name: react-19 description: React 19.3+ patterns. Use for forms, async data, pre-rendering, transitions, refs, context, metadata.

React 19.3+

useState + onChange for forms → useActionState → examples/form-action.tsx
await in server components → pass promise, use() in client → examples/use-server-promise.tsx
forwardRef → ref as prop
useCallback / useMemo → compiler handles it
useContext → use(Context)
Context.Provider → <Context value={}>
Manual state reset on prop change → key prop

Forms: useActionState(fn, init) + useOptimistic + useFormStatus → examples/form-action.tsx
Pre-rendering: <Activity mode="hidden"> → examples/activity-prerender.tsx
Effect events: useEffectEvent() for non-reactive logic in effects → examples/effect-event.tsx
Async data: pass promise from server, unwrap with use() → examples/use-server-promise.tsx
ViewTransition: wrap elements, use startTransition() + addTransitionType() → examples/view-transition.tsx
Mutations outside forms: useTransition + Server Action → examples/server-action-mutation.tsx
Suspense: <Suspense fallback={...}> wraps async components
Deferred value: useDeferredValue(value, initialValue)
Request memoization: cache(async fn) with cacheSignal()
Server Action: "use server" + revalidatePath() / revalidateTag()
Metadata: <title>, <meta>, <link> hoisted to <head>
Refs: ref as prop, cleanup via return function