Next.js
Master the Next.js App Router end to end: layouts and routing, server vs. client components, data fetching and caching, Server Actions, streaming, middleware and sessions. Every problem is a real defect in a working app, fixed the way the framework intends. Runs from Easy to Hard on a seeded in-memory store, graded on tested behaviour. Each topic closes with a Star Problem that combines everything in it into one screen: solve the full set if you want the practice, or clear just the Star Problem and move on to the next section.
Next.js 16
Node.js 24Routing & Layouts
The file system is the router, and layouts stop the app repeating itself. Nested layouts, route groups, the metadata API, and per-segment loading, error and not-found states. The lesson is scope: which segment owns the chrome, and which owns the failure.
Bakery Storefront
Travel Guide Sections
Clinic Portal
Bookshop Site
Navigation & Linking
Moving between routes without throwing away the page. Client navigation, active state derived from the pathname, prefetching, dynamic segments, and filter state held in the URL. If a screen can't be reproduced from its link, it isn't finished.