Technology·Feb 27, 2026·15 min read
useActionState deep dive: mutation flows, optimistic UI, queued actions, and when a data layer still wins (React 19+)
A practical deep dive into React 19’s useActionState: how the Action queue works, why Transitions matter for isPending, progressive enhancement with permalink, integrating useOptimistic for instant UX, cancellation with AbortController, and a decision framework for when TanStack Query / SWR / RTK Query should still own caching, retries, and invalidation.
