React 18 以下支援

ReactDOM.render is no longer supported in React 18

Eeact 18 以下版本，index.js

import React from 'react';
import ReactDOM from 'react-dom';
import './index.css';
import App from './App';
import reportWebVitals from './reportWebVitals';ReactDOM.render(
  <React.StrictMode>
    <App />
  </React.StrictMode>,
  document.getElementById('root')
);

// If you want to start measuring performance in your app, pass a function
// to log results (for example: reportWebVitals(console.log))
// or send to an analytics endpoint. Learn more: https://bit.ly/CRA-vitals
reportWebVitals();


修改為以下

import React from 'react';
import ReactDOM from 'react-dom/client';
import './index.css';
import App from './App';


const root = ReactDOM.createRoot(document.getElementById("root"));
root.render(<App />);