next-best-practices

Next.js App Router best practices for data fetching involve making requests directly inside React Server Components to leverage server-side execution. Use Server Actions for mutations and Route Handlers for API endpoints, ensuring data flows correctly across RSC boundaries without hydration errors.

Hydration errors from invalid React Server Component boundaries are fixed by correctly structuring your component tree and data flow. Apply Next.js App Router file conventions and wrap asynchronous components in Suspense boundaries to manage loading states and prevent client-server markup mismatches.

Optimize images, fonts, and scripts in Next.js by utilizing the framework's built-in optimization features. Apply App Router best practices to automatically handle asset bundling, script loading strategies, and font optimization, resulting in improved Core Web Vitals and application performance.

Parallel and intercepting routes in Next.js are needed when building advanced UI patterns like modals that load within the current layout context. They allow rendering multiple routes simultaneously and intercepting navigation to display content without a full page transition.

Error handling and metadata generation in Next.js App Router are set up by defining error boundaries for graceful runtime management and exporting metadata objects from route files. This ensures robust error recovery and dynamic SEO tag generation without blocking the rendering pipeline.