From nextjs-expert
Guides React Server Components in Next.js: server vs client distinction, 'use client' directive, component boundaries, composition patterns, and data fetching.
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React Server Components (RSC) allow components to render on the server, reducing client-side JavaScript and enabling direct data access. In Next.js App Router, all components are Server Components by default.
React Server Components (RSC) allow components to render on the server, reducing client-side JavaScript and enabling direct data access. In Next.js App Router, all components are Server Components by default.
Server Components run only on the server:
// app/users/page.tsx (Server Component - default)
async function UsersPage() {
const users = await db.user.findMany() // Direct DB access
return (
<ul>
{users.map(user => (
<li key={user.id}>{user.name}</li>
))}
</ul>
)
}
Benefits:
Add 'use client' directive for interactivity:
// components/counter.tsx
'use client'
import { useState } from 'react'
export function Counter() {
const [count, setCount] = useState(0)
return (
<button onClick={() => setCount(count + 1)}>
Count: {count}
</button>
)
}
Use Client Components for:
useState, useEffect, useReduceronClick, onChange)window, document)Think of the component tree as having a "client boundary":
Server Component (page.tsx)
├── Server Component (header.tsx)
├── Client Component ('use client') ← boundary
│ ├── Client Component (child)
│ └── Client Component (child)
└── Server Component (footer.tsx)
Key rules:
children to Client ComponentsFetch data in Server Component, pass to Client:
// app/products/page.tsx (Server)
import { ProductList } from './product-list'
export default async function ProductsPage() {
const products = await getProducts()
return <ProductList products={products} />
}
// app/products/product-list.tsx (Client)
'use client'
export function ProductList({ products }: { products: Product[] }) {
const [filter, setFilter] = useState('')
const filtered = products.filter(p =>
p.name.includes(filter)
)
return (
<>
<input onChange={e => setFilter(e.target.value)} />
{filtered.map(p => <ProductCard key={p.id} product={p} />)}
</>
)
}
Pass Server Components through children prop:
// components/client-wrapper.tsx
'use client'
export function ClientWrapper({ children }: { children: React.ReactNode }) {
const [isOpen, setIsOpen] = useState(false)
return (
<div>
<button onClick={() => setIsOpen(!isOpen)}>Toggle</button>
{isOpen && children} {/* Server Component content */}
</div>
)
}
// app/page.tsx (Server)
import { ClientWrapper } from '@/components/client-wrapper'
import { ServerContent } from '@/components/server-content'
export default function Page() {
return (
<ClientWrapper>
<ServerContent /> {/* Renders on server! */}
</ClientWrapper>
)
}
Use multiple children slots:
// components/dashboard-shell.tsx
'use client'
interface Props {
sidebar: React.ReactNode
main: React.ReactNode
}
export function DashboardShell({ sidebar, main }: Props) {
const [collapsed, setCollapsed] = useState(false)
return (
<div className="flex">
{!collapsed && <aside>{sidebar}</aside>}
<main>{main}</main>
</div>
)
}
Server Components can be async:
// app/posts/page.tsx
export default async function PostsPage() {
const posts = await fetch('https://api.example.com/posts')
.then(res => res.json())
return (
<ul>
{posts.map(post => (
<li key={post.id}>{post.title}</li>
))}
</ul>
)
}
Fetch multiple resources in parallel:
export default async function DashboardPage() {
const [user, posts, analytics] = await Promise.all([
getUser(),
getPosts(),
getAnalytics(),
])
return (
<Dashboard user={user} posts={posts} analytics={analytics} />
)
}
Stream slow components:
import { Suspense } from 'react'
export default function Page() {
return (
<div>
<Header /> {/* Renders immediately */}
<Suspense fallback={<PostsSkeleton />}>
<SlowPosts /> {/* Streams when ready */}
</Suspense>
</div>
)
}
Use Server Component when:
Use Client Component when:
useState, useReducer)useEffect)'use client' unnecessarily - it increases bundle sizeFor detailed patterns, see:
references/server-vs-client.md - Complete comparison guidereferences/composition-patterns.md - Advanced compositionexamples/data-fetching-patterns.md - Data fetching examplesnpx claudepluginhub davepoon/buildwithclaude --plugin nextjs-expertGuides using Next.js Server Components for data fetching, direct DB access, Server vs Client decisions, and Server Actions in data-intensive apps.
React Server Components patterns for Next.js 16. Server vs Client boundaries, async components, data fetching, serialization rules, streaming with Suspense.
Enables React Server Components to eliminate client JavaScript and directly access data in server components. Provides patterns for splitting server and client components using 'use client' directive.