react组件基本用法示例小结

日期: 2020-06-22 17:48:53

本文实例讲述了react组件基本用法。分享给大家供大家参考，具体如下：

组件间传值：

<!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核心库-->
<script src="../js/react-dom.production.min.js"></script><!--操作DOM的react扩展库-->
<script src="../js/babel.min.js"></script><!--解析JSX语法-->
<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);//父组件访问子组件用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}>点击</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核心库-->
<script src="../js/react-dom.production.min.js"></script><!--操作DOM的react扩展库-->
<script src="../js/babel.min.js"></script><!--解析JSX语法-->
<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:['吃饭','睡觉','打游戏','游泳']
    };
    add = (value)=>{
      const {list} = this.state;//获取原先的list
      list.unshift(value);//将添加的值传入list
      this.setState(list);//重新设置list
    };
    render() {
      const {list} = this.state;//获取list
      return (
        <div>
          <Add allAdd={this.add} length={list.length}/>
          <List list={list} />
        </div>
      )
    }
  }
 
  ReactDOM.render(<App />,document.getElementById('app'));
</script>
</body>
</html>

受控组件和非受控组件：

<!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核心库-->
<script src="../js/react-dom.production.min.js"></script><!--操作DOM的react扩展库-->
<script src="../js/babel.min.js"></script><!--解析JSX语法-->
<script type="text/babel">
  class Com extends React.Component {
    state = {
      age:''
    };
    //非受控组件 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}>获取姓名</button>
          年龄：<input type="text" value={age} onChange={this.change}/>
        </div>
      );
    };
  }
  ReactDOM.render(<Com />,document.getElementById('app'));
</script>
</body>
</html>

组件生命周期：

<!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核心库-->
<script src="../js/react-dom.production.min.js"></script><!--操作DOM的react扩展库-->
<script src="../js/babel.min.js"></script><!--解析JSX语法-->
<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会先执行，但不一定先执行完毕
      console.log('之前');
      // this.get();
    }
 
    componentDidMount() {
      //进行ajax操作，获取后台数据
      console.log('之后');
    }
 
    shouldComponentUpdate(nextProps, nextState) {
      const {msg} = this.state;
 
      //如果没有
      if ({msg} !== nextState) {
        return true;
      }
      console.log('更新');
      return false;
    }
 
    componentWillUpdate() {
      console.log('更新之前');
    }
 
    componentDidUpdate() {
      console.log('更新之后');
      //再次获取数据
    }
 
    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>

希望本文所述对大家react程序设计有所帮助。

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