【React】建立React 環境

引入js

<script crossorigin src="https://unpkg.com/react@18/umd/react.development.js"></script>
<script crossorigin src="https://unpkg.com/react-dom@18/umd/react-dom.development.js"></script>
<script src="https://unpkg.com/babel-standalone@6/babel.min.js"></script>

建立根物件

<div id="root"></div>

渲染Dom物件

<script type="text/babel">
  function App(){
    return <h1>Hello React</h1>
  }

  const el = document.getElementById("root");
  const root = ReactDOM.createRoot(el);
  root.render(<App />);
 /* 簡易寫法
  ReactDOM
     .createRoot(el)
     .render(<App />);
  */
</script>