiebits in #8387)
• Fixed compatibility of browser build with AMD environments (@zpao in #8374)

• React package and browser build no longer "secretly" includes React DOM. (@sebmarkbage in #7164 and #7168)
• Required PropTypes now fail with specific messages for null and undefined. (@chenglou in #7291)
• Improved development performance by freezing children instead of copying. (@keyanzhang in #7455)

• Fixed occasional test failures when React DOM is used together with shallow renderer. (@goatslacker in #8097)
• Added a warning for invalid aria- attributes. (@jessebeach in #7744)
• Added a warning for using autofocus rather than autoFocus. (@hkal in #7694)
• Removed an unnecessary warning about polyfilling String.prototype.split. (@nhunzaker in #7629)
• Clarified the warning about not calling PropTypes manually. (@jedwards1211 in #7777)
• The unstable batchedUpdates API now passes the wrapped function's return value through. (@bgnorlov in #7444)
• Fixed a bug with updating text in IE 8. (@mnpenner in #7832)

• When ReactPerf is started, you can now view the relative time spent in components as a chart in Chrome Timeline. (@gaearon in #7549)

• If you call Simulate.click() on a <input disabled onClick={foo} /> then foo will get called whereas it didn't before. (@nhunzaker in #7642)

• Due to packaging changes, it no longer crashes when imported together with React DOM in the same file. (@sebmarkbage in #7164 and #7168)
• ReactTestRenderer.create() now accepts {createNodeMock: element => mock} as an optional argument so you can mock refs with snapshot testing. (@Aweary in #7649, #8261)

• Remove plain object warning from React.createElement & React.cloneElement. (@spudly in #7724)

• Add playsInline to supported HTML attributes. (@reaperhulk in #7519)
• Add as to supported HTML attributes. (@kevinslin in #7582)
• Improve DOM nesting validation warning about whitespace. (@sophiebits in #7515)
• Avoid "Member not found" exception in IE10 when calling preventDefault() in Synthetic Events. (@g-palmer in #7411)
• Fix memory leak in onSelect implementation. (@AgtLucas in #7533)
• Improve robustness of document.documentMode checks to handle Google Tag Manager. (@SchleyB in #7594)
• Add more cases to controlled inputs warning. (@marcin-mazurek in #7544)
• Handle case of popup blockers overriding document.createEvent. (@Andarist in #7621)
• Fix issue with dangerouslySetInnerHTML and SVG in Internet Explorer. (@zpao in #7618)
• Improve handling of Japanese IME on Internet Explorer. (@msmania in #7107)

• Support error boundaries. (@millermedeiros in #7558, #7569, #7619)
• Skip null ref warning. (@Aweary in #7658)

• Ensure lifecycle timers are stopped on errors. (@gaearon in #7548)

• Improve performance of development builds in various ways. (@gaearon in #7461, #7463, #7483, #7488, #7491, #7510)
• Cleanup internal hooks to improve performance of development builds. (@gaearon in #7464, #7472, #7481, #7496)
• Upgrade fbjs to pick up another performance improvement from @gaearon for development builds. (@zpao in #7532)
• Improve startup time of React in Node. (@zertosh in #7493)
• Improve error message of React.Children.only. (@sophiebits in #7514)

• Avoid <input> validation warning from browsers when changing type. (@nhunzaker in #7333)
• Avoid "Member not found" exception in IE10 when calling stopPropagation() in Synthetic Events. (@nhunzaker in #7343)
• Fix issue resulting in inability to update some <input> elements in mobile browsers. (@keyanzhang in #7397)
• Fix memory leak in server rendering. (@keyanzhang in #7410)
• Fix issue resulting in <input type="range"> values not updating when changing min or max. (@troydemonbreun in #7486)
• Add new warning for rare case of attempting to unmount a container owned by a different copy of React. (@ventuno in #7456)

• Fix ReactTestInstance::toJSON() with empty top-level components. (@Morhaus in #7523)

• Change trackedTouchCount invariant into a console.error for better reliability. (@yungsters in #7400)

• 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 in #7195)
• Add new warning when modifying this.props.children. (@jimfb in #7001)
• Fixed issue with ref resolution order. (@gaearon in #7101)
• Warn when mixin is undefined. (@swaroopsm in #6158)
• Downgrade "unexpected batch number" invariant to a warning. (@sophiebits in #7133)
• Validate arguments to oneOf and oneOfType PropTypes sooner. (@troydemonbreun in #6316)
• Warn when calling PropTypes directly. (@Aweary in #7132, #7194)
• Improve warning when using Maps as children. (@keyanzhang in #7260)
• Add additional type information to the PropTypes.element warning. (@alexzherdev in #7319)
• Improve component identification in no-op setState warning. (@keyanzhang in #7326)

• Fix issue with nested server rendering. (@Aweary in #7033)
• Add xmlns, xmlnsXlink to supported SVG attributes. (@salzhrani in #6471)
• Add referrerPolicy to supported HTML attributes. (@Aweary in #7274)
• Fix issue resulting in <input type="range"> initial value being rounded. (@troydemonbreun in #7251)

• Initial public release of package allowing more focused testing. Install with npm install react-test-renderer. (@sophiebits in #6944, #7258, @iamdustan in #7362)

• Fix issue resulting in excessive warnings when encountering an internal measurement error. (@sassanh in #7299)

• Implement type property on for events created via TestUtils.Simulate.*. (@yaycmyk in #6154)
• Fix crash when running TestUtils with the production build of React. (@gaearon in #7246)

• Fix errant warning about missing React element. (@gaearon in #7193)
• Better removal of dev-only code, leading to a small reduction in the minified production bundle size. (@gaearon in #7188, #7189)

• Add stack trace to null input value warning. (@jimfb in #7040)
• Fix webcomponents example. (@jalexanderfox in #7057)
• Fix unstable_renderSubtreeIntoContainer so that context properly updates when linked to state. (@gaearon in #7125)
• Improve invariant wording for void elements. (@starkch in #7066)
• Ensure no errors are thrown due to event handlers in server rendering. (@rricard in #7127)
• Fix regression resulting in value-less submit and reset inputs removing the browser-default text. (@zpao in #7197)
• Fix regression resulting in empty name attribute being added to inputs when not provided. (@okonet in #7199)
• Fix issue with nested server rendering. (@Aweary in #7033)

• Make ReactPerf.start() work properly during lifecycle methods. (@gaearon in #7208).

