React 19 Compiler is Here! You can test it now.

React 19 introduces a groundbreaking experimental feature: the React Compiler. This new tool aims to automatically optimize your React applications at build time, making your code faster and more efficient.

What is the React Compiler?

The React Compiler is an innovative tool designed to enhance your React application by applying optimizations automatically. It operates at build time and understands JavaScript semantics and the Rules of React, which allows it to optimize your code without requiring any manual changes.

Key Features of the React Compiler:

• Automatic Memoization: The compiler can automatically memoize your components, eliminating the need for manual use of useMemo, useCallback, and React.memo.
• ESLint Plugin: The compiler comes with an ESLint plugin that provides real-time feedback in your code editor, helping you improve code quality even if you’re not using the compiler itself.

React 19 Beta: The React Compiler requires React 19 Beta to function properly.

Should You Try the React Compiler?

The React Compiler is still in an experimental phase, meaning it has some rough edges and is not fully ready for production use. However, it has been tested in production environments at companies like Meta. If you want to experiment with it, start by applying it to a small part of your project. This will allow you to provide valuable feedback while minimizing potential risks.

Getting Started with the React Compiler

Installation

To begin using the React Compiler, follow these steps:

Check Compatibility: This script checks how many components can be optimized, the usage of StrictMode, and any incompatible libraries.

npx react-compiler-healthcheck

Install ESLint Plugin: Add the plugin to your ESLint configuration:

npm install eslint-plugin-react-compiler

module.exports = {
  plugins: ['eslint-plugin-react-compiler'],
  rules: {
    'react-compiler/react-compiler': 2,
  },
};

Use with Babel: Add the plugin to your Babel configuration:

npm install babel-plugin-react-compiler

// babel.config.js
const ReactCompilerConfig = { /* ... */ };

module.exports = function () {
  return {
    plugins: [
      ['babel-plugin-react-compiler', ReactCompilerConfig], // must run first!
      // ...
    ],
  };
};

Integrations with Other Tools

Vite:

// vite.config.js
const ReactCompilerConfig = { /* ... */ };

export default defineConfig(() => {
  return {
    plugins: [
      react({
        babel: {
          plugins: [
            ["babel-plugin-react-compiler", ReactCompilerConfig],
          ],
        },
      }),
    ],
  };
});

Next.js: Configure Babel by adding a babel.config.js file.

Conclusion

React 19’s introduction of the experimental React Compiler is a significant step towards more efficient and optimized React applications. While it’s not yet ready for full production use, experimenting with it in smaller projects can provide valuable insights and feedback. Stay tuned for more updates as the React Compiler continues to evolve and improve.