react-dev

Type-safe React 18–19 patterns with compile-time guarantees for components, hooks, events, and routing. Type-safe React = compile-time guarantees = confident refactoring. NOT for: non-React TypeScript, vanilla JS React React 19 breaking changes require migration. Key patterns: ref as prop - forwardRef deprecated: useActionState - replaces useFormState: use() - unwraps promises/context: See react-19-patterns.md for useOptimistic, useTransition, migration checklist. Props - extend native elements: Children typing : Discriminated unions for variant props: Use specific event types for accurate target typing: See event-handlers.md for focus, drag, clipboard, touch, wheel events. useState - explicit for unions/null: useRef - null for DOM, value for mutable: useReducer - discriminated unions for actions: Custom hooks - tuple returns with as const: useContext - null guard pattern: See hooks.md for useCallback, useMemo, useImperativeHandle, useSyncExternalStore. Generic components infer types from props - no manual annotations at call site. Pattern - keyof T for column keys, render props for custom rendering: Constrained generics for required properties: See generic-components.md for Select, List, Modal, FormField patterns. React 19 Server Components run on server, can be async.