react-19

Manual memoization in React 19 is eliminated by enabling the React Compiler. The compiler automatically optimizes components, removing the need for useMemo and useCallback while improving performance and reducing boilerplate.

To configure the React Compiler in Next.js 15, you must explicitly enable it within your next.config.ts file. This allows your project to leverage compiler-based optimizations for server and client components.

React 19 does not require forwardRef for passing refs. The framework now treats refs as plain props, simplifying component interfaces and eliminating the need for forwardRef wrappers entirely.

The use() hook in React 19 reads promises or accesses context directly. It uniquely allows conditional context usage within components, streamlining asynchronous data fetching and state management logic.

Server components are the default component type in React 19 and Next.js 15. Client interactivity is opt-in, requiring explicit 'use client' directives to ensure safe client components.

You track form submission state in React 19 using the useActionState hook. It manages pending indicators and form submission state, simplifying asynchronous form handling without manual state variables.