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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 Header extends React.Component { constructor(props) { super(props); this.state = {favoritesite: "runoob"}; } shouldComponentUpdate() { return true; // 修改此处以允许组件更新 } changeSite = () => { this.setState({favoritesite: "google"}); } render() { return ( <div> <h1>我喜欢的网站是 {this.state.favoritesite}</h1> <button type="button" onClick={this.changeSite}>修改</button> </div> ); } } const root = ReactDOM.createRoot(document.getElementById("root")); root.render(<Header />); </script>
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