React旧有生命周期和新生命周期的解析

港控/mmm° 2023-09-29 17:08 31阅读 0赞

React组件生命周期（旧有格式）  
![在这里插入图片描述][7c410c56175a472c9d5df990d92fcf9c.png]  
新的生命周期  
![在这里插入图片描述][c98a8904fd324aa3a4191574842da591.png]  
下面是旧有声明周期的案例演示：

<!DOCTYPE html>
    <html lang="en">
    <head>
        <meta charset="UTF-8">
        <meta http-equiv="X-UA-Compatible" content="IE=edge">
        <meta name="viewport" content="width=device-width, initial-scale=1.0">
        <title>Document</title>
        <script src="../js/react.development.js"></script>
        <script src="../js/react-dom.development.js"></script>
        <script src="../js/babel.min.js"></script>
        <script src="../js/prop-types.js"></script>
    </head>
    <body>
        <div id="test"></div>
        
        <script type="text/babel">
            class Count extends React.Component{
          
                //构造器;
                constructor(props){
          
                    console.log('我是构造器');
                    super(props);
                    //初始状态；因为在构造器内部，所以，需要加this关键字;
                    this.state={
          count:0};
                }
                //组件将要挂载;
                componentWillMount(){
          
                    console.log('组件将要挂载...');
                }
                //加1按钮的回调;
                add = () => {
          
                    //获取原始状态;
                    const{
          count}=this.state;
                    //更新状态;
                    this.setState({
          count:count+1});
                }
                death= () => {
          
                    ReactDOM.unmountComponentAtNode(document.getElementById('test'));
                }
                //挂载完毕;
                componentDidMount(){
          
                    console.log('组件挂载完毕...');
                }
                //卸载组件;
                componentWillUnmount(){
          
                    console.log('组件卸载了...');
                }
                //组件更新
                shouldComponentUpdate(){
          
                    console.log('shouldComponentUpdate...');
                    return true;
                }
                //组件将要更新
                componentWillUpdate(){
          
                    console.log('componentWillUpdate...');
                }
                //组件更新
                componentDidUpdate(){
          
                    console.log('componentDidUpdate...');
                }
                //强制更新;
                force= () => {
          
                    this.forceUpdate();
                }
                //渲染;
                render(){
          
                    console.log('render');
                    const {
          count}=this.state;  //这句不要忘了加
                    return(
                        <div>
                            <h2>当前求和是：{
          count}</h2>
                            <button onClick={
          this.add}>按钮测试</button>
                            <button onClick={
          this.death}>卸载组件</button>
                            <button onClick={
          this.force}>强制更新</button>
                        </div>
                    );
                }
            }
            //调用;
            ReactDOM.render(<Count/>,document.getElementById('test'));
        </script>
    </body>
    </html>

[7c410c56175a472c9d5df990d92fcf9c.png]: https://img-blog.csdnimg.cn/7c410c56175a472c9d5df990d92fcf9c.png
[c98a8904fd324aa3a4191574842da591.png]: https://img-blog.csdnimg.cn/c98a8904fd324aa3a4191574842da591.png