React_使用es5和es6语法渲染和添加class

React入门

//react的核心库
<script src="https://cdn.jsdelivr.net/npm/react@17/umd/react.development.js"></script>
//react操作dom的核心库，类似于jquery
<script src="https://cdn.jsdelivr.net/npm/react-dom@17/umd/react-dom.development.js"></script>
//用来解析es6语法
<script src="https://unpkg.com/babel-standalone@6/babel.min.js"></script>

es5 写法

基础语法

必须要有根元素进行包裹

//创建元素

var element = React.createElement('li',{},'hello') //节点，节点属性，标签内容

//var element = React.createElement('li',null,'hello')

//渲染元素

ReactDOM.render(element,document.getElementById('root1'))

//床架年组建，使用extends继承

React.component

<!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><!-- react渲染三步走1.定义一个容器用于存放虚拟dom2.创建虚拟dom元素3.把虚拟dom元素渲染到页面上--><div id="root1"></div>
</body>
<script src="https://cdn.jsdelivr.net/npm/react@17/umd/react.development.js"></script>
<script src="https://cdn.jsdelivr.net/npm/react-dom@17/umd/react-dom.development.js"></script>
<script src="https://unpkg.com/babel-standalone@6/babel.min.js"></script>
<script>//es5方法创建//创建元素var element = React.createElement('li',{},'hello')//渲染元素ReactDOM.render(element,document.getElementById('root1'))
//
</script>
</html>

多层嵌套的关系

注意如果在react中添加类名不能写class要写className，同时不能再同一个容器里渲染多个虚拟dom，必须要有根元素进行包裹

//如果有多层嵌套的关系

var li1 = React.createElement('li',null,'11111')

var li2 = React.createElement('li',{class:'list-li'},'22222')

var _ul = React.createElement('ul',{id:'list'},li1,li2)

ReactDOM.render(_ul,document.getElementById('root2'))

es6写法

注意在使用es6语法时候script必须表明type为text/balel

<!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="root1"></div><script type="text/babel">//es6方法创建,ReactDOM.render(<ul><li className='lili'>111</li><li>222</li></ul> ,document.getElementById('root1'))</script><div id="root2"></div><script type="text/babel">//es6方法创建,jsx简单写法let root2=document.getElementById('root2')let div= <div className='hello'><h1>hello react</h1></div>ReactDOM.render(div,root2)</script>
</body>
<script src="https://cdn.jsdelivr.net/npm/react@17/umd/react.development.js"></script>
<script src="https://cdn.jsdelivr.net/npm/react-dom@17/umd/react-dom.development.js"></script>
<!-- 用于解析babel -->
<script src="https://unpkg.com/babel-standalone@6/babel.min.js"></script>
</html>