import React from 'react';import ReactDOM from 'react-dom';let data = 123;class MyTitle extends React.Component {    //static propTypes = {    //    title: React.PropTypes.string.isRequired    //};//用這種方式則報錯    render() {        return <h1> {this.props.title} </h1>;    }}MyTitle.propTypes = {    title: React.PropTypes.string.isRequired};//驗證不生效ReactDOM.render(    <MyTitle title={data}/>,    document.getElementById('example'));