• Fix issue resulting in spurious unknown property warnings. (@batusai513 in #7165)

• Improve error handling in cross-platform touch event handling. (@yungsters in #7143)

• Add error codes to production invariants, with links to the view the full error text. (@keyanzhang in #6948)
• Include component stack information in PropType validation warnings. (@troydemonbreun in #6398, @sophiebits in #6771)
• Include component stack information in key warnings. (@keyanzhang in #6799)
• Stop validating props at mount time, only validate at element creation. (@keyanzhang in #6824)
• New invariant providing actionable error in missing instance case. (@yungsters in #6990)
• Add React.PropTypes.symbol to support ES2015 Symbols as props. (@puradox in #6377)
• Fix incorrect coercion of ref or key that are undefined in development (@gaearon in #6880)
• Fix a false positive when passing other element’s props to cloneElement (@ericmatthys in #6268)
• Warn if you attempt to define childContextTypes on a functional component (@Aweary in #6933)

• Add warning for unknown properties on DOM elements. (@jimfb in #6800, @gm758 in #7152)
• Properly remove attributes from custom elements. (@grassator in #6748)
• Fix invalid unicode escape in attribute name regular expression. (@nbjahan in #6772)
• Add onLoad handling to <link> element. (@roderickhsiao in #6815)
• Add onError handling to <source> element. (@wadahiro in #6941)
• Handle value and defaultValue more accurately in the DOM. (@jimfb in #6406)
• Fix events issue in environments with mutated Object.prototype. (@Weizenlol in #6886)
• Fix issue where is="null" ended up in the DOM in Firefox. (@darobin in #6896)
• Improved performance of text escaping by using escape-html. (@aickin in #6862)
• Fix issue with dangerouslySetInnerHTML and SVG in Internet Explorer. (@joshhunt in #6982)
• Fix issue with <textarea> placeholders. (@jimfb in #7002)
• Fix controlled vs uncontrolled detection of <input type="radio"/>. (@jimfb in #7003)
• Improve performance of updating text content. (@trueadm in #7005)
• Ensure controlled <select> components behave the same on initial render as they do on updates. (@yiminghe in #5362)

• Add isRunning() API. (@nfcampos in #6763)
• Improve accuracy of lifecycle hook timing. (@gaearon in #6858)
• Fix internal errors when using ReactPerf with portal components. (@gaearon in #6860)
• Fix performance regression. (@sophiebits in #6770)
• Add warning that ReactPerf is not enabled in production. (@sashashakun in #6884)

• Fix timing issue with null node. (@keyanzhang in #6958)

• Dependencies on React Native modules use CommonJS requires instead of providesModule. (@davidaurelio in #6715)

• Ensure we're using the latest object-assign, which has protection against a non-spec-compliant native Object.assign. (@zpao in #6681)
• Add a new warning to communicate that props objects passed to createElement must be plain objects. (@richardscarrott in #6134)
• Fix a batching bug resulting in some lifecycle methods incorrectly being called multiple times. (@sophiebits in #6650)

• Fix regression in custom elements support. (@jscissr in #6570)
• Stop incorrectly warning about using onScroll event handler with server rendering. (@Aweary in #6678)
• Fix grammar in the controlled input warning. (@jakeboone02 in #6657)
• Fix issue preventing <object> nodes from being able to read <param> nodes in IE. (@syranide in #6691)
• Fix issue resulting in crash when using experimental error boundaries with server rendering. (@jimfb in #6694)
• Add additional information to the controlled input warning. (@borisyankov in #6341)

• Completely rewritten to collect data more accurately and to be easier to maintain. (@gaearon in #6647, #6046)

• Remove some special cases for platform specific branching. (@sebmarkbage in #6660)
• Remove use of merge utility. (@sebmarkbage in #6634)
• Renamed some modules to better indicate usage (@javache in #6643)

• Removed extraneous files from npm package. (@gaearon in #6388)
• Ensure componentWillUnmount is only called once. (@jimfb in #6613)

• Fixed bug resulting in disabled buttons responding to mouse events in IE. (@nhunzaker in #6215)
• Ensure <option>s are correctly selected when inside <optgroup>. (@trevorsmith in #6442)
• Restore support for rendering into a shadow root. (@Wildhoney in #6462)
• Ensure nested <body> elements are caught when warning for invalid markup. (@keyanzhang in #6469)
• Improve warning when encountering multiple elements with the same key. (@hkal in #6500)

• Ensure that functional components do not have an owner. (@gaearon in #6362)
• Handle invalid arguments to scryRenderedDOMComponentsWithClass better. (@ipeters90 in #6529)

• Ignore DOM operations that occur outside the batch operation. (@gaearon in #6516)

• These files are now shipped inside the React npm package. They have no impact on React core or ReactDOM.

• Restore React.__spread API to unbreak code compiled with some tools making use of this undocumented API. It is now officially deprecated. (@zpao in #6444)

• Fixed issue resulting in loss of cursor position in controlled inputs. (@sophiebits in #6449)

• Initial render now uses document.createElement instead of generating HTML. Previously we would generate a large string of HTML and then set node.innerHTML. At the time, this was decided to be faster than using document.createElement for the majority of cases and browsers that we supported. Browsers have continued to improve and so overwhelmingly this is no longer true. By using createElement we can make other parts of React faster. (@sophiebits in #5205)
• data-reactid is no longer on every node. As a result of using document.createElement, we can prime the node cache as we create DOM nodes, allowing us to skip a potential lookup (which used the data-reactid attribute). Root nodes will have a data-reactroot attribute and server generated markup will still contain data-reactid. (@sophiebits in #5205)
• No more extra <span>s. ReactDOM will now render plain text nodes interspersed with comment nodes that are used for demarcation. This gives us the same ability to update individual pieces of text, without creating extra nested nodes. If you were targeting these <span>s in your CSS, you will need to adjust accordingly. You can always render them explicitly in your components. (@mwiencek in #5753)
• Rendering null now uses comment nodes. Previously null would render to <noscript> elements. We now use comment nodes. This may cause issues if making use of :nth-child CSS selectors. While we consider this rendering behavior an implementation detail of React, it's worth noting the potential problem. (@sophiebits in #5451)
• Functional components can now return null. We added support for defining stateless components as functions in React 0.14. However, React 0.14 still allowed you to define a class component without extending React.Component or using React.createClass(), so we couldn’t reliably tell if your component is a function or a class, and did not allow returning null from it. This issue is solved in React 15, and you can now return null from any component, whether it is a class or a function. (@jimfb in #5884)
• Improved SVG support. All SVG tags are now fully supported. (Uncommon SVG tags are not present on the React.DOM element helper, but JSX and React.createElement work on all tag names.) All SVG attributes that are implemented by the browsers should be supported too. If you find any attributes that we have missed, please let us know in this issue. (@zpao in #6243)

