Nextjs Patterns

Next.js Development Patterns

When to Use This Skill

• Building Next.js applications with App Router
• Implementing Server Components and Server Actions
• Creating full-stack React applications
• SEO-optimized web applications
• Following Next.js 14+ best practices

Target Agents

• nextjs-expert - Primary user for Next.js development
• react-typescript-expert - TypeScript React patterns
• frontend-developer - Full-stack web development

Core Patterns

1. App Router Structure

app/
├── (marketing)/
│   ├── page.tsx           # /
│   └── about/
│       └── page.tsx       # /about
├── (dashboard)/
│   ├── layout.tsx
│   └── dashboard/
│       └── page.tsx       # /dashboard
├── api/
│   └── users/
│       └── route.ts       # API route
├── layout.tsx             # Root layout
└── page.tsx              # Home page

2. Server Components (Default)

// app/posts/page.tsx
async function getPosts() {
  const res = await fetch('https://api.example.com/posts', {
    next: { revalidate: 3600 } // ISR: revalidate every hour
  })
  return res.json()
}

export default async function PostsPage() {
  const posts = await getPosts()

  return (
    <div>
      <h1>Posts</h1>
      {posts.map((post) => (
        <article key={post.id}>
          <h2>{post.title}</h2>
          <p>{post.excerpt}</p>
        </article>
      ))}
    </div>
  )
}

3. Client Components

'use client'

import { useState } from 'react'

export default function Counter() {
  const [count, setCount] = useState(0)

  return (
    <button => setCount(count + 1)}>
      Count: {count}
    </button>
  )
}

4. Server Actions

// app/actions.ts
'use server'

import { revalidatePath } from 'next/cache'

export async function createPost(formData: FormData) {
  const title = formData.get('title')
  const content = formData.get('content')

  await db.post.create({
    data: { title, content }
  })

  revalidatePath('/posts')
  return { success: true }
}

// app/posts/new/page.tsx
import { createPost } from '@/app/actions'

export default function NewPost() {
  return (
    <form action={createPost}>
      <input name="title" required />
      <textarea name="content" required />
      <button type="submit">Create Post</button>
    </form>
  )
}

5. Dynamic Routes & Params

// app/posts/[id]/page.tsx
interface PageProps {
  params: { id: string }
  searchParams: { [key: string]: string | string[] | undefined }
}

export async function generateMetadata({ params }: PageProps) {
  const post = await getPost(params.id)
  return { title: post.title }
}

export default async function PostPage({ params }: PageProps) {
  const post = await getPost(params.id)
  return <article>{/* post content */}</article>
}

export async function generateStaticParams() {
  const posts = await getPosts()
  return posts.map((post) => ({ id: post.id }))
}

6. API Routes

// app/api/users/route.ts
import { NextRequest, NextResponse } from 'next/server'

export async function GET(request: NextRequest) {
  const users = await db.user.findMany()
  return NextResponse.json(users)
}

export async function POST(request: NextRequest) {
  const body = await request.json()
  const user = await db.user.create({ data: body })
  return NextResponse.json(user, { status: 201 })
}

7. Middleware

// middleware.ts
import { NextResponse } from 'next/server'
import type { NextRequest } from 'next/server'

export function middleware(request: NextRequest) {
  const token = request.cookies.get('token')

  if (!token && request.nextUrl.pathname.startsWith('/dashboard')) {
    return NextResponse.redirect(new URL('/login', request.url))
  }

  return NextResponse.next()
}

export const config = {
  matcher: ['/dashboard/:path*']
}

8. Data Fetching Patterns

// Parallel Data Fetching
async function getData() {
  const [posts, users] = await Promise.all([
    fetch('https://api.example.com/posts'),
    fetch('https://api.example.com/users')
  ])

  return {
    posts: await posts.json(),
    users: await users.json()
  }
}

// Sequential (when dependent)
async function getPostAndComments(id: string) {
  const post = await getPost(id)
  const comments = await getComments(post.id)
  return { post, comments }
}

9. Streaming & Suspense

import { Suspense } from 'react'

export default function Page() {
  return (
    <div>
      <h1>Dashboard</h1>
      <Suspense fallback={<LoadingSkeleton />}>
        <Posts />
      </Suspense>
      <Suspense fallback={<LoadingSkeleton />}>
        <Analytics />
      </Suspense>
    </div>
  )
}

10. Image Optimization

import Image from 'next/image'

export default function Profile() {
  return (
    <Image
      src="/profile.jpg"
      alt="Profile"
      width={500}
      height={500}
      priority
      quality={90}
    />
  )
}

Best Practices

1. Use Server Components by default
2. Add 'use client' only when needed (interactivity)
3. Leverage Server Actions for mutations
4. Implement proper caching strategies
5. Use Suspense for streaming
6. Optimize images with next/image
7. Implement proper SEO metadata
8. Use TypeScript for type safety
9. Follow App Router conventions
10. Implement error boundaries

Additional Resources

• caching.md - Caching strategies
• authentication.md - Auth patterns
• deployment.md - Deployment best practices