react元件基本用法示例小結
阿新 • • 發佈:2020-04-28
本文例項講述了react元件基本用法。分享給大家供大家參考,具體如下:
元件間傳值:
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>test</title> </head> <body> <div id="app"> </div> <script src="../js/react.production.min.js"></script><!--react核心庫--> <script src="../js/react-dom.production.min.js"></script><!--操作DOM的react擴充套件庫--> <script src="../js/babel.min.js"></script><!--解析JSX語法--> <script type="text/babel"> class Com extends React.Component { click = ()=>{ // console.log(this.input); // console.log(this.p.innerText); console.log(this.refs.my.value);//父元件訪問子元件用refs }; render() { return ( <div> <input type="text" ref={(input)=>{this.input=input}}/> <p ref={(p)=>{this.p=p}}>我是段落</p> <input type="text" ref="my"/> <button onClick={this.click}>點選</button> </div> ); } } ReactDOM.render(<Com/>,document.getElementById('app')); </script> </body> </html>
列表:
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>test</title> </head> <body> <div id="app"></div> <script src="../js/react.production.min.js"></script><!--react核心庫--> <script src="../js/react-dom.production.min.js"></script><!--操作DOM的react擴充套件庫--> <script src="../js/babel.min.js"></script><!--解析JSX語法--> <script type="text/babel"> class Add extends React.Component { click = ()=>{ this.props.allAdd(this.input.value); }; render() { const {length} = this.props; return ( <div> <input type="text" ref={(input)=>{this.input=input}}/> <button onClick={this.click}>add{length}</button> </div> ) } } class List extends React.Component { render() { const {list} = this.props; return ( <div> <ul> { list.map((v,i)=>{ return <li key={i}>{v}</li> }) } </ul> </div> ) } } class App extends React.Component { state = { list:['吃飯','睡覺','打遊戲','游泳'] }; add = (value)=>{ const {list} = this.state;//獲取原先的list list.unshift(value);//將新增的值傳入list this.setState(list);//重新設定list }; render() { const {list} = this.state;//獲取list return ( <div> <Add allAdd={this.add} length={list.length}/> <List list={list} /> </div> ) } } ReactDOM.render(<App />,document.getElementById('app')); </script> </body> </html>
受控元件和非受控元件:
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>test</title> </head> <body> <div id="app"></div> <script src="../js/react.production.min.js"></script><!--react核心庫--> <script src="../js/react-dom.production.min.js"></script><!--操作DOM的react擴充套件庫--> <script src="../js/babel.min.js"></script><!--解析JSX語法--> <script type="text/babel"> class Com extends React.Component { state = { age:'' }; //非受控元件 不受state控制 click = () => { console.log(this.input.value); }; change = (event)=>{ console.log(event.target.value); this.setState({ age: event.target.value }) }; render() { const {age} = this.props; return ( <div> 姓名:<input type="text" ref={(input)=>{this.input=input}}/> <button onClick={this.click}>獲取姓名</button> 年齡:<input type="text" value={age} onChange={this.change}/> </div> ); }; } ReactDOM.render(<Com />,document.getElementById('app')); </script> </body> </html>
元件生命週期:
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>Test</title> </head> <body> <div id="app"></div> <script src="../js/react.production.min.js"></script><!--react核心庫--> <script src="../js/react-dom.production.min.js"></script><!--操作DOM的react擴充套件庫--> <script src="../js/babel.min.js"></script><!--解析JSX語法--> <script type="text/babel"> class Com extends React.Component { state = { msg:123 }; sing() { return new Promise((resolve,reject)=>{ setTimeout(()=>{ resolve('唱一首歌'); },1000); }) }; async get() { await this.sing().then((res)=>{ console.log(res); }); }; componentWillMount() { //will會先執行,但不一定先執行完畢 console.log('之前'); // this.get(); } componentDidMount() { //進行ajax操作,獲取後臺資料 console.log('之後'); } shouldComponentUpdate(nextProps,nextState) { const {msg} = this.state; //如果沒有 if ({msg} !== nextState) { return true; } console.log('更新'); return false; } componentWillUpdate() { console.log('更新之前'); } componentDidUpdate() { console.log('更新之後'); //再次獲取資料 } click = ()=>{ this.setState({ msg: 234 }) }; render() { console.log('render'); const {msg} = this.state; return( <div> <h1>{msg}</h1> <button onClick={this.click}>更新</button> </div> ) } } ReactDOM.render(<Com />,document.getElementById('app')); </script> </body> </html>
希望本文所述對大家react程式設計有所幫助。