49 lines
1.4 KiB
HTML
49 lines
1.4 KiB
HTML
<!--
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* @Author: chenxuan
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* @Date: 2021-12-26 16:30:03
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* @LastEditTime: 2022-08-13 01:46:42
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* @LastEditors: chenxuan
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-->
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<!DOCTYPE html>
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<html>
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<head>
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<meta charset="utf-8">
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<meta name="viewport" content="width=device-width, initial-scale=1">
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<title>state</title>
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</head>
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<body>
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<div id="app"></div>
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<script src="../package/old/react.development.js"></script>
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<script src="../package/old/react-dom.development.js"></script>
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<script src="../package/old/babel.min.js"></script>
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<script type="text/babel">
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class Weather extends React.Component{
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constructor(props){
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super(props)
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this.state={
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ishot:true
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}
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}
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render(){
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const {ishot}=this.state;
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// 解决this指向问题
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// this.demo 这是赋值操作，此时函数并没有调用
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// 点击的时候调用 demo函数 此时是直接调用，由于类的局部默认开启严格模式，this指向 undefined
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// 通过 bind() 传入this 修改this指向 将this指向Weather实例
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return <h1 onClick={this.demo.bind(this)}>今天天气很{ishot ? '炎热' : '凉爽'}</h1>
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}
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// demo定义在 Weather的原型上，供实例使用
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// 通过Weather的实例调用时 this指向实例
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demo(){
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this.setState({
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ishot:!this.state.ishot
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})
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}
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}
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ReactDOM.render(
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<Weather/>,document.getElementById('app')
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)
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</script>
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</body>
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</html> |