01_Hello_React案例

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    
    <div id="root"></div>
    <div id="app"></div>

    <!-- 添加依赖 -->
    <!-- 依赖三个包 -->
    <!-- CDN引入 -->
    <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> 
    <!-- babel -->
    <script src="https://unpkg.com/babel-standalone@6/babel.min.js"></script>

<!-- 下载引入 -->

<!-- npm下载引入（脚手架） -->
<script type="text/babel">

    //编写React代码（jsx语法)
    //jsx语法 -> 普通的JavaScript代码 - > babel

    //渲染Hello world
    //React18之前：ReactDOM.render
    // ReactDOM.render(<h2>Hello World</h2>,document.querySelector("#root"));

    //React18之后
    const root = ReactDOM.createRoot(document.querySelector("#root"))
    root.render(<h2>Hello World</h2>)

    const app = ReactDOM.createRoot(document.querySelector("#app"))
    app.render(<h2>你好啊，李银河</h2>)


</script>
</body>
</html>