Nuxt Core

app/pages/
├── index.vue              → /
├── about.vue              → /about
├── users/
│   ├── index.vue          → /users
│   └── [id].vue           → /users/:id
└── blog/
    ├── index.vue          → /blog
    ├── [slug].vue         → /blog/:slug
    └── [...slug].vue      → /blog/* (catch-all)

<!-- app/pages/users/[id].vue -->
<script setup lang="ts">
const route = useRoute()

// Get route params
const userId = route.params.id

// Reactive (updates when route changes)
const userId = computed(() => route.params.id)

// Fetch user data
const { data: user } = await useFetch(`/api/users/${userId.value}`)
</script>

<template>
  <div>
    <h1>{{ user?.name }}</h1>
  </div>
</template>

<script setup>
const goToUser = (id: string) => {
  navigateTo(`/users/${id}`)
}

const goBack = () => {
  navigateTo(-1)  // Go back in history
}

// With options
const goToLogin = () => {
  navigateTo('/login', {
    replace: true,  // Replace current history entry
    external: false // Internal navigation
  })
}
</script>

<template>
  <!-- Declarative navigation -->
  <NuxtLink to="/about">About</NuxtLink>
  <NuxtLink :to="`/users/${user.id}`">View User</NuxtLink>

  <!-- Prefetching (default: on hover) -->
  <NuxtLink to="/dashboard" prefetch>Dashboard</NuxtLink>

  <!-- No prefetch -->
  <NuxtLink to="/admin" :prefetch="false">Admin</NuxtLink>
</template>

// app/middleware/auth.ts
export default defineNuxtRouteMiddleware((to, from) => {
  const { isAuthenticated } = useAuth()

  if (!isAuthenticated.value) {
    return navigateTo('/login')
  }
})

<!-- app/pages/dashboard.vue -->
<script setup lang="ts">
definePageMeta({
  middleware: 'auth'
})
</script>

// app/middleware/analytics.global.ts
export default defineNuxtRouteMiddleware((to, from) => {
  // Runs on every route change
  if (import.meta.client) {
    window.gtag?.('event', 'page_view', {
      page_path: to.path
    })
  }
})

<script setup lang="ts">
definePageMeta({
  title: 'Dashboard',
  middleware: ['auth'],
  layout: 'admin',
  pageTransition: { name: 'fade' },
  keepalive: true
})
</script>

<script setup lang="ts">
useSeoMeta({
  title: 'My Page Title',
  description: 'Page description for search engines',
  ogTitle: 'My Page Title',
  ogDescription: 'Page description',
  ogImage: 'https://example.com/og-image.jpg',
  ogUrl: 'https://example.com/my-page',
  twitterCard: 'summary_large_image',
  twitterTitle: 'My Page Title',
  twitterDescription: 'Page description',
  twitterImage: 'https://example.com/og-image.jpg'
})
</script>

<script setup lang="ts">
useHead({
  title: 'My Page Title',
  meta: [
    { name: 'description', content: 'Page description' },
    { property: 'og:title', content: 'My Page Title' }
  ],
  link: [
    { rel: 'canonical', href: 'https://example.com/my-page' }
  ],
  script: [
    { src: 'https://example.com/script.js', defer: true }
  ]
})
</script>

<script setup lang="ts">
const { data: post } = await useFetch(`/api/posts/${route.params.slug}`)

useSeoMeta({
  title: () => post.value?.title,
  description: () => post.value?.excerpt,
  ogImage: () => post.value?.image
})
</script>

// nuxt.config.ts
export default defineNuxtConfig({
  app: {
    head: {
      titleTemplate: '%s | My App'  // "Page Title | My App"
    }
  }
})

<!-- app/error.vue -->
<script setup lang="ts">
import type { NuxtError } from '#app'

const props = defineProps<{
  error: NuxtError
}>()

const handleError = () => {
  clearError({ redirect: '/' })
}
</script>

<template>
  <div class="error-page">
    <h1>{{ error.statusCode }}</h1>
    <p>{{ error.message }}</p>
    <button @click="handleError">Go Home</button>
  </div>
</template>

<template>
  <NuxtErrorBoundary @error="handleError">
    <template #error="{ error, clearError }">
      <div class="error-container">
        <h2>Something went wrong</h2>
        <p>{{ error.message }}</p>
        <button @click="clearError">Try again</button>
      </div>
    </template>

    <!-- Your component content -->
    <MyComponent />
  </NuxtErrorBoundary>
</template>

<script setup>
const handleError = (error: Error) => {
  console.error('Component error:', error)
  // Send to error tracking service
}
</script>

// In pages or components
throw createError({
  statusCode: 404,
  statusMessage: 'Page Not Found',
  fatal: true  // Shows error page, stops rendering
})

// Non-fatal error (shows inline)
throw createError({
  statusCode: 400,
  message: 'Invalid input'
})

const { data, error } = await useFetch('/api/users')

if (error.value) {
  // Handle error gracefully
  showError({
    statusCode: error.value.statusCode,
    message: error.value.message
  })
}

// WRONG - Won't work in production!
const apiUrl = process.env.API_URL

// CORRECT
const config = useRuntimeConfig()
const apiUrl = config.public.apiBase

// WRONG - No return, middleware continues
export default defineNuxtRouteMiddleware((to) => {
  const { isAuthenticated } = useAuth()
  if (!isAuthenticated.value) {
    navigateTo('/login')  // Missing return!
  }
})

// CORRECT
export default defineNuxtRouteMiddleware((to) => {
  const { isAuthenticated } = useAuth()
  if (!isAuthenticated.value) {
    return navigateTo('/login')  // Return stops middleware chain
  }
})

// WRONG - Not reactive
const userId = route.params.id

// CORRECT - Reactive
const userId = computed(() => route.params.id)

rm -rf .nuxt .output node_modules/.vite && bun install && bun run dev