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.
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.
A practical guide to fetching data in React with TypeScript — the loading/error/success states every request has, fetching in useEffect with cleanup and AbortController, avoiding race conditions, typing responses, handling HTTP errors properly, extracting a useFetch hook, mutations and refetching, and why a library like TanStack Query exists (caching, dedup, revalidation) — with common mistakes and hands-on exercises.
A practical guide to client-side routing in React with React Router and TypeScript — what a SPA router does, setting up routes, Link and NavLink navigation, nested routes and layouts with Outlet, dynamic URL params with useParams, reading and setting query strings with useSearchParams, programmatic navigation with useNavigate, redirects and protected routes, 404 handling, and lazy-loading routes — with common mistakes and hands-on exercises.
A deep, practical guide to React hooks with TypeScript — the Rules of Hooks, useState in depth (lazy init, functional updates, state as a snapshot), useEffect and the dependency array (synchronizing with external systems, cleanup, and when you don't need an effect), useRef for values and DOM nodes, useMemo and useCallback, useContext for shared state, useReducer for complex state, building your own custom hooks, common mistakes, and hands-on exercises with solutions.
A deep, practical guide to designing React components and typing their props with TypeScript — props as a read-only contract, typing props with type vs interface, optional values and defaults, children and React.ReactNode, composition patterns (wrappers, slots, specialized components), forwarding props to the DOM with rest and React.ComponentProps, discriminated-union props for variants, prop drilling and why composition beats configuration, common mistakes, and hands-on exercises with solutions.
A complete, practical guide to the React mental model every frontend developer needs — why React exists, thinking declaratively (UI = f(state)), components and JSX, typed props with TypeScript and one-way data flow, rendering lists and keys, conditional rendering, handling events, state with useState, immutable updates, the re-render model, purity and composition, common mistakes, and hands-on exercises with solutions.