第一个包是react的库，用于组件，工具，UI渲染等

第二个包是react库是为了虚拟DOM最终挂载到真实DOM中

第三个包是用来解析reactDOM的语法，相当于编译器

<script src="<https://unpkg.com/react@17/umd/react.development.js>"></script>
<script src="<https://unpkg.com/react-dom@17/umd/react-dom.development.js>"></script>
<script src="<https://unpkg.com/babel-standalone@6/babel.min.js>"></script>

如何渲染

标签 id = “idName”

<script type="text/babel">
        let title = React.createElement('li', null, 'hellow react');

        ReactDOM.render(title, document.getElementById("ddd"))
</script>