1, StrictMode
After creating the project through the create-react-app scaffolding, the project’s index.js code looks like this:
import React from 'react';
import ReactDOM from 'react-dom';
import './index.css';
import App from './App';
import * as serviceWorker from './serviceWorker';
ReactDOM.render(
<React.StrictMode>
<App />
</React.StrictMode>,
document.getElementById('root')
);
// If you want your app to work offline and load faster, you can change
// unregister() to register() below. Note this comes with some pitfalls.
// Learn more about service workers: https://bit.ly/CRA-PWA
serviceWorker.unregister();
Copy the code
StrictMode enables React StrictMode. This is different from what the application expects. About the introduction of strict mode can refer to the official document: zh-hans.reactjs.org/docs/strict…