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: '*',  // 匹配没有注册的路由
   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;