编程教程示范演示-小库网

小库网 React 实例</title>
<script src="https://lf26-cdn-tos.bytecdntp.com/cdn/expire-1-M/react/18.2.0/umd/react.production.min.js" ></script>
<script src="https://lf3-cdn-tos.bytecdntp.com/cdn/expire-1-M/react-dom/18.2.0/umd/react-dom.production.min.js"></script>
<script src="https://lf9-cdn-tos.bytecdntp.com/cdn/expire-1-M/babel-standalone/6.26.0/babel.min.js" ></script>

<div id="root"></div>
<script type="text/babel">
class Container extends React.Component {
  constructor(props) {
    super(props);
    this.state = {show: true};
  }
  delHeader = () => {
    this.setState({show: false});
  }
  render() {
    let myheader;
    if (this.state.show) {
      myheader = <Child />;
    };
    return (
      <div>
      {myheader}
      <button type="button" onClick={this.delHeader}>删除标题组建</button>
      </div>
    );
  }
}
 
class Child extends React.Component {
  componentWillUnmount() {
    alert("标题组件即将卸载。");
  }
  render() {
    return (
      <h1>Hello Runoob!</h1>
    );
  }
}
 
const root = ReactDOM.createRoot(document.getElementById("root"));
root.render(<Container />);
</script>