React-19

The use() API

Read promises and context conditionally with React 19's new use() function

Form Actions & useActionState

Wire forms to functions and track pending, error, and success state with zero boilerplate

useOptimistic

Show instant UI updates before the server confirms — then reconcile automatically

useTransition & useDeferredValue

Keep the UI responsive during heavy updates by marking work as non-urgent

ref as a Prop & Cleanup

Pass refs like any other prop and run cleanup when a ref detaches — no more forwardRef