在ReactDOM.render里面我们写我们的自定义组件的时候有时需要加一下子元素进去：
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <meta http-equiv="X-UA-Compatible" content="ie=edge"> <title>Document</title> </head> <body> <div id="app"></div> <script src="common/react.js"></script> <script src="common/react-dom.js"></script> <script src="https://cdn.bootcss.com/babel-core/5.8.38/browser.js"></script> <script type="text/babel"> class App extends React.Component { render() { return <div> {/*props.children获取下面4个子节点:3个元素节点和1个文字节点*/} {this.props.children.map((item,index)=> <p key={index}>{item}</p>)} </div> } } ReactDOM.render( <App> {/*加一些子元素*/} <span>rick</span> <span>zhangamie</span> <span>react</span> 2132132 </App>, document.getElementById('app') ) </script> </body> </html>