What's new in React 19
summary
React 19 stabilizes concrete APIs: transitions now accept async functions (but post-await updates need an extra startTransition until async context lands), and multiple concurrent transitions batch into a single commit so later updates win. New hooks and APIs include useActionState (actions auto-receive formData and expose pending + result), useFormStatus and useOptimistic for optimistic updates, plus server improvements: async React Server Components with Suspense streaming, use API to pass promises to client, plus server actions, ref-as-prop, head/CSS hoisting and browser-hint APIs.
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chapters (10)
- 0:00Introduction
- 0:21Transitions with async actions
- 3:54useActionState hook demo
- 6:42Form actions and status
- 8:07useOptimistic hook explained
- 10:30React Server Components
- 13:17Client components and use
- 15:41Server actions overview
- 16:44Other React 19 improvements
- 18:29Browser hints and metadata
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