# 1 12.全局路由拦截实现登录判断

> [导航守卫 | Vue Router](https://router.vuejs.org/zh/guide/advanced/navigation-guards.html#%E5%85%A8%E5%B1%80%E5%89%8D%E7%BD%AE%E5%AE%88%E5%8D%AB)

* #### 全局前置守卫

> 继承上章节内容,创建文件permission.js

```js
// src/permission.js

import router  from './router'
import { getToken } from '~/composables/auth'
import { toast } from '~/composables/util'


// 全局前置守卫
router.beforeEach((to, from, next) => {
    const token = getToken()
    
    // 没有登录，强制跳转到登录页面
    if(!token && to.path != '/login') {
        toast('请先登录', 'error')
        return next({ path: "/login"})
    }


    // 防止重复登录
    if(token && to.path == '/login'){
        return next({ path: from.path ? from.path: '/'})
    }
    next()
  })
```

* #### 添加到入口文件

  > main.js

```js
// main.js
import './permission'
```


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