tomevault-io Next.js App Router Skill
Patterns for building applications with Next.js App Router.
File-Based Routing
Basic Routes
app/
├── page.tsx # / (home)
├── about/
│ └── page.tsx # /about
├── blog/
│ └── page.tsx # /blog
├── blog/
│ └── [slug]/
│ └── page.tsx # /blog/:slug
└── shop/
└── [...slug]/
└── page.tsx # /shop/* (catch-all)
Special Files
app/
├── layout.tsx # Shared layout
├── page.tsx # Page content
├── loading.tsx # Loading UI
├── error.tsx # Error UI
├── not-found.tsx # 404 UI
├── template.tsx # Re-mount on navigation
├── default.tsx # Parallel route fallback
└── route.ts # API route
Route Groups
app/
├── (auth)/ # Group without affecting URL
│ ├── login/
│ │ └── page.tsx # /login
│ └── register/
│ └── page.tsx # /register
├── (dashboard)/
│ ├── layout.tsx # Shared dashboard layout
│ ├── settings/
│ │ └── page.tsx # /settings
│ └── profile/
│ └── page.tsx # /profile
Layouts
Root Layout
// app/layout.tsx
export default function RootLayout({
children,
}: {
children: React.ReactNode
}) {
return (
<html lang="en">
<body>
<Header />
<main>{children}</main>
<Footer />
</body>
</html>
)
}
Nested Layouts
// app/dashboard/layout.tsx
export default function DashboardLayout({
children,
}: {
children: React.ReactNode
}) {
return (
<div className="dashboard">
<Sidebar />
<div className="content">{children}</div>
</div>
)
}
Parallel Routes
// app/layout.tsx with parallel routes
export default function Layout({
children,
modal,
analytics,
}: {
children: React.ReactNode
modal: React.ReactNode // @modal slot
analytics: React.ReactNode // @analytics slot
}) {
return (
<>
{children}
{modal}
{analytics}
</>
)
}
// app/@modal/(..)photo/[id]/page.tsx
// Intercepts /photo/[id] and shows in modal
Data Fetching
Server Component Fetching
// app/users/page.tsx
async function getUsers() {
const res = await fetch('https://api.example.com/users', {
next: { revalidate: 60 }, // Revalidate every 60 seconds
})
if (!res.ok) throw new Error('Failed to fetch')
return res.json()
}
export default async function UsersPage() {
const users = await getUsers()
return (
<ul>
{users.map((user) => (
<li key={user.id}>{user.name}</li>
))}
</ul>
)
}
Caching Options
// No cache
fetch(url, { cache: 'no-store' })
// Force cache
fetch(url, { cache: 'force-cache' })
// Revalidate
fetch(url, { next: { revalidate: 60 } })
// Tag-based
fetch(url, { next: { tags: ['users'] } })
Dynamic Data
// Force dynamic rendering
export const dynamic = 'force-dynamic'
// Or use dynamic functions
import { cookies, headers } from 'next/headers'
export default async function Page() {
const cookieStore = cookies()
const headersList = headers()
return <div>Dynamic content</div>
}
Loading and Error States
Loading UI
// app/dashboard/loading.tsx
export default function Loading() {
return (
<div className="loading">
<Spinner />
<p>Loading dashboard...</p>
</div>
)
}
Streaming with Suspense
import { Suspense } from 'react'
async function SlowComponent() {
const data = await fetchSlowData()
return <div>{data}</div>
}
export default function Page() {
return (
<div>
<h1>Dashboard</h1>
<Suspense fallback={<Skeleton />}>
<SlowComponent />
</Suspense>
</div>
)
}
Error Handling
// app/dashboard/error.tsx
'use client'
export default function Error({
error,
reset,
}: {
error: Error & { digest?: string }
reset: () => void
}) {
return (
<div>
<h2>Something went wrong!</h2>
<button => reset()}>Try again</button>
</div>
)
}
Not Found
// app/not-found.tsx
export default function NotFound() {
return (
<div>
<h2>Page Not Found</h2>
<Link href="/">Return Home</Link>
</div>
)
}
// Trigger programmatically
import { notFound } from 'next/navigation'
async function getPost(id: string) {
const post = await fetchPost(id)
if (!post) notFound()
return post
}
Metadata
Static Metadata
// app/about/page.tsx
import type { Metadata } from 'next'
export const metadata: Metadata = {
title: 'About Us',
description: 'Learn more about our company',
openGraph: {
title: 'About Us',
description: 'Learn more about our company',
images: ['/og-image.png'],
},
}
Dynamic Metadata
// app/blog/[slug]/page.tsx
import type { Metadata } from 'next'
type Props = {
params: { slug: string }
}
export async function generateMetadata({ params }: Props): Promise<Metadata> {
const post = await getPost(params.slug)
return {
title: post.title,
description: post.excerpt,
}
}
Navigation
Link Component
import Link from 'next/link'
export default function Navigation() {
return (
<nav>
<Link href="/">Home</Link>
<Link href="/about">About</Link>
<Link href="/blog" prefetch={false}>Blog</Link>
<Link href={{ pathname: '/user', query: { id: '1' } }}>
User
</Link>
</nav>
)
}
Programmatic Navigation
'use client'
import { useRouter, usePathname, useSearchParams } from 'next/navigation'
export default function Navigation() {
const router = useRouter()
const pathname = usePathname()
const searchParams = useSearchParams()
const handleClick = () => {
router.push('/dashboard')
// router.replace('/dashboard')
// router.refresh()
// router.back()
}
return (
<button
Go to Dashboard
</button>
)
}
Redirect
import { redirect } from 'next/navigation'
async function Page() {
const session = await getSession()
if (!session) {
redirect('/login')
}
return <div>Protected content</div>
}
Route Handlers
API Route
// app/api/users/route.ts
import { NextRequest, NextResponse } from 'next/server'
export async function GET(request: NextRequest) {
const searchParams = request.nextUrl.searchParams
const query = searchParams.get('query')
const users = await getUsers(query)
return NextResponse.json(users)
}
export async function POST(request: NextRequest) {
const body = await request.json()
const user = await createUser(body)
return NextResponse.json(user, { status: 201 })
}
Dynamic Route Handler
// app/api/users/[id]/route.ts
export async function GET(
request: NextRequest,
{ params }: { params: { id: string } }
) {
const user = await getUser(params.id)
if (!user) {
return NextResponse.json(
{ error: 'User not found' },
{ status: 404 }
)
}
return NextResponse.json(user)
}
Integration
Used by:
frontend-developeragentfullstack-developeragent
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