路由懒加载的三种写法

第一种懒加载方式：

import Vue from 'vue'
import Router from 'vue-router'

const login= () => import('./components/login.vue')
const routerB = () => import('./components/routerB.vue')
const routerC  = () => import('./components/routerC.vue')
const routerD = () => import('./components/routerD.vue')
Vue.use(Router)
const router = new Router({
  routes: [
    { path: '/', redirect: '/login' },
    { path: '/login', component: login},
    {
      path: '/routerB ',
      component: routerB ,
      redirect: '/routerB ',
      children: [
        { path: '/routerC  ', component: routerC },
        { path: '/routerD ', component: routerD }
      ]
    }
  ]
})
// 挂载路由导航守卫
router.beforeEach((to, from, next) => 
  if (to.path === '/login') return next()
  // 获取token
  const token = window.sessionStorage.getItem('token')
  if (!token) return next('/login')
  next()
})
export default router

第二种懒加载方式：

import Vue from 'vue'
import VueRouter from 'vue-router'
Vue.use(VueRouter)
const routes = [
  {
    path: '/login',
    name: 'login',
    component: () => import('@/views/login')
  },
  {
    path: '/',
    component: () => import('@/views/routerB'),
    children: [
    ]
  }
]
const router = new VueRouter({
  routes
})
export default router

第三种懒加载方式：

import Vue from 'vue'
import VueRouter from 'vue-router'
Vue.use(VueRouter)
const routes = [
  {
    path: '/login',
    name: 'login',
    component: resolve => require(['@/views/login'],resolve)
  },
  {
    path: '/',
    component: resolve => require(['@/views/routerB '],resolve),
    children: [
      {
        path: '',
        name: 'routerC',
        component: resolve => require(['@/views/routerC'],resolve),
        meta: {
          keepAlive: true
        }
      }
]
const router = new VueRouter({
  routes
})
export default router