const router = new VueRouter({ ... })
router.beforeEach((to, from, next) => {
 // ...
})

import Vue from 'vue';
import Router from 'vue-router';
import LoginPage from '@/pages/login';
import HomePage from '@/pages/home';
import GoodsListPage from '@/pages/good-list';
import GoodsDetailPage from '@/pages/good-detail';
import CartPage from '@/pages/cart';
import ProfilePage from '@/pages/profile';
Vue.use(Router)
const router = new Router({
 routes: [
 {
  path: '/', // 默认进入路由
  redirect: '/home' //重定向
 },
 {
  path: '/login',
  name: 'login',
  component: LoginPage
 },
 {
  path: '/home',
  name: 'home',
  component: HomePage
 },
 {
  path: '/good-list',
  name: 'good-list',
  component: GoodsListPage
 },
 {
  path: '/good-detail',
  name: 'good-detail',
  component: GoodsDetailPage
 },
 {
  path: '/cart',
  name: 'cart',
  component: CartPage
 },
 {
  path: '/profile',
  name: 'profile',
  component: ProfilePage
 },
 {
  path: '**', // 错误路由
  redirect: '/home' //重定向
 },
 ]
});
// 全局路由守卫
router.beforeEach((to, from, next) => {
 console.log('navigation-guards');
 // to: Route: 即将要进入的目标 路由对象
 // from: Route: 当前导航正要离开的路由
 // next: Function: 一定要调用该方法来 resolve 这个钩子。执行效果依赖 next 方法的调用参数。
 const nextRoute = ['home', 'good-list', 'good-detail', 'cart', 'profile'];
 let isLogin = global.isLogin; // 是否登录
 // 未登录状态；当路由到nextRoute指定页时，跳转至login
 if (nextRoute.indexOf(to.name) >= 0) { 
 if (!isLogin) {
  console.log('what fuck');
  router.push({ name: 'login' })
 }
 }
 // 已登录状态；当路由到login时，跳转至home
 if (to.name === 'login') {
 if (isLogin) {
  router.push({ name: 'home' });
 }
 }
 next();
});
export default router;