/nextjs-app-router-patterns

name: nextjs-app-router-patterns
description: Master Next.js 14+ App Router with Server Components, streaming, parallel routes, and advanced data fetching. Use when building Next.js applications, implementing SSR/SSG, or optimizing React Server Components.

Next.js App Router Patterns

Comprehensive patterns for Next.js 14+ App Router architecture, Server Components, and modern full-stack React development.

When to Use This Skill

• Building new Next.js applications with App Router
• Migrating from Pages Router to App Router
• Implementing Server Components and streaming
• Setting up parallel and intercepting routes
• Optimizing data fetching and caching
• Building full-stack features with Server Actions

Core Concepts

1. Rendering Modes

| Mode | Where | When to Use | | --------------------- | ------------ | ----------------------------------------- | | **Server Components** | Server only | Data fetching, heavy computation, secrets | | **Client Components** | Browser | Interactivity, hooks, browser APIs | | **Static** | Build time | Content that rarely changes | | **Dynamic** | Request time | Personalized or real-time data | | **Streaming** | Progressive | Large pages, slow data sources |

2. File Conventions

app/
├── layout.tsx       # Shared UI wrapper
├── page.tsx         # Route UI
├── loading.tsx      # Loading UI (Suspense)
├── error.tsx        # Error boundary
├── not-found.tsx    # 404 UI
├── route.ts         # API endpoint
├── template.tsx     # Re-mounted layout
├── default.tsx      # Parallel route fallback
└── opengraph-image.tsx  # OG image generation

Quick Start

// app/layout.tsx
import { Inter } from 'next/font/google'
import { Providers } from './providers'

const inter = Inter({ subsets: ['latin'] })

export const metadata = {
  title: { default: 'My App', template: '%s | My App' },
  description: 'Built with Next.js App Router',
}

export default function RootLayout({
  children,
}: {
  children: React.ReactNode
}) {
  return (
    <html lang="en" suppressHydrationWarning>
      <body className={inter.className}>
        <Providers>{children}</Providers>
      </body>
    </html>
  )
}

// app/page.tsx - Server Component by default
async function getProducts() {
  const res = await fetch('https://api.example.com/products', {
    next: { revalidate: 3600 }, // ISR: revalidate every hour
  })
  return res.json()
}

export default async function HomePage() {
  const products = await getProducts()

  return (
    <main>
      <h1>Products</h1>
      <ProductGrid products={products} />
    </main>
  )
}

Detailed patterns and worked examples

Detailed pattern documentation lives in `references/details.md`. Read that file when the navigation tier above is insufficient.

Best Practices

Do's

• **Start with Server Components** - Add 'use client' only when needed
• **Colocate data fetching** - Fetch data where it's used
• **Use Suspense boundaries** - Enable streaming for slow data
• **Leverage parallel routes** - Independent loading states
• **Use Server Actions** - For mutations with progressive enhancement

Don'ts

• **Don't pass serializable data** - Server → Client boundary limitations
• **Don't use hooks in Server Components** - No useState, useEffect
• **Don't fetch in Client Components** - Use Server Components or React Query
• **Don't over-nest layouts** - Each layout adds to the component tree
• **Don't ignore loading states** - Always provide loading.tsx or Suspense