JavaScript Interview Questions (Practice the Real Thing)

JavaScript interviews are really asking whether you can build and debug real frontend and Node code. These are real JS, TypeScript, and React problems - state bugs, async, types, API integration - fixed in a live cloud workspace.

Why practicing beats memorizing closures

You can recite how closures work; the interview cares whether you can fix the stale-state bug or the failed fetch in front of you. Practicing real problems builds that, across the JS, TypeScript, and React surface modern interviews actually cover.

18 real scenarios to practice

Replace LIKE Search With Postgres Full-Text SearchFullstack · SeniorMigrate an Express Route to FastifyBackend · MidFix a Node.js Memory LeakBackend · MidMigrate a React App From JavaScript to TypeScriptFullstack · MidWire React to Supabase (CRUD + Realtime)Fullstack · MidAdd a JWT Login and a Protected Route in ReactFullstack · MidFix the AI Chat That Dumps the Whole Reply at OnceFullstack · MidRepair Broken API PaginationBackend · JuniorAdd CORS Middleware to an Express APIBackend · JuniorTighten a Zod Validation Schema (TypeScript)Backend · JuniorFix a React useState Stale-State BugFullstack · JuniorFix a Blank React Dashboard (Failed Fetch)Fullstack · JuniorFix the React Search That Won't Filter (useEffect Deps)Fullstack · JuniorFix the CORS Error Blocking Your API CallsFullstack · JuniorStop the Form From Reloading the Page on SubmitFullstack · JuniorFix the Stray '0' React Renders for an Empty CountFullstack · JuniorFix the Cart Total That Concatenates Instead of AddingFullstack · JuniorFix the Leaderboard That Sorts Numbers as StringsFullstack · Junior

What JS interviews actually test

Async and state, the type system, and tracing a bug from the UI through the API. Each problem here drills one of those on a real app, so your answers come from doing.

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