nextjs-15

Next.js 15 App Router uses file-system based routing within the app directory. Create layout files for shared UI, organize routes in folders with page.js files, and use route groups with parentheses for logical organization without affecting URLs. This standardizes scalable app structure with consistent conventions.

Next.js 15 supports parallel and streaming data fetching patterns. Use async components to fetch data server-side, implement streaming with Suspense boundaries for progressive rendering, and leverage route handlers for API endpoints. These strategies optimize performance and reduce client-side loading.

Server actions in Next.js 15 are async functions defined with the 'use server' directive that run on the server. Attach them directly to form elements for secure form submission and data operations without API routes, simplifying authentication and data validation on the server.

Yes, Next.js 15 App Router makes server components the default. They work across layouts, pages, and route groups, enabling server-side rendering, direct database access, and secure operations. This provides consistent patterns for building scalable applications with minimal client JavaScript.

Use route handlers for RESTful API endpoints and webhooks; use server actions for form submissions and mutations triggered from client or server components. Route handlers provide explicit HTTP methods; server actions offer simpler syntax for data operations tied directly to components.

The App Router standardizes modern patterns for routing, server actions, and data fetching, replacing the Pages Router. It provides clearer file structure, native server component support, and integrated server actions, reducing boilerplate and enabling faster, more maintainable app scaffolding.