（組件、路由）懶加載

• 懶加載也叫延遲加載，即在須要的時候進行加載，隨用隨載

  在單頁應用中，若是沒有應用懶加載，運用webpack打包後的文件將會異常的大，
  形成進入首頁時，須要加載的內容過多，延時過長，不利於用戶體驗，
  運用懶加載能夠將頁面進行劃分，按需加載頁面，能夠分擔首頁所承擔的加載壓力，減小加載用時。

• 一種代碼分塊的語法，使用 AMD 風格的 require

const Foo = resolve => require(['./Foo.vue'], resolve);
const router = new VueRouter({
  routes: [
    { path: '/foo', component: Foo }
  ]
})

//router/index.js
import Vue from 'vue'
import Router from 'vue-router'
Vue.use(Router)

const router = new Router({
  routes: [
    {
      mode: 'history',
      path: '/home',
      name: 'home',
      component:  resolve => require([URL], resolve),//懶加載
      children: [
        {
          mode: 'history',
          path: '/home/:name',
          name: 'any',
          component: resolve => require(['@/components/any'], resolve),//懶加載
        },
      ]
    },
    {
      mode: 'history',
      path: '/my',
      name: 'my',
      component: resolve => require(['@/components/my'], resolve),//懶加載,
      children: [
        {
            mode: 'history',
            path: '/my/:name',
            name: 'any',
            component: resolve => require(['@/components/any'], resolve),//懶加載
        },
      ]
    },
    {
      path: '/login',
      name: 'Login',
      component: resolve=>require(['@/components/login'],resolve)
    },
  ]
});

有一個問題：項目build之後，這個懶加載還有用嗎？