vue.js グローバル ルーティングでのナビゲーション ガードの実装

//main.js
const router= new VueRouter({
  routes:[
    {path:'/',name:'home',component:Home},
    {path:'/menu',name:'menu',component:Menu},
    {path:'/admin',name:'admin',component:Admin},
    {path:'/about',name:'about',component:About,redirect: {name:'contactLink'},children:[   //二级路由
        {path:'/about/contact',name:'contactLink',component:Contact},
        {path:'/history',name:'historyLink',component:History},
        {path:'/delivery',name:'deliveryLink',component:Delivery},
        {path:'/orderingGuide',name:'orderingGuideLink',component:OrderingGuide,redirect:{name:'phonelink'},children: [  //三级路由
            {path:'/phone',name:'phonelink',component:Phone},
            {path:'/name',name:'namelink',component:Name}
          ]},
      ]},
    {path:'/login',name:'login',component:Login},
    {path:'/register',name:'register',component:Register},
    {path:'*',redirect:'/'}
  ],
  mode:"history"
});

//main.js
//to:跳转到的路由 from:从哪个路由离开  next:显示函数
router.beforeEach((to,from,next)=>{     
  if(to.path == '/login' || to.path == '/register'){
    next();
  }else{
    alert("请先登录");
    next('/login');
  }
});