react--ref操作虛擬Dom

React的ref有3種用法：

1. 字符串(已廢棄)
2. 回調函數
3. React.createRef()

老規矩先上代碼

新增pages/Ref.js文件

import React from 'react'; export default class Ref extends React.Component{ constructor(props){ super(props); this.ref3 = React.createRef(); } componentDidMount(){ console.log(this.refs.input); console.log(this.ref2); console.log(this.ref3); this.refs.input.value = 'ref1'; this.ref2.value = 'ref2'; this.ref3.current.value = 'ref3'; } render(){ return ( <div> {/*ref1*/} <input ref="input" />
 {/*ref2*/} <input ref={(input) => {this.ref2 = input}} />
 {/*ref3*/} <input ref={this.ref3} />
      </div>
 ) } }

route/index.js修改如下

import React from 'react'; import {Switch, Route} from "react-router-dom"; import asyncComponent from '../lazy'; import Home2 from '../pages/Home2'; import OnePage from '../pages/OnePage'; import TwoPage from '../pages/TwoPage'; import This from '../pages/This'; import Mount from '../pages/Mount'; import HooksTest1 from '../hooks/test1'; import AxiosTest from '../pages/AxiosTest'; import Refs from '../pages/Ref'; //import HooksUseState from '../hooks/useState';
const HooksUseState = asyncComponent(() => import ('../hooks/useState')); const Routers = ( <Switch>
        <Route path="/" exact component={Home2} />
        <Route path="/onePage" component={OnePage} />
        <Route path="/twoPage/:id" component={TwoPage} />
        <Route path="/this" component={This} />
        <Route path="/mount"  component={Mount} />
        <Route path="/hooksTest1" component={HooksTest1} />
        <Route path="/axiosTest" component={AxiosTest} />
        <Route path="/refs" component={Refs} />
        <Route path="/hooksUseState" component={HooksUseState} />
    </Switch>
); export default Routers

啟動項目npm start，打開http://localhost:3000/#/refs

查看控制台打印的結果 我代碼里有注釋1、2、3，打印也有1、2、3應該很清楚吧

現在大部分都用第三種，因為你點開第三種的小箭頭會顯示很多屬性，隨便用 大部分都是你認識的Dom屬性、事件和方法