• No more extra <span>s.
• React.cloneElement() now resolves defaultProps. We fixed a bug in React.cloneElement() that some components may rely on. If some of the props received by cloneElement() are undefined, it used to return an element with undefined values for those props. We’re changing it to be consistent with createElement(). Now any undefined props passed to cloneElement() are resolved to the corresponding component’s defaultProps. (@truongduy134 in #5997)
• ReactPerf.getLastMeasurements() is opaque. This change won’t affect applications but may break some third-party tools. We are revamping ReactPerf implementation and plan to release it during the 15.x cycle. The internal performance measurement format is subject to change so, for the time being, we consider the return value of ReactPerf.getLastMeasurements() an opaque data structure that should not be relied upon. (@gaearon in #6286)

These deprecations were introduced nine months ago in v0.14 with a warning and are removed:

• Deprecated APIs are removed from the React top-level export: findDOMNode, render, renderToString, renderToStaticMarkup, and unmountComponentAtNode. As a reminder, they are now available on ReactDOM and ReactDOMServer. (@jimfb in #5832)
• Deprecated addons are removed: batchedUpdates and cloneWithProps. (@jimfb in #5859, @zpao in #6016)
• Deprecated component instance methods are removed: setProps, replaceProps, and getDOMNode. (@jimfb in #5570)
• Deprecated CommonJS react/addons entry point is removed. As a reminder, you should use separate react-addons-* packages instead. This only applies if you use the CommonJS builds. (@gaearon in #6285)
• Passing children to void elements like <input> was deprecated, and now throws an error. (@jonhester in #3372)
• React-specific properties on DOM refs (e.g. this.refs.div.props) were deprecated, and are removed now. (@jimfb in #5495)

Each of these changes will continue to work as before with a new warning until the release of React 16 so you can upgrade your code gradually.

• LinkedStateMixin and valueLink are now deprecated due to very low popularity. If you need this, you can use a wrapper component that implements the same behavior: react-linked-input. (@jimfb in #6127)
• Future versions of React will treat <input value={null}> as a request to clear the input. However, React 0.14 has been ignoring value={null}. React 15 warns you on a null input value and offers you to clarify your intention. To fix the warning, you may explicitly pass an empty string to clear a controlled input, or pass undefined to make the input uncontrolled. (@antoaravinth in #5048)
• ReactPerf.printDOM() was renamed to ReactPerf.printOperations(), and ReactPerf.getMeasurementsSummaryMap() was renamed to ReactPerf.getWasted(). (@gaearon in #6287)

• If you use a minified copy of the development build, React DOM kindly encourages you to use the faster production build instead. (@sophiebits in #5083)
• React DOM: When specifying a unit-less CSS value as a string, a future version will not add px automatically. This version now warns in this case (ex: writing style={{width: '300'}}. Unitless number values like width: 300 are unchanged. (@pluma in #5140)
• Synthetic Events will now warn when setting and accessing properties (which will not get cleared appropriately), as well as warn on access after an event has been returned to the pool. (@kentcdodds in #5940 and @koba04 in #5947)
• Elements will now warn when attempting to read ref and key from the props. (@prometheansacrifice in #5744)
• React will now warn if you pass a different props object to super() in the constructor. (@prometheansacrifice in #5346)
• React will now warn if you call setState() inside getChildContext(). (@raineroviir in #6121)
• React DOM now attempts to warn for mistyped event handlers on DOM elements, such as onclick which should be onClick. (@ali in #5361)
• React DOM now warns about NaN values in style. (@jontewks in #5811)
• React DOM now warns if you specify both value and defaultValue for an input. (@mgmcdermott in #5823)
• React DOM now warns if an input switches between being controlled and uncontrolled. (@TheBlasfem in #5864)
• React DOM now warns if you specify onFocusIn or onFocusOut handlers as they are unnecessary in React. (@jontewks in #6296)
• React now prints a descriptive error message when you pass an invalid callback as the last argument to ReactDOM.render(), this.setState(), or this.forceUpdate(). (@conorhastings in #5193 and @gaearon in #6310)
• Add-Ons: TestUtils.Simulate() now prints a helpful message if you attempt to use it with shallow rendering. (@conorhastings in #5358)
• PropTypes: arrayOf() and objectOf() provide better error messages for invalid arguments. (@chicoxyzzy in #5390)

