React Strict Mode

Strict Mode helps find problems in development.

Usage

```javascript import { StrictMode } from 'react';

function App() { return ( <StrictMode> <MyComponent /> </StrictMode> ); } ```

What It Does

- Warns about deprecated APIs - Detects unsafe lifecycles - Warns about legacy string refs - Detects unexpected side effects - Ensures reusable state

Double Rendering

In development, renders components twice to catch bugs:

```javascript useEffect(() => { console.log('Effect runs'); // Runs twice in StrictMode }, []); ```

Remember

- Only in development - No visual output - Helps catch bugs early - Applies to children only

> Next: Learn code splitting strategies!