How to Fix AI-Generated Vue.js v3.5 Router Issues (Stop Wasting Hours on Broken Routes)

// ❌ This breaks in Vue 3.5 - AI tools love this pattern
import VueRouter from 'vue-router'
import { createApp } from 'vue'

const router = new VueRouter({
  mode: 'history',
  routes: [
    { path: '/', component: Home },
    { path: '/dashboard', component: Dashboard }
  ]
})

const app = createApp(App)
app.use(router)

// ✅ Working Vue 3.5 + Router 4 setup
import { createRouter, createWebHistory } from 'vue-router'
import { createApp } from 'vue'
import Home from './components/Home.vue'
import Dashboard from './components/Dashboard.vue'

const router = createRouter({
  history: createWebHistory(), // Not 'mode: history'
  routes: [
    { path: '/', component: Home },
    { path: '/dashboard', component: Dashboard }
  ]
})

const app = createApp(App)
app.use(router)
app.mount('#app')

// ❌ AI loves this broken pattern
<script>
import { ref } from 'vue'

export default {
  setup() {
    const user = ref(null)
    
    const handleLogin = () => {
      // This breaks - no 'this' in setup()
      this.$router.push('/dashboard')
    }
    
    return { handleLogin }
  }
}
</script>

// ✅ Working Composition API router access
<script>
import { ref } from 'vue'
import { useRouter, useRoute } from 'vue-router'

export default {
  setup() {
    const router = useRouter() // Get router instance
    const route = useRoute()   // Get current route
    const user = ref(null)
    
    const handleLogin = async () => {
      // Authenticate user logic here
      await router.push('/dashboard')
      // or router.replace('/dashboard') to not save history
    }
    
    const currentPath = computed(() => route.path)
    
    return { handleLogin, currentPath }
  }
}
</script>

// ❌ This worked in Vue 2, breaks in Vue 3.5
router.beforeEach((to, from, next) => {
  if (to.meta.requiresAuth && !this.isAuthenticated) {
    next('/login')
  } else {
    next()
  }
})

// ✅ Working Vue 3.5 route guards
import { useAuthStore } from '@/stores/auth' // Pinia example

router.beforeEach((to, from) => {
  const authStore = useAuthStore()
  
  if (to.meta.requiresAuth && !authStore.isAuthenticated) {
    return '/login' // Return path instead of next()
  }
  
  // Return nothing or true to proceed
})

// Alternative: using next() correctly
router.beforeEach((to, from, next) => {
  const authStore = useAuthStore()
  
  if (to.meta.requiresAuth && !authStore.isAuthenticated) {
    next('/login')
    return // Don't forget this return!
  }
  
  next() // Always call next() if using this pattern
})

// ❌ AI-generated broken param access
<template>
  <div>User ID: {{ $route.params.id }}</div>
</template>

<script>
export default {
  created() {
    console.log(this.$route.params.id) // Works in template, breaks in script
  }
}
</script>

// ✅ Working Vue 3.5 parameter access
<template>
  <div>User ID: {{ userId }}</div>
</template>

<script>
import { computed } from 'vue'
import { useRoute } from 'vue-router'

export default {
  setup() {
    const route = useRoute()
    
    // Reactive parameter access
    const userId = computed(() => route.params.id)
    
    // Watch for parameter changes
    watch(() => route.params.id, (newId) => {
      console.log('User ID changed to:', newId)
      // Fetch new user data
    })
    
    return { userId }
  }
}
</script>

// ❌ AI generates this broken lazy loading
const routes = [
  {
    path: '/dashboard',
    component: () => import('./Dashboard.vue') // Breaks with some bundlers
  }
]

// ✅ Working lazy loading for Vue 3.5 + Vite
const routes = [
  {
    path: '/',
    name: 'Home',
    component: () => import('../views/HomeView.vue')
  },
  {
    path: '/dashboard',
    name: 'Dashboard', 
    component: () => import('../views/DashboardView.vue'),
    meta: { requiresAuth: true }
  },
  {
    path: '/profile/:id',
    name: 'Profile',
    component: () => import('../views/ProfileView.vue'),
    props: true // Pass route params as props
  }
]

// router/index.js
import { createRouter, createWebHistory } from 'vue-router'
import { useAuthStore } from '@/stores/auth'

const routes = [
  {
    path: '/',
    name: 'Home',
    component: () => import('../views/HomeView.vue')
  },
  {
    path: '/login',
    name: 'Login',
    component: () => import('../views/LoginView.vue')
  },
  {
    path: '/dashboard',
    name: 'Dashboard',
    component: () => import('../views/DashboardView.vue'),
    meta: { requiresAuth: true }
  },
  {
    path: '/profile/:id',
    name: 'Profile',
    component: () => import('../views/ProfileView.vue'),
    props: true,
    meta: { requiresAuth: true }
  },
  {
    path: '/:pathMatch(.*)*',
    name: 'NotFound',
    component: () => import('../views/NotFoundView.vue')
  }
]

const router = createRouter({
  history: createWebHistory(),
  routes
})

// Working authentication guard
router.beforeEach((to) => {
  const authStore = useAuthStore()
  
  if (to.meta.requiresAuth && !authStore.isAuthenticated) {
    return '/login'
  }
})

export default router