nextjs-15

Server Actions in the Next.js App Router handle server-side data mutations by defining async functions that execute securely on the server. They allow you to submit form data and update your database without creating separate API endpoints.

Server Components render on the server to fetch data directly and reduce JavaScript bundle size, while Client Components enable interactivity and state management. Next.js App Router uses file conventions like the 'use client' directive to differentiate them.

Optimize data fetching and caching in Next.js by using parallel fetching, streaming, and revalidation strategies. These techniques minimize request waterfalls and ensure your web application serves fresh data efficiently.

Middleware in the Next.js App Router secures routes and manages request/response flows before rendering completes. You can verify authentication, redirect users, and modify headers based on specific routing conditions.

Streaming and Suspense in Next.js progressively render UI segments by wrapping components in a Suspense boundary. This displays a loading state immediately while waiting for slow data fetching to resolve, improving user experience.

The Metadata API generates dynamic SEO-friendly metadata in Next.js by exporting a metadata function from your route. This function fetches data and returns tags dynamically, ensuring search engines index your web pages correctly.