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React
v19.2
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    react@19.2

  • Overview
  • Hooks
    • useActionState
    • useCallback
    • useContext
    • useDebugValue
    • useDeferredValue
    • useEffect
    • useEffectEvent
    • useId
    • useImperativeHandle
    • useInsertionEffect
    • useLayoutEffect
    • useMemo
    • useOptimistic
    • useReducer
    • useRef
    • useState
    • useSyncExternalStore
    • useTransition
  • Components
    • <Fragment> (<>)
    • <Profiler>
    • <StrictMode>
    • <Suspense>
    • <Activity>
    • <ViewTransition> - This feature is available in the latest Canary version of React
  • APIs
    • act
    • addTransitionType - This feature is available in the latest Canary version of React
    • cache
    • cacheSignal
    • captureOwnerStack
    • createContext
    • lazy
    • memo
    • startTransition
    • use
    • experimental_taintObjectReference - This feature is available in the latest Experimental version of React
    • experimental_taintUniqueValue - This feature is available in the latest Experimental version of React

  • react-dom@19.2

  • Hooks
    • useFormStatus
  • Components
    • Common (e.g. <div>)
    • <form>
    • <input>
    • <option>
    • <progress>
    • <select>
    • <textarea>
    • <link>
    • <meta>
    • <script>
    • <style>
    • <title>
  • APIs
    • createPortal
    • flushSync
    • preconnect
    • prefetchDNS
    • preinit
    • preinitModule
    • preload
    • preloadModule
  • Client APIs
    • createRoot
    • hydrateRoot
  • Server APIs
    • renderToPipeableStream
    • renderToReadableStream
    • renderToStaticMarkup
    • renderToString
    • resume
    • resumeToPipeableStream
  • Static APIs
    • prerender
    • prerenderToNodeStream
    • resumeAndPrerender
    • resumeAndPrerenderToNodeStream

  • React Compiler

  • Configuration
    • compilationMode
    • gating
    • logger
    • panicThreshold
    • target
  • Directives
    • "use memo"
    • "use no memo"
  • Compiling Libraries

  • React DevTools

  • React Performance tracks

  • eslint-plugin-react-hooks

  • Lints
    • exhaustive-deps
    • rules-of-hooks
    • component-hook-factories - This feature is available in the latest RC version
    • config - This feature is available in the latest RC version
    • error-boundaries - This feature is available in the latest RC version
    • gating - This feature is available in the latest RC version
    • globals - This feature is available in the latest RC version
    • immutability - This feature is available in the latest RC version
    • incompatible-library - This feature is available in the latest RC version
    • preserve-manual-memoization - This feature is available in the latest RC version
    • purity - This feature is available in the latest RC version
    • refs - This feature is available in the latest RC version
    • set-state-in-effect - This feature is available in the latest RC version
    • set-state-in-render - This feature is available in the latest RC version
    • static-components - This feature is available in the latest RC version
    • unsupported-syntax - This feature is available in the latest RC version
    • use-memo - This feature is available in the latest RC version

  • Rules of React

  • Overview
    • Components and Hooks must be pure
    • React calls Components and Hooks
    • Rules of Hooks

  • React Server Components

  • Server Components
  • Server Functions
  • Directives
    • 'use client'
    • 'use server'

  • Legacy APIs

  • Legacy React APIs
    • Children
    • cloneElement
    • Component
    • createElement
    • createRef
    • forwardRef
    • isValidElement
    • PureComponent

Is this page useful?

On this page

  • Overview
  • Reference
  • useMemo(calculateValue, dependencies)
  • Usage
  • Skipping expensive recalculations
  • Skipping re-rendering of components
  • Preventing an Effect from firing too often
  • Memoizing a dependency of another Hook
  • Memoizing a function
  • Troubleshooting
  • My calculation runs twice on every re-render
  • My useMemo call is supposed to return an object, but returns undefined
  • Every time my component renders, the calculation in useMemo re-runs
  • I need to call useMemo for each list item in a loop, but it’s not allowed