A curated bank of frontend interview questions with strong, concise answers — JavaScript and the language, HTML/CSS and accessibility, the browser and the network, performance and Core Web Vitals, React (hooks, rendering, state), Next.js (Server Components, rendering, caching), and behavioral/design questions — each with a 'Show answer' you can self-test against, plus how to approach the interview itself.
An expert guide to taking a Next.js App Router app to production with TypeScript — authentication done in layers (middleware, Data Access Layer, sessions with httpOnly cookies), environment variables and keeping secrets server-only, performance with next/image, next/font, dynamic imports and bundle analysis, error handling with error.tsx and not-found, and deployment on Vercel or self-hosted with standalone output — with common mistakes and exercises.
An expert guide to the Next.js App Router's powerful routing features with TypeScript — route groups for organization and multiple root layouts, dynamic and catch-all segments with generateStaticParams, parallel routes with named slots, intercepting routes for modals, route handlers (route.ts) as API endpoints, middleware for auth and redirects, template vs layout, and metadata files — with common mistakes and exercises.
An expert guide to changing data in the Next.js App Router with Server Actions and TypeScript — what a Server Action is and how 'use server' works, form actions and progressive enhancement, useActionState for form state and validation errors, useFormStatus for pending UI, useOptimistic for optimistic updates, revalidating and redirecting after a mutation, binding extra arguments, calling actions outside forms, and the security rules that matter because actions are public endpoints — with common mistakes and exercises.
An expert guide to how the Next.js App Router renders and caches — static vs dynamic rendering and what triggers each, the four caching layers (Request Memoization, Data Cache, Full Route Cache, Router Cache), fetch caching in Next 15+ (uncached by default), time-based and on-demand revalidation with revalidateTag/revalidatePath, unstable_cache for non-fetch data, route segment config, streaming with Suspense and loading.tsx, and Partial Prerendering — with common mistakes and exercises.
A practical introduction to Next.js and the App Router with TypeScript — what a React framework adds on top of React, file-based routing with folders and page.tsx, layouts and nested routes, Server vs Client Components, fetching data on the server, rendering strategies (SSG/SSR/ISR), navigation with next/link and useRouter, special files (loading, error, not-found), the Metadata API for SEO, and a first look at Server Actions and next/image — with common mistakes and hands-on exercises.