• Fixed multiple small memory leaks. (@sophiebits in #4983 and @victor-homyakov in #6309)
• Input events are handled more reliably in IE 10 and IE 11; spurious events no longer fire when using a placeholder. (@jquense in #4051)
• The componentWillReceiveProps() lifecycle method is now consistently called when context changes. (@milesj in #5787)
• React.cloneElement() doesn’t append slash to an existing key when used inside React.Children.map(). (@ianobermiller in #5892)
• React DOM now supports the cite and profile HTML attributes. (@AprilArcus in #6094 and @saiichihashimoto in #6032)
• React DOM now supports cssFloat, gridRow and gridColumn CSS properties. (@stevenvachon in #6133 and @mnordick in #4779)
• React DOM now correctly handles borderImageOutset, borderImageWidth, borderImageSlice, floodOpacity, strokeDasharray, and strokeMiterlimit as unitless CSS properties. (@rofrischmann in #6210 and #6270)
• React DOM now supports the onAnimationStart, onAnimationEnd, onAnimationIteration, onTransitionEnd, and onInvalid events. Support for onLoad has been added to object elements. (@tomduncalf in #5187, @milesj in #6005, and @ara4n in #5781)
• React DOM now defaults to using DOM attributes instead of properties, which fixes a few edge case bugs. Additionally the nullification of values (ex: href={null}) now results in the forceful removal, no longer trying to set to the default value used by browsers in the absence of a value. (@syranide in #1510)
• React DOM does not mistakenly coerce children to strings for Web Components. (@jimfb in #5093)
• React DOM now correctly normalizes SVG <use> events. (@edmellum in #5720)
• React DOM does not throw if a <select> is unmounted while its onChange handler is executing. (@sambev in #6028)
• React DOM does not throw in Windows 8 apps. (@Andrew8xx8 in #6063)
• React DOM does not throw when asynchronously unmounting a child with a ref. (@yiminghe in #6095)
• React DOM no longer forces synchronous layout because of scroll position tracking. (@syranide in #2271)
• Object.is is used in a number of places to compare values, which leads to fewer false positives, especially involving NaN. In particular, this affects the shallowCompare add-on. (@chicoxyzzy in #6132)
• Add-Ons: ReactPerf no longer instruments adding or removing an event listener because they don’t really touch the DOM due to event delegation. (@antoaravinth in #5209)

• React now uses loose-envify instead of envify so it installs fewer transitive dependencies. (@qerub in #6303)
• Shallow renderer now exposes getMountedInstance(). (@glenjamin in #4918)
• Shallow renderer now returns the rendered output from render(). (@simonewebdesign in #5411)
• React no longer depends on ES5 shams for Object.create and Object.freeze in older environments. It still, however, requires ES5 shims in those environments. (@dgreensp in #4959)
• React DOM now allows data- attributes with names that start with numbers. (@nLight in #5216)
• React DOM adds a new suppressContentEditableWarning prop for components like Draft.js that intentionally manage contentEditable children with React. (@mxstbr in #6112)
• React improves the performance for createClass() on complex specs. (@sophiebits in #5550)

• Backport support for the new JSX transform to 0.14.x. (@lunaruan in #18299 and @gaearon in #20024)

• Fixed memory leak when rendering on the server

• Fixed bug with <option> tags when using dangerouslySetInnerHTML
• Fixed memory leak in synthetic event system

• Fixed bug with calling setState in componentWillMount when using shallow rendering

• Updated fbjs dependency to pick up change affecting handling of undefined document.

• More minor internal changes for better compatibility with React Native

• Minor internal changes for better compatibility with React Native

• The autoCapitalize and autoCorrect props are now set as attributes in the DOM instead of properties to improve cross-browser compatibility
• Fixed bug with controlled <select> elements not handling updates properly

• Some DOM operation names have been updated for clarity in the output of .printDOM()

• Added support for nonce attribute for <script> and <style> elements
• Added support for reversed attribute for <ol> elements

• Fixed bug with shallow rendering and function refs

• Fixed bug resulting in timeouts firing incorrectly when mounting and unmounting rapidly

• Added react-dom-server.js to expose renderToString and renderToStaticMarkup for usage in the browser

• Fixed bug with development build preventing events from firing in some versions of Internet Explorer & Edge
• Fixed bug with development build when using es5-sham in older versions of Internet Explorer
• Added support for integrity attribute
• Fixed bug resulting in children prop being coerced to a string for custom elements, which was not the desired behavior
• Moved react from dependencies to peerDependencies to match expectations and align with react-addons-* packages

• Fixed bug where events wouldn't fire in old browsers when using React in development mode
• Fixed bug preventing use of dangerouslySetInnerHTML with Closure Compiler Advanced mode
• Added support for srcLang, default, and kind attributes for <track> elements
• Added support for color attribute
• Ensured legacy .props access on DOM nodes is updated on re-renders

• Fixed scryRenderedDOMComponentsWithClass so it works with SVG

• Fix bug preventing 0 to be used as a timeout value

• Added react-dom.js to main to improve compatibility with tooling

• Split the main react package into two: react and react-dom. This paves the way to writing components that can be shared between the web version of React and React Native. This means you will need to include both files and some functions have been moved from React to ReactDOM.
• Addons have been moved to separate packages (react-addons-clone-with-props, react-addons-create-fragment, react-addons-css-transition-group, react-addons-linked-state-mixin, react-addons-perf, react-addons-pure-render-mixin, react-addons-shallow-compare, react-addons-test-utils, react-addons-transition-group, react-addons-update, ReactDOM.unstable_batchedUpdates).
• Stateless functional components - React components were previously created using React.createClass or using ES6 classes. This release adds a new syntax where a user defines a single stateless render function (with one parameter: props) which returns a JSX element, and this function may be used as a component.
• Refs to DOM components as the DOM node itself. Previously the only useful thing you can do with a DOM component is call getDOMNode() to get the underlying DOM node. Starting with this release, a ref to a DOM component is the actual DOM node. Note that refs to custom (user-defined) components work exactly as before; only the built-in DOM components are affected by this change.

• React.initializeTouchEvents is no longer necessary and has been removed completely. Touch events now work automatically.
• Add-Ons: Due to the DOM node refs change mentioned above, TestUtils.findAllInRenderedTree and related helpers are no longer able to take a DOM component, only a custom component.
• The props object is now frozen, so mutating props after creating a component element is no longer supported. In most cases, React.cloneElement should be used instead. This change makes your components easier to reason about and enables the compiler optimizations mentioned above.
• Plain objects are no longer supported as React children; arrays should be used instead. You can use the createFragment helper to migrate, which now returns an array.
• Add-Ons: classSet has been removed. Use classnames instead.
• Web components (custom elements) now use native property names. Eg: class instead of className.

• this.getDOMNode() is now deprecated and ReactDOM.findDOMNode(this) can be used instead. Note that in the common case, findDOMNode is now unnecessary since a ref to the DOM component is now the actual DOM node.
• setProps and replaceProps are now deprecated. Instead, call ReactDOM.render again at the top level with the new props.
• ES6 component classes must now extend React.Component in order to enable stateless function components. The ES3 module pattern will continue to work.
• Reusing and mutating a style object between renders has been deprecated. This mirrors our change to freeze the props object.
• Add-Ons: cloneWithProps is now deprecated. Use React.cloneElement instead (unlike cloneWithProps, cloneElement does not merge className or style automatically; you can merge them manually if needed).
• Add-Ons: To improve reliability, CSSTransitionGroup will no longer listen to transition events. Instead, you should specify transition durations manually using props such as transitionEnterTimeout={500}.

