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引出生命周期

Category: React Tutorial: React基础 Published: 2026-04-07 13:58 Views: 20 Likes: 0 Comments: 0
26_引出生命周期

<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <title>1_引出生命周期</title>
  </head>

  <body>
    <!-- 准备好一个"容器" -->
    <div id="test"></div>

    <!-- 引入react核心库 -->
    <script type="text/javascript" src="./js/react.development.js"></script>

    <!-- 引入react-dom, 用于支持react操作DOM -->
    <script
      type="text/javascript"
      src="./js/react-dom.development.js"
    ></script>

    <!-- 引入babel, 用于将jsx转为js -->
    <script type="text/javascript" src="./js/babel.min.js"></script>

    <script type="text/babel">
      // 创建组件
      // 生命周期回调函数 <=> 生命周期钩子函数 <=> 生命周期函数 <=> 生命周期钩子
      class Life extends React.Component {
        state = { opacity: 1 };

        death = () => {
          // 卸载组件
          ReactDOM.unmountComponentAtNode(document.getElementById("test"));
        };

        // 组件挂完毕
        componentDidMount() {
          console.log("componentDidMount");
          this.timer = setInterval(() => {
            // 获取原状态
            let { opacity } = this.state;
            // 减小0.1
            opacity -= 0.1;
            if (opacity <= 0) opacity = 1;
            // 设置新的透明度
            this.setState({ opacity });
          }, 200);
        }

        // 组件将要卸载 防止定时器一直运行报错
        componentWillUnmount() {
          // 清除定时器
          clearInterval(this.timer);
        }

        // 初始化渲染、状态更新之后
        render() {
          console.log("render");
          return (
            <div>
              <h2 style={{ opacity: this.state.opacity }}>
                React学不会怎么办？
              </h2>
              <button onClick={this.death}>不活了</button>
            </div>
          );
        }
      }

      // 渲染组件
      ReactDOM.render(<Life />, document.getElementById("test"));
    </script>
  </body>
</html>