How to use Vue Router guards

import { createRouter, createWebHistory } from 'vue-router'

const router = createRouter({
  history: createWebHistory(),
  routes: [
    { path: '/', component: Home },
    { path: '/login', component: Login },
    { path: '/dashboard', component: Dashboard, meta: { requiresAuth: true } },
    { path: '/admin', component: Admin, meta: { requiresAuth: true, role: 'admin' } }
  ]
})

router.beforeEach((to, from, next) => {
  const isAuthenticated = localStorage.getItem('authToken')
  const userRole = localStorage.getItem('userRole')

  if (to.meta.requiresAuth && !isAuthenticated) {
    next('/login')
  } else if (to.meta.role && userRole !== to.meta.role) {
    next('/')
  } else {
    next()
  }
})

export default router

const routes = [
  {
    path: '/profile',
    component: Profile,
    beforeEnter: (to, from, next) => {
      if (isUserLoggedIn()) {
        next()
      } else {
        next('/login')
      }
    }
  },
  {
    path: '/admin',
    component: Admin,
    beforeEnter: (to, from, next) => {
      if (hasAdminAccess()) {
        next()
      } else {
        next({ name: 'Forbidden' })
      }
    }
  }
]

<script>
export default {
  name: 'EditPost',

  beforeRouteEnter(to, from, next) {
    fetchPost(to.params.id).then(post => {
      next(vm => {
        vm.post = post
      })
    })
  },

  beforeRouteUpdate(to, from, next) {
    this.post = null
    fetchPost(to.params.id).then(post => {
      this.post = post
      next()
    })
  },

  beforeRouteLeave(to, from, next) {
    if (this.hasUnsavedChanges) {
      const answer = window.confirm('You have unsaved changes. Leave anyway?')
      next(answer)
    } else {
      next()
    }
  }
}
</script>

import { useAuthStore } from '@/stores/auth'

router.beforeEach(async (to, from, next) => {
  const authStore = useAuthStore()

  if (to.meta.requiresAuth) {
    if (!authStore.isAuthenticated) {
      try {
        await authStore.checkAuth()
        next()
      } catch (error) {
        next({
          path: '/login',
          query: { redirect: to.fullPath }
        })
      }
    } else {
      next()
    }
  } else {
    next()
  }
})

<script setup>
import { onBeforeRouteLeave, onBeforeRouteUpdate } from 'vue-router'
import { ref } from 'vue'

const hasUnsavedChanges = ref(false)

onBeforeRouteLeave((to, from, next) => {
  if (hasUnsavedChanges.value) {
    const answer = window.confirm('Discard unsaved changes?')
    next(answer)
  } else {
    next()
  }
})

onBeforeRouteUpdate(async (to, from, next) => {
  if (to.params.id !== from.params.id) {
    await loadData(to.params.id)
  }
  next()
})
</script>

router.afterEach((to, from) => {
  // Update page title
  document.title = to.meta.title || 'My App'

  // Track page view
  if (window.gtag) {
    window.gtag('config', 'GA_MEASUREMENT_ID', {
      page_path: to.fullPath
    })
  }

  // Scroll to top
  window.scrollTo(0, 0)
})