• Added React.Children.toArray which takes a nested children object and returns a flat array with keys assigned to each child. This helper makes it easier to manipulate collections of children in your render methods, especially if you want to reorder or slice this.props.children before passing it down. In addition, React.Children.map now returns plain arrays too.
• React uses console.error instead of console.warn for warnings so that browsers show a full stack trace in the console. (Our warnings appear when you use patterns that will break in future releases and for code that is likely to behave unexpectedly, so we do consider our warnings to be “must-fix” errors.)
• Previously, including untrusted objects as React children could result in an XSS security vulnerability. This problem should be avoided by properly validating input at the application layer and by never passing untrusted objects around your application code. As an additional layer of protection, React now tags elements with a specific ES2015 (ES6) Symbol in browsers that support it, in order to ensure that React never considers untrusted JSON to be a valid element. If this extra security protection is important to you, you should add a Symbol polyfill for older browsers, such as the one included by Babel’s polyfill.
• When possible, React DOM now generates XHTML-compatible markup.
• React DOM now supports these standard HTML attributes: capture, challenge, inputMode, is, keyParams, keyType, minLength, summary, wrap. It also now supports these non-standard attributes: autoSave, results, security.
• React DOM now supports these SVG attributes, which render into namespaced attributes: xlinkActuate, xlinkArcrole, xlinkHref, xlinkRole, xlinkShow, xlinkTitle, xlinkType, xmlBase, xmlLang, xmlSpace.
• The image SVG tag is now supported by React DOM.
• In React DOM, arbitrary attributes are supported on custom elements (those with a hyphen in the tag name or an is="..." attribute).
• React DOM now supports these media events on audio and video tags: onAbort, onCanPlay, onCanPlayThrough, onDurationChange, onEmptied, onEncrypted, onEnded, onError, onLoadedData, onLoadedMetadata, onLoadStart, onPause, onPlay, onPlaying, onProgress, onRateChange, onSeeked, onSeeking, onStalled, onSuspend, onTimeUpdate, onVolumeChange, onWaiting.
• Many small performance improvements have been made.
• Many warnings show more context than before.
• Add-Ons: A shallowCompare add-on has been added as a migration path for PureRenderMixin in ES6 classes.
• Add-Ons: CSSTransitionGroup can now use custom class names instead of appending -enter-active or similar to the transition name.

• React DOM now warns you when nesting HTML elements invalidly, which helps you avoid surprising errors during updates.
• Passing document.body directly as the container to ReactDOM.render now gives a warning as doing so can cause problems with browser extensions that modify the DOM.
• Using multiple instances of React together is not supported, so we now warn when we detect this case to help you avoid running into the resulting problems.

• Click events are handled by React DOM more reliably in mobile browsers, particularly in Mobile Safari.
• SVG elements are created with the correct namespace in more cases.
• React DOM now renders <option> elements with multiple text children properly and renders <select> elements on the server with the correct option selected.
• When two separate copies of React add nodes to the same document (including when a browser extension uses React), React DOM tries harder not to throw exceptions during event handling.
• Using non-lowercase HTML tag names in React DOM (e.g., React.createElement('DIV')) no longer causes problems, though we continue to recommend lowercase for consistency with the JSX tag name convention (lowercase names refer to built-in components, capitalized names refer to custom components).
• React DOM understands that these CSS properties are unitless and does not append “px” to their values: animationIterationCount, boxOrdinalGroup, flexOrder, tabSize, stopOpacity.
• Add-Ons: When using the test utils, Simulate.mouseEnter and Simulate.mouseLeave now work.
• Add-Ons: ReactTransitionGroup now correctly handles multiple nodes being removed simultaneously.

• The react-tools package and JSXTransformer.js browser file have been deprecated. You can continue using version 0.13.3 of both, but we no longer support them and recommend migrating to Babel, which has built-in support for React and JSX.

• Babel 5.8.24 introduces Inlining React elements: The optimisation.react.inlineElements transform converts JSX elements to object literals like {type: 'div', props: ...} instead of calls to React.createElement. This should only be enabled in production, since it disables some development warnings/checks.
• Babel 5.8.24 introduces Constant hoisting for React elements: The optimisation.react.constantElements transform hoists element creation to the top level for subtrees that are fully static, which reduces calls to React.createElement and the resulting allocations. More importantly, it tells React that the subtree hasn’t changed so React can completely skip it when reconciling. This should only be enabled in production, since it disables some development warnings/checks.

• Added clipPath element and attribute for SVG
• Improved warnings for deprecated methods in plain JS classes

• Loosened dangerouslySetInnerHTML restrictions so {__html: undefined} will no longer throw
• Fixed extraneous context warning with non-pure getChildContext
• Ensure replaceState(obj) retains prototype of obj

• Test Utils: Ensure that shallow rendering works when components define contextTypes

• Added strokeDashoffset, flexPositive, flexNegative to the list of unitless CSS properties
• Added support for more DOM properties:
  • scoped - for <style> elements
  • high, low, optimum - for <meter> elements
  • unselectable - IE-specific property to prevent user selection

• Fixed a case where re-rendering after rendering null didn't properly pass context
• Fixed a case where re-rendering after rendering with style={null} didn't properly update style
• Update uglify dependency to prevent a bug in IE8
• Improved warnings

• Immutability Helpers: Ensure it supports hasOwnProperty as an object key

• Improve documentation for new options

• Don't throw when rendering empty <select> elements
• Ensure updating style works when transitioning from null

• TestUtils: Don't warn about getDOMNode for ES6 classes
• TestUtils: Ensure wrapped full page components (<html>, <head>, <body>) are treated as DOM components
• Perf: Stop double-counting DOM components

• Fix option parsing for --non-strict-es6module

• Deprecated patterns that warned in 0.12 no longer work: most prominently, calling component classes without using JSX or React.createElement and using non-component functions with JSX or createElement
• Mutating props after an element is created is deprecated and will cause warnings in development mode; future versions of React will incorporate performance optimizations assuming that props aren't mutated
• Static methods (defined in statics) are no longer autobound to the component class
• ref resolution order has changed slightly such that a ref to a component is available immediately after its componentDidMount method is called; this change should be observable only if your component calls a parent component's callback within your componentDidMount, which is an anti-pattern and should be avoided regardless
• Calls to setState in life-cycle methods are now always batched and therefore asynchronous. Previously the first call on the first mount was synchronous.
• setState and forceUpdate on an unmounted component now warns instead of throwing. That avoids a possible race condition with Promises.
• Access to most internal properties has been completely removed, including this._pendingState and this._rootNodeID.

