【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>