vue-router 注意事项

1、vue-router 两种模式

（1）mode：hash，hash模式背后的原理是onhashchange事件,可以在window对象上监听这个事件。vue默认为hash模式

window.onhashchange = function(event){

    console.log(event.oldURL, event.newURL);
    let hash = location.hash.slice(1);
    document.body.style.color = hash;
｝

（2）mode：history

const router = new VueRouter({
    mode:"history",
    routes:[]
})

不怕前进，不怕后退，就怕刷新F5，如果后端没有准备的话，刷新是实实在在地去请求服务器的。

在hash模式下，前端路由修改的是#中的信息，而浏览器请求时是不带它玩的，所以没有问题，但是在history下，你可以*的修改path，当刷新时，如果服务器中没有相应的响应或者资源，会刷出一个404来。

2、嵌套路由

<script src="https://unpkg.com/vue/dist/vue.js"></script>
<script src="https://unpkg.com/vue-router/dist/vue-router.js"></script>

<div id="app">
  <p>
    <router-link to="/user/foo">/user/foo</router-link>
    <router-link to="/user/foo/profile">/user/foo/profile</router-link>
    <router-link to="/user/foo/posts">/user/foo/posts</router-link>
  </p>
  <router-view></router-view>
</div>

const User = {
  template: `
    <div class="user">
      <h2>User {{ $route.params.id }}</h2>
      <router-view></router-view>
    </div>
  `
}

const UserHome = { template: '<div>Home</div>' }
const UserProfile = { template: '<div>Profile</div>' }
const UserPosts = { template: '<div>Posts</div>' }

const router = new VueRouter({
  routes: [
    { path: '/user/:id', component: User,
      children: [
        // UserHome will be rendered inside User's <router-view>
        // when /user/:id is matched
        { path: '', component: UserHome },

        // UserProfile will be rendered inside User's <router-view>
        // when /user/:id/profile is matched
        { path: 'profile', component: UserProfile },

        // UserPosts will be rendered inside User's <router-view>
        // when /user/:id/posts is matched
        { path: 'posts', component: UserPosts }
      ]
    }
  ]
})

const app = new Vue({ router }).$mount('#app')

3、嵌套命名视图

<script src="https://unpkg.com/vue/dist/vue.js"></script>
<script src="https://unpkg.com/vue-router/dist/vue-router.js"></script>

<div id="app">
  <h1>Nested Named Views</h1>
  <router-view></router-view>
</div>

const UserSettingsNav = {
    template: `
<div class="us__nav">
  <router-link to="/settings/emails">emails</router-link>
  <br>
  <router-link to="/settings/profile">profile</router-link>
</div>
`
}
const UserSettings = {
    template: `
<div class="us">
  <h2>User Settings</h2>
  <UserSettingsNav/>
  <router-view class ="us__content"/>
  <router-view name="helper" class="us__content us__content--helper"/>
</div>
  `,
  components: { UserSettingsNav }
}

const UserEmailsSubscriptions = {
    template: `
<div>
    <h3>Email Subscriptions</h3>
</div>
  `
}

const UserProfile = {
    template: `
<div>
    <h3>Edit your profile</h3>
</div>
  `
}

const UserProfilePreview = {
    template: `
<div>
    <h3>Preview of your profile</h3>
</div>
  `
}

const router = new VueRouter({
  mode: 'history',
  routes: [
    { path: '/settings',
      // You could also have named views at tho top
      component: UserSettings,
      children: [{
          path: 'emails',
        component: UserEmailsSubscriptions
      }, {
          path: 'profile',
        components: {
            default: UserProfile,
          helper: UserProfilePreview
        }
      }]
    }
  ]
})

router.push('/settings/emails')

new Vue({
    router,
  el: '#app'
})