router 配置按需加载对应的组件，配置active

 const routes = [
   {
     path: '/',
     component: App,
     children: [
       {path: '/index/:type', name: 'index', component: Index},
       {path: '/home', name: 'home', component: Home},
       {path: '/HomeUserInfo/:uid', name: 'homeUserInfo', component: HomeUserInfo},
       {path: '/article/:id', name: 'article', component: Article},
       {path: '/addmsg', name: 'addMsg', component: AddMsg},
       {path: '/search/:types', name: 'searchresult', component: SearchResult},
       {path: '/login', name: 'login', component: Login},
       {path: '/register', name: 'register', component: Register},
       {path: '/modif', name: 'Modifi', component: Modifi},
       {path: '/admin', name: 'Admin', component: Admin}
     ]
   }
 ]
 const router = new VueRouter({
   routes: routes, // short for routes: routes
   linkActiveClass: 'active',  // router-link的选中状态的class，也有一个默认的值
   history: true
 })