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React旧有生命周期和新生命周期的解析

news 来源：原创 2024/4/27 15:16:04

React组件生命周期（旧有格式）
在这里插入图片描述
新的生命周期

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>
    <!-- 制作组件 -->
    <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>