react-patterns

Server Components and Client Components in React 19 are combined by fetching data on the server and passing it to small Client Components for interactivity. This architecture ensures robust apps by correctly managing server/client boundaries and data flow.

Form submissions with Server Actions in React 19 are handled using 'use server' directives alongside useFormState and useFormStatus hooks. This pattern validates input, handles mutations, and revalidates caches for secure and efficient data updates.

useOptimistic in React works by immediately showing the expected state before the server mutation completes. It provides smooth UX during asynchronous Server Actions by reverting to the actual state once the server response is received.

Manual memoization is unnecessary when using the React Compiler, as it automatically optimizes expensive computations and prevents unnecessary re-renders. Developers can avoid premature memoization and rely on the compiler for performance optimizations.

TypeScript is fully supported with React 19 Server Components and Actions. Type-safe component patterns and generic components ensure end-to-end type safety across server/client boundaries, form handling, and Suspense flows.

Migrating a Next.js codebase to React 19 involves converting data fetching to Server Components, introducing Server Actions for mutations, and applying optimistic UI. A migration checklist ensures correct Suspense and concurrent feature implementation.