• Support for using ES6 classes to build React components; see the v0.13.0 beta 1 notes for details.
• Added new top-level API React.findDOMNode(component), which should be used in place of component.getDOMNode(). The base class for ES6-based components will not have getDOMNode. This change will enable some more patterns moving forward.
• Added a new top-level API React.cloneElement(el, props) for making copies of React elements – see the v0.13 RC2 notes for more details.
• New ref style, allowing a callback to be used in place of a name: <Photo ref={(c) => this._photo = c} /> allows you to reference the component with this._photo (as opposed to ref="photo" which gives this.refs.photo).
• this.setState() can now take a function as the first argument for transactional state updates, such as this.setState((state, props) => ({count: state.count + 1})); – this means that you no longer need to use this._pendingState, which is now gone.
• Support for iterators and immutable-js sequences as children.

• ComponentClass.type is deprecated. Just use ComponentClass (usually as element.type === ComponentClass).
• Some methods that are available on createClass-based components are removed or deprecated from ES6 classes (getDOMNode, replaceState, isMounted, setProps, replaceProps).

• React.addons.createFragment was added for adding keys to entire sets of children.

• React.addons.classSet is now deprecated. This functionality can be replaced with several freely available modules. classnames is one such module.
• Calls to React.addons.cloneWithProps can be migrated to use React.cloneElement instead – make sure to merge style and className manually if desired.

• When transforming ES6 syntax, class methods are no longer enumerable by default, which requires Object.defineProperty; if you support browsers such as IE8, you can pass --target es3 to mirror the old behavior

• --target option is available on the jsx command, allowing users to specify and ECMAScript version to target.
  • es5 is the default.
  • es3 restores the previous default behavior. An additional transform is added here to ensure the use of reserved words as properties is safe (eg this.static will become this['static'] for IE8 compatibility).
• The transform for the call spread operator has also been enabled.

• The return value of transform now contains sourceMap as a JS object already, not an instance of SourceMapGenerator.

• A change was made to how some JSX was parsed, specifically around the use of > or } when inside an element. Previously it would be treated as a string but now it will be treated as a parse error. The jsx_orphaned_brackets_transformer package on npm can be used to find and fix potential issues in your JSX code.

• Added support for more HTML attributes: formAction, formEncType, formMethod, formTarget, marginHeight, marginWidth
• Added strokeOpacity to the list of unitless CSS properties
• Removed trailing commas (allows npm module to be bundled and used in IE8)
• Fixed bug resulting in error when passing undefined to React.createElement - now there is a useful warning

• JSX-related transforms now always use double quotes for props and displayName

• Types transform updated with latest support
• jstransform version updated with improved ES6 transforms
• Explicit Esprima dependency removed in favor of using Esprima information exported by jstransform

• key and ref moved off props object, now accessible on the element directly
• React is now BSD licensed with accompanying Patents grant
• Default prop resolution has moved to Element creation time instead of mount time, making them effectively static
• React.__internals is removed - it was exposed for DevTools which no longer needs access
• Composite Component functions can no longer be called directly - they must be wrapped with React.createFactory first. This is handled for you when using JSX.

• Spread operator ({...}) introduced to deprecate this.transferPropsTo
• Added support for more HTML attributes: acceptCharset, classID, manifest

• React.renderComponent --> React.render
• React.renderComponentToString --> React.renderToString
• React.renderComponentToStaticMarkup --> React.renderToStaticMarkup
• React.isValidComponent --> React.isValidElement
• React.PropTypes.component --> React.PropTypes.element
• React.PropTypes.renderable --> React.PropTypes.node
• DEPRECATED React.isValidClass
• DEPRECATED instance.transferPropsTo
• DEPRECATED Returning false from event handlers to preventDefault
• DEPRECATED Convenience Constructor usage as function, instead wrap with React.createFactory
• DEPRECATED use of key={null} to assign implicit keys

• Better handling of events and updates in nested results, fixing value restoration in "layered" controlled components
• Correctly treat event.getModifierState as case sensitive
• Improved normalization of event.charCode
• Better error stacks when involving autobound methods
• Removed DevTools message when the DevTools are installed
• Correctly detect required language features across browsers
• Fixed support for some HTML attributes:
  • list updates correctly now
  • scrollLeft, scrollTop removed, these should not be specified as props
• Improved error messages

• React.addons.batchedUpdates added to API for hooking into update cycle

• React.addons.update uses assign instead of copyProperties which does hasOwnProperty checks. Properties on prototypes will no longer be updated correctly.

• Fixed some issues with CSS Transitions

• Enforced convention: lower case tag names are always treated as HTML tags, upper case tag names are always treated as composite components
• JSX no longer transforms to simple function calls

• @jsx React.DOM no longer required
• spread ({...}) operator introduced to allow easier use of props

• JSXTransformer: Make sourcemaps an option when using APIs directly (eg, for react-rails)

• Added support for <dialog> element and associated open attribute
• Added support for <picture> element and associated media and sizes attributes
• Added React.createElement API in preparation for React v0.12
  • React.createDescriptor has been deprecated as a result

• <picture> is now parsed into React.DOM.picture

• Update esprima and jstransform for correctness fixes
• The jsx executable now exposes a --strip-types flag which can be used to remove TypeScript-like type annotations
  • This option is also exposed to require('react-tools').transform as stripTypes

• setState can be called inside componentWillMount in non-DOM environments
• SyntheticMouseEvent.getEventModifierState correctly renamed to getModifierState
• getModifierState correctly returns a boolean
• getModifierState is now correctly case sensitive
• Empty Text node used in IE8 innerHTML workaround is now removed, fixing rerendering in certain cases

