The Complete Guide to Next.js App Router
Master the new App Router in Next.js 14 with this comprehensive guide covering layouts, loading states, and server components.
Tech Lead
The Complete Guide to Next.js App Router
Next.js 14 introduced the stable App Router, a paradigm shift in how we build React applications. Let's explore everything you need to know.
Understanding the App Router
The App Router uses React Server Components by default, offering:
- Better performance through server-side rendering
- Smaller bundle sizes by keeping code on the server
- Improved SEO with pre-rendered content
File-Based Routing
The App Router uses a folder-based routing system:
app/
├── page.tsx # /
├── about/
│ └── page.tsx # /about
├── blog/
│ ├── page.tsx # /blog
│ └── [slug]/
│ └── page.tsx # /blog/:slugLayouts and Templates
Root Layout
Every app needs a root layout:
export default function RootLayout({
children,
}: {
children: React.ReactNode;
}) {
return (
<html lang="en">
<body>{children}</body>
</html>
);
}Nested Layouts
Create layouts at any level to share UI across routes:
// app/blog/layout.tsx
export default function BlogLayout({
children,
}: {
children: React.ReactNode;
}) {
return (
<div className="blog-container">
<Sidebar />
{children}
</div>
);
}Loading UI
Add loading.tsx files for automatic loading states:
// app/blog/loading.tsx
export default function Loading() {
return <PostSkeleton />;
}Error Handling
Handle errors gracefully with error.tsx:
'use client';
export default function Error({ error, reset, }: { error: Error; reset: () => void; }) { return ( <div> <h2>Something went wrong!</h2> <button onClick={reset}>Try again</button> </div> ); }
Conclusion
The App Router represents the future of Next.js development. Embrace server components, leverage the new conventions, and build faster, more scalable applications.
Tech Lead
Full-stack developer and open-source contributor. Specializes in React, Node.js, and modern web technologies. Regular speaker at tech conferences.
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