React 19

React 19 is a major release that introduces server-first architecture, new hooks, and automatic optimizations. Here is the quick-reference checklist of what shi

Render data-only components on the server to ship less JavaScript and fetch data closer to the source.

Run server-side mutations -- database writes, uploads, emails -- directly from components without building API routes.

Handle form submissions with the action prop, replacing manual onSubmit, preventDefault, and state wiring.

Read promises and conditionally read context with the use hook, even inside branches and loops.

Update the UI instantly while a mutation is in flight, then reconcile with the server result.

Pass ref as a regular prop in function components, replacing forwardRef entirely.

Set the page title, description, and other head tags directly from components without react-helmet.

Preload stylesheets, scripts, fonts, and other resources before React renders to speed up initial load and navigation.

Automatically optimize re-renders with the React Compiler, replacing most manual useMemo, useCallback, and React.memo.

A condensed summary of the 25 most important best practices drawn from every page in this section.