规则
①定义虚拟dom，非字符串。类似html模板
②Mustache语法是{}
③class属性对应为className
④只有一个根标签
⑤须有babel.js库
⑥自定义组件标签大写，非自定义小写
⑦事件如onClick需转为小写，onclick
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>jsx语法规则</title>
<style>
.title{
background-color: orange;
width: 200px;
}
</style>
</head>
<body>
<!-- 准备好一个“容器” -->
<div id="app"></div>
<!-- 引入react核心库 -->
<script type="text/javascript" src="../js/react.development.js"></script>
<!-- 引入react-dom，用于支持react操作DOM -->
<script type="text/javascript" src="../js/react-dom.development.js"></script>
<!-- 引入babel，用于将jsx转为js -->
<script type="text/javascript" src="../js/babel.min.js"></script>
<script type="text/babel" >
const text = 'Hellow React'
//1.创建虚拟DOM
const VDOM = (
<div style={{width:'500px',height:'300px',backgroundColor:'black',margin:'0 auto'}}>
<h1 style={{color:'white',textAlign:'center' ,lineHeight:'300px'}}>{text}</h1>
</div>
)
//2.渲染虚拟DOM到页面
ReactDOM.render(VDOM,document.getElementById('app'))
</script>
