text: import React from 'react';
  import ReactDom from 'react-dom';
  import { HashRouter as Router,Route} from './react-router-dom';
  import Home from './component/Home'
  import User from './component/User'
  import Profile from './component/Profile'
  
  /**
   * Router代表的是路由容器
   * Route代表的是路由匹配规则
   */
  ReactDom.render(<Router>
      <Route exact={true} path='/' component={Home}/>
      <Route exact={false} path='/user' component={User}/>
      <Route exact={false} path='/profile' component={Profile}/>
      <Route></Route>
  </Router>, document.getElementById('root'));