<div>
  <h1>Root</h1>
  <!-- 承载子路由的容器 -->
  <router-view />
 </div>

[
 {
  path: '/profile'
  component: profile // 组件引用 此处省略引用
 },
 {
  path: '/posts'
  component: posts // 组件引用 此处省略引用
 },
]

/profile               /posts
+------------------+         +-----------------+
| Root       |         | Root      |
| +--------------+ |         | +-------------+ |
| | Profile   | | +------------> | | Posts    | |
| |       | |         | |       | |
| +--------------+ |         | +-------------+ |
+------------------+         +-----------------+

 <div>
  <h1>profile</h1>
  <!-- 承载profile子路由的容器 -->
  <router-view />
 </div>

[
 {
  path: '/profile'
  component: profile, // 此处不能少
  children: [
   {
    path: '/profile/list',
    component: profileList
   },
   {
    path: '/profile/item',
    component: profileItem
   }
  ]
 },
 ...
]

/profile/list             /profile/item
+------------------+         +-----------------+
| Root       |         | Root      |
| +--------------+ |         | +-------------+ |
| | Profile   | | +------------> | | Profile   | |
| | +----------+ | |         | | +---------+ | |
| | | list   | | |         | | | item  | | |
| | |     | | |         | | |     | | |
| | +----------+ | |         | | +---------+ | |
| +--------------+ |         | +-------------+ |
+------------------+         +-----------------+