Next.js (App Router)
Build modern React applications with the App Router, Server Components, and React 19

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Next.js App Router is the modern way to build React applications, introduced in Next.js 13 and refined in subsequent versions.

The App Router uses the app/ directory and brings powerful new features:

  • React Server Components - Components that render on the server by default
  • Server Actions - Call server-side functions directly from components
  • Streaming - Progressively render UI as data becomes available
  • Nested Layouts - Share UI between routes while preserving state
  • Parallel Routes - Render multiple pages simultaneously
  • Intercepting Routes - Show routes in modals or overlays

The App Router is built on React 19’s new features including:

  • The use() hook for data fetching
  • useFormStatus for form states
  • useOptimistic for optimistic updates
  • useActionState for action handling

This unit covers the App Router pattern and React 19 features for building modern Next.js applications.

Lessons in this unit:

0: ▶︎ Introduction
1: Server Actions
2: Next.js, passing an id to a server action
3: The use hook
4: use() and data fetching
5: The useFormStatus Hook
6: The useOptimistic hook
7: The useActionState hook
8: How to get the Request headers in Next.js app router
9: How to install shadcn-ui on latest Next.js beta-RC