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StrictMode

Enables extra development checks for the wrapped component tree.

Since React 16.3 Spec ↗

Syntax

<StrictMode>...</StrictMode>

Returns

element — A wrapper that activates strict development-only behaviors.

Examples

import { StrictMode } from 'react';
import { createRoot } from 'react-dom/client';

createRoot(document.getElementById('root')).render(
  <StrictMode>
    <App />
  </StrictMode>
);

Notes

In development, StrictMode double-invokes component, initializer, and effect setup/cleanup functions to surface impure logic and missing cleanup, warns about deprecated APIs, and adds no behavior or overhead in production. It only affects the tree inside it and can wrap part of an app.

See also