v19.2.0

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Below is a list of all new features, APIs, and bug fixes.

Read the React 19.2 release post for more information.

New React Features

• <Activity>: A new API to hide and restore the UI and internal state of its children.
• useEffectEvent is a React Hook that lets you extract non-reactive logic into an Effect Event.
• cacheSignal (for RSCs) lets your know when the cache() lifetime is over.
• React Performance tracks appear on the Performance panel’s timeline in your browser developer tools

New React DOM Features

• Added resume APIs for partial pre-rendering with Web Streams:
  • resume: to resume a prerender to a stream.
  • resumeAndPrerender: to resume a prerender to HTML.
• Added resume APIs for partial pre-rendering with Node Streams:
  • resumeToPipeableStream: to resume a prerender to a stream.
  • resumeAndPrerenderToNodeStream: to resume a prerender to HTML.
• Updated prerender APIs to return a postponed state that can be passed to the resume APIs.

Notable changes

• React DOM now batches suspense boundary reveals, matching the behavior of client side rendering. This change is especially noticeable when animating the reveal of Suspense boundaries e.g. with the upcoming <ViewTransition> Component. React will batch as much reveals as possible before the first paint while trying to hit popular first-contentful paint metrics.
• Add Node Web Streams (prerender, renderToReadableStream) to server-side-rendering APIs for Node.js
• Use underscore instead of : IDs generated by useId

All Changes

React

• <Activity /> was developed over many years, starting before ClassComponent.setState (@​acdlite @​sebmarkbage and many others)
• Stringify context as "SomeContext" instead of "SomeContext.Provider" (@​kassens #​33507)
• Include stack of cause of React instrumentation errors with %o placeholder (@​eps1lon #​34198)
• Fix infinite useDeferredValue loop in popstate event (@​acdlite #​32821)
• Fix a bug when an initial value was passed to useDeferredValue (@​acdlite #​34376)
• Fix a crash when submitting forms with Client Actions (@​sebmarkbage #​33055)
• Hide/unhide the content of dehydrated suspense boundaries if they resuspend (@​sebmarkbage #​32900)
• Avoid stack overflow on wide trees during Hot Reload (@​sophiebits #​34145)
• Improve Owner and Component stacks in various places (@​sebmarkbage, @​eps1lon: #​33629, #​33724, #​32735, #​33723)
• Add cacheSignal (@​sebmarkbage #​33557)

React DOM

• Block on Suspensey Fonts during reveal of server-side-rendered content (@​sebmarkbage #​33342)
• Use underscore instead of : for IDs generated by useId (@​sebmarkbage, @​eps1lon: #​32001, #​33342#​33099, #​33422)
• Stop warning when ARIA 1.3 attributes are used (@​Abdul-Omira #​34264)
• Allow nonce to be used on hoistable styles (@​Andarist #​32461)
• Warn for using a React owned node as a Container if it also has text content (@​sebmarkbage #​32774)
• s/HTML/text for for error messages if text hydration mismatches (@​rickhanlonii #​32763)
• Fix a bug with React.use inside React.lazy-ed Component (@​hi-ogawa #​33941)
• Enable the progressiveChunkSize option for server-side-rendering APIs (@​sebmarkbage #​33027)
• Fix a bug with deeply nested Suspense inside Suspense fallback when server-side-rendering (@​gnoff #​33467)
• Avoid hanging when suspending after aborting while rendering (@​gnoff #​34192)
• Add Node Web Streams to server-side-rendering APIs for Node.js (@​sebmarkbage #​33475)

React Server Components

• Preload <img> and <link> using hints before they're rendered (@​sebmarkbage #​34604)
• Log error if production elements are rendered during development (@​eps1lon #​34189)
• Fix a bug when returning a Temporary reference (e.g. a Client Reference) from Server Functions (@​sebmarkbage #​34084, @​denk0403 #​33761)
• Pass line/column to filterStackFrame (@​eps1lon #​33707)
• Support Async Modules in Turbopack Server References (@​lubieowoce #​34531)
• Add support for .mjs file extension in Webpack (@​jennyscript #​33028)
• Fix a wrong missing key warning (@​unstubbable #​34350)
• Make console log resolve in predictable order (@​sebmarkbage #​33665)

React Reconciler

• createContainer and createHydrationContainer had their parameter order adjusted after on* handlers to account for upcoming experimental APIs