React 19 introduces the React Compiler that auto-memoizes components, eliminating most manual useMemo/useCallback calls. The new use() hook replaces useEffect data‑fetching anti‑patterns, useActionState handles form submissions, and useFormStatus propagates pending states down the component tree. Understanding the mental model lets you write less code that does more.
Each stage in order — click any step to read what it does.
React 19 component lifecycle and hook execution order.
The trade-offs worth knowing before you build this.
The React Compiler handles memoization automatically. Audit your codebase and remove manual memos after enabling the compiler.
Wrap async data in a promise and pass it to use(). It suspends while loading, no effect cleanup needed.
Replaces the [loading, error, data] state + try/catch pattern for form submissions with a clean server action integration.
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