• Fix duplicate variable declaration in JSXTransformer (caused issues in some browsers)

• getDefaultProps() is now called once per class and shared across all instances
• MyComponent() now returns a descriptor, not an instance
• React.isValidComponent and React.PropTypes.component validate descriptors, not component instances
• Custom propType validators should return an Error instead of logging directly

• Rendering to null
• Keyboard events include normalized e.key and e.getModifierState() properties
• New normalized onBeforeInput event
• React.Children.count has been added as a helper for counting the number of children

• Re-renders are batched in more cases
• Events: e.view properly normalized
• Added Support for more HTML attributes (coords, crossOrigin, download, hrefLang, mediaGroup, muted, scrolling, shape, srcSet, start, useMap)
• Improved SVG support
  • Changing className on a mounted SVG component now works correctly
  • Added support for elements mask and tspan
  • Added support for attributes dx, dy, fillOpacity, fontFamily, fontSize, markerEnd, markerMid, markerStart, opacity, patternContentUnits, patternUnits, preserveAspectRatio, strokeDasharray, strokeOpacity
• CSS property names with vendor prefixes (Webkit, ms, Moz, O) are now handled properly
• Duplicate keys no longer cause a hard error; now a warning is logged (and only one of the children with the same key is shown)
• img event listeners are now unbound properly, preventing the error "Two valid but unequal nodes with the same data-reactid"
• Added explicit warning when missing polyfills

• PureRenderMixin: a mixin which helps optimize "pure" components
• Perf: a new set of tools to help with performance analysis
• Update: New $apply command to transform values
• TransitionGroup bug fixes with null elements, Android

• Now includes the pre-built packages under dist/.
• envify is properly listed as a dependency instead of a peer dependency

• Added support for namespaces, eg <Components.Checkbox />
• JSXTransformer
  • Enable the same harmony features available in the command line with <script type="text/jsx;harmony=true">
  • Scripts are downloaded in parallel for more speed. They are still executed in order (as you would expect with normal script tags)
  • Fixed a bug preventing sourcemaps from working in Firefox

• Improved readme with usage and API information
• Improved ES6 transforms available with --harmony option
• Added --source-map-inline option to the jsx executable
• New transformWithDetails API which gives access to the raw sourcemap data

• Added warnings to help migrate towards descriptors
• Made it possible to server render without React-related markup (data-reactid, data-react-checksum). This DOM will not be mountable by React. Read the docs for React.renderComponentToStaticMarkup
• Added support for more attributes:
  • srcSet for <img> to specify images at different pixel ratios
  • textAnchor for SVG

• Ensure all void elements don’t insert a closing tag into the markup.
• Ensure className={false} behaves consistently
• Ensure this.refs is defined, even if no refs are specified.

• update function to deal with immutable data. Read the docs

• Added an option argument to transform function. The only option supported is harmony, which behaves the same as jsx --harmony on the command line. This uses the ES6 transforms from jstransform.

• The lifecycle methods componentDidMount and componentDidUpdate no longer receive the root node as a parameter; use this.getDOMNode() instead
• Whenever a prop is equal to undefined, the default value returned by getDefaultProps will now be used instead
• React.unmountAndReleaseReactRootNode was previously deprecated and has now been removed
• React.renderComponentToString is now synchronous and returns the generated HTML string
• Full-page rendering (that is, rendering the <html> tag using React) is now supported only when starting with server-rendered markup
• On mouse wheel events, deltaY is no longer negated
• When prop types validation fails, a warning is logged instead of an error thrown (with the production build of React, type checks are now skipped for performance)
• On input, select, and textarea elements, .getValue() is no longer supported; use .getDOMNode().value instead
• this.context on components is now reserved for internal use by React

• React now never rethrows errors, so stack traces are more accurate and Chrome's purple break-on-error stop sign now works properly
• Added support for SVG tags defs, linearGradient, polygon, radialGradient, stop
• Added support for more attributes:
  • crossOrigin for CORS requests
  • download and hrefLang for <a> tags
  • mediaGroup and muted for <audio> and <video> tags
  • noValidate and formNoValidate for forms
  • property for Open Graph <meta> tags
  • sandbox, seamless, and srcDoc for <iframe> tags
  • scope for screen readers
  • span for <colgroup> tags
• Added support for defining propTypes in mixins
• Added any, arrayOf, component, oneOfType, renderable, shape to React.PropTypes
• Added support for statics on component spec for static component methods
• On all events, .currentTarget is now properly set
• On keyboard events, .key is now polyfilled in all browsers for special (non-printable) keys
• On clipboard events, .clipboardData is now polyfilled in IE
• On drag events, .dragTransfer is now present
• Added support for onMouseOver and onMouseOut in addition to the existing onMouseEnter and onMouseLeave events
• Added support for onLoad and onError on <img> elements
• Added support for onReset on <form> elements
• The autoFocus attribute is now polyfilled consistently on input, select, and textarea

• React no longer adds an __owner__ property to each component's props object; passed-in props are now never mutated
• When nesting top-level components (e.g., calling React.renderComponent within componentDidMount), events now properly bubble to the parent component
• Fixed a case where nesting top-level components would throw an error when updating
• Passing an invalid or misspelled propTypes type now throws an error
• On mouse enter/leave events, .target, .relatedTarget, and .type are now set properly
• On composition events, .data is now properly normalized in IE9 and IE10
• CSS property values no longer have px appended for the unitless properties columnCount, flex, flexGrow, flexShrink, lineClamp, order, widows
• Fixed a memory leak when unmounting children with a componentWillUnmount handler
• Fixed a memory leak when renderComponentToString would store event handlers
• Fixed an error that could be thrown when removing form elements during a click handler
• Boolean attributes such as disabled are rendered without a value (previously disabled="true", now simply disabled)
• key values containing . are now supported
• Shortened data-reactid values for performance
• Components now always remount when the key property changes
• Event handlers are attached to document only when necessary, improving performance in some cases
• Events no longer use .returnValue in modern browsers, eliminating a warning in Chrome
• scrollLeft and scrollTop are no longer accessed on document.body, eliminating a warning in Chrome
• General performance fixes, memory optimizations, improvements to warnings and error messages

