14_组件_生命周期

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<div id="example"></div>
<script type="text/javascript" src="../js/react.development.js"></script>
<script type="text/javascript" src="../js/react-dom.development.js"></script>
<script type="text/javascript" src="../js/babel.min.js"></script>
<script type="text/babel">
    /*
    * 需求：自定义组件
    * 1.让指定的文本做显示/隐藏的动画
    * 2.切换时间为2S
    * 3.点击按钮从界面中移除组件页面
    * */
    // 创建虚拟dom
    class Life extends React.Component {
        constructor(props) {
            super(props);
            //初始化状态
            this.state = {
                opacity: 1
            }

        }

        distoryComponent() {
            ReactDOM.unmountComponentAtNode(document.getElementById('example'));
        }

        componentDidMount() {
            //启动循环定时器
            this.IntervalId = setInterval(function () {
                console.log('定时器执行......')
                let {opacity} = this.state
                opacity -= 0.1
                if (opacity <= 0) {
                    opacity = 1
                }
                this.setState({opacity})
            }.bind(this), 200)
        }

        componentWillUnmount() {
            //清理定时器
            clearInterval(this.IntervalId)
        }

        render() {
            const {opacity} = this.state
            return (
                <div>
                    <h2 style={{opacity}}>{this.props.msg}</h2>
                    <button onClick={this.distoryComponent}>不活了</button>
                </div>
            );
        }
    }

    // 渲染虚拟dom
    ReactDOM.render(<Life msg="react太难了！"/>, document.getElementById('example'))
</script>
</body>
</html>
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