Introduction to route guard functions in Vue documentation

Vue is a popular front-end framework that provides many powerful features, one of which is the route guard function. The route guard function is an important feature of Vue routing and is used to execute control logic when navigating to or leaving a route. Route guard functions allow you to control the reading and modification of routes, as well as route navigation based on various conditions. This article will introduce the route guard function in the Vue document to help you understand the role and usage of the route guard function in Vue.

Route guard functions can be divided into three categories: global front guards, global post hooks and route-exclusive guards. Below we introduce these three types of guards respectively.

Global pre-guard:

Global pre-guard can be executed before any route jump. You can register a global prefix guard on the Vue router object so that it takes effect on every route in the entire project. Register a global beforeEach guard on the Vue router object using the beforeEach method, as shown below:

router.beforeEach((to, from, next) => {
  // to: 即将进入的目标路由对象
  // from: 当前导航正要离开的路由对象
  // next: 下一步执行钩子函数，如果全部执行完了，则返回空或一个true值
})

The simplest usage is to start the outbound operation by calling the next() method. If you want to cancel navigation (for example, the user does not have permission to access), return false or a string or an Error instance, which will terminate the navigation and switch directly to the corresponding route. For example, the following guard terminates navigation if the user is not logged in:

router.beforeEach((to, from, next) => {
  const isAuthenticated = store.getters.isAuth
  if (!isAuthenticated && to.path !== '/login') {
    next('/login')
  } else {
    next()
  }
})

Global posthook:

Global posthook will be executed after the navigation is confirmed. This guard does not accept a next function and does not change the navigation itself:

router.afterEach((to, from) => {
  // to: 要进入的目标路由
  // from: 正在离开的路由
})

Route-exclusive guards:

Route-exclusive guards can be set in the route configuration, which means you can Define different front and back guards to handle different routes. You can use the beforeEnter guard to configure an exclusive guard function for a specific route (unlike the global guard, there is no need to register the guard on the Router object). The beforeEnter guard will only fire if it exists in the route-exclusive configuration.

const router = new VueRouter({
  routes: [
    {
      path: '/user/:id',
      component: User,
      beforeEnter: (to, from, next) => {
        // ...
      }
    }
  ]
})

The logic performed in the route exclusive guard is very similar to the logic in the global front guard function, but the front guard allows you to perform the same logic for all routes, while the route exclusive guard can Some routes define specific logic.

Summary:

The route guard function is an important part of Vue routing, which provides you with the ability to control route navigation. Global front guards, global post hooks and route-exclusive guards are three different guard types, each with different purposes and characteristics. When using Vue routing, a deeper understanding and use of these different types of guards can help you gain better control over route navigation and develop more flexible front-end applications.

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