• React.addons.TestUtils was added to help write unit tests
• React.addons.TransitionGroup was renamed to React.addons.CSSTransitionGroup
• React.addons.TransitionGroup was added as a more general animation wrapper
• React.addons.cloneWithProps was added for cloning components and modifying their props
• Bug fix for adding back nodes during an exit transition for CSSTransitionGroup
• Bug fix for changing transitionLeave in CSSTransitionGroup
• Performance optimizations for CSSTransitionGroup
• On checkbox <input> elements, checkedLink is now supported for two-way binding

• Whitespace normalization has changed; now space between two tags on the same line will be preserved, while newlines between two tags will be removed
• The react-tools npm package no longer includes the React core libraries; use the react package instead.
• displayName is now added in more cases, improving error messages and names in the React Dev Tools
• Fixed an issue where an invalid token error was thrown after a JSX closing tag
• JSXTransformer now uses source maps automatically in modern browsers
• JSXTransformer error messages now include the filename and problematic line contents when a file fails to parse

• Added support for more attributes:
  • rows & cols for <textarea>
  • defer & async for <script>
  • loop for <audio> & <video>
  • autoCorrect for form fields (a non-standard attribute only supported by mobile WebKit)
• Improved error messages
• Fixed Selection events in IE11
• Added onContextMenu events

• Fixed bugs with TransitionGroup when children were undefined
• Added support for onTransition

• Upgraded jstransform and esprima-fb

• Added support for use in IE8
• Upgraded browserify, which reduced file size by ~65KB (16KB gzipped)

• Fixed a potential XSS vulnerability when using user content as a key: CVE-2013-7035

• Fixed bug with <input type="range"> and selection events.
• Fixed bug with selection and focus.
• Made it possible to unmount components from the document root.
• Fixed bug for disabled attribute handling on non-<input> elements.

• Fixed bug with transition and animation event detection.

• Memory usage improvements - reduced allocations in core which will help with GC pauses
• Performance improvements - in addition to speeding things up, we made some tweaks to stay out of slow path code in V8 and Nitro.
• Standardized prop -> DOM attribute process. This previously resulting in additional type checking and overhead as well as confusing cases for users. Now we will always convert your value to a string before inserting it into the DOM.
• Support for Selection events.
• Support for Composition events.
• Support for additional DOM properties (charSet, content, form, httpEquiv, rowSpan, autoCapitalize).
• Support for additional SVG properties (rx, ry).
• Support for using getInitialState and getDefaultProps in mixins.
• Support mounting into iframes.
• Bug fixes for controlled form components.
• Bug fixes for SVG element creation.
• Added React.version.
• Added React.isValidClass - Used to determine if a value is a valid component constructor.
• Removed React.autoBind - This was deprecated in v0.4 and now properly removed.
• Renamed React.unmountAndReleaseReactRootNode to React.unmountComponentAtNode.
• Began laying down work for refined performance analysis.
• Better support for server-side rendering - react-page has helped improve the stability for server-side rendering.
• Made it possible to use React in environments enforcing a strict Content Security Policy. This also makes it possible to use React to build Chrome extensions.

• Introduced a separate build with several "addons" which we think can help improve the React experience. We plan to deprecate this in the long-term, instead shipping each as standalone pieces. Read more in the docs.

• No longer transform class to className as part of the transform! This is a breaking change - if you were using class, you must change this to className or your components will be visually broken.
• Added warnings to the in-browser transformer to make it clear it is not intended for production use.
• Improved compatibility for Windows
• Improved support for maintaining line numbers when transforming.

• setState callbacks are now executed in the scope of your component.
• click events now work on Mobile Safari.
• Prevent a potential error in event handling if Object.prototype is extended.
• Don't set DOM attributes to the string "undefined" on update when previously defined.
• Improved support for <iframe> attributes.
• Added checksums to detect and correct cases where server-side rendering markup mismatches what React expects client-side.

• Improved environment detection so it can be run in a non-browser environment.

• Switch from using id attribute to data-reactid to track DOM nodes. This allows you to integrate with other JS and CSS libraries more easily.
• Support for more DOM elements and attributes (e.g., <canvas>)
• Improved server-side rendering APIs. React.renderComponentToString(<component>, callback) allows you to use React on the server and generate markup which can be sent down to the browser.
• prop improvements: validation and default values. Read our blog post for details...
• Support for the key prop, which allows for finer control over reconciliation. Read the docs for details...
• Removed React.autoBind. Read our blog post for details...
• Improvements to forms. We've written wrappers around <input>, <textarea>, <option>, and <select> in order to standardize many inconsistencies in browser implementations. This includes support for defaultValue, and improved implementation of the onChange event, and circuit completion. Read the docs for details...
• We've implemented an improved synthetic event system that conforms to the W3C spec.
• Updates to your component are batched now, which may result in a significantly faster re-render of components. this.setState now takes an optional callback as it's second parameter. If you were using onClick={this.setState.bind(this, state)} previously, you'll want to make sure you add a third parameter so that the event is not treated as the callback.

• Support for comment nodes <div>{/* this is a comment and won't be rendered */}</div>
• Children are now transformed directly into arguments instead of being wrapped in an array E.g. <div><Component1/><Component2/></div> is transformed into React.DOM.div(null, Component1(null), Component2(null)). Previously this would be transformed into React.DOM.div(null, [Component1(null), Component2(null)]). If you were using React without JSX previously, your code should still work.

• Fixed a number of bugs when transforming directories
• No longer re-write require()s to be relative unless specified

• Allow reusing the same DOM node to render different components. e.g. React.renderComponent(<div/>, domNode); React.renderComponent(<span/>, domNode); will work now.

• Improved the in-browser transformer so that transformed scripts will execute in the expected scope. The allows components to be defined and used from separate files.

• Upgrade Commoner so require statements are no longer relativized when passing through the transformer. This was a feature needed when building React, but doesn't translate well for other consumers of bin/jsx.
• Upgraded our dependencies on Commoner and Recast so they use a different directory for their cache.
• Freeze our Esprima dependency.

• Improved compatibility with other coding styles (specifically, multiple assignments with a single var).

• Switch from using the browserified build to shipping individual modules. This allows react-tools to be used with browserify.

• Fix bug in packaging resulting in broken module.

• Initial public release