React Developer interview questions & mock practice

Common React Developer interview questions include: What is the virtual DOM, and how does React's reconciliation and diffing work? Explain useState and useEffect, and the rules of hooks. What is the difference between props and state? What does the useEffect dependency array do, and what happens if you omit it? Interviews usually run across 4 rounds — JavaScript round, React core round, Machine coding, State & performance. Practice all of them with instant AI feedback using OnJob's free mock interview.

A typical React Developer interview has 4 rounds: JavaScript round (Closures, async, the event loop and ES6+ features.); React core round (Hooks, rendering, reconciliation and component patterns.); Machine coding (Build a React component live — search, pagination or a form.); State & performance (Redux/Context, memoisation and optimisation.).

To prepare for a React Developer interview: Know hooks deeply: useState, useEffect, useRef, useMemo, useCallback and the rules that govern them. Understand the render cycle: what triggers a re-render, reconciliation, keys and how to avoid wasted renders. Practice machine coding: build an autocomplete, paginated list or form with validation from scratch. Then run a full AI mock interview on OnJob to rehearse out loud and get instant, specific feedback before the real thing.

Core React Developer skills tested in interviews include React, JavaScript, Hooks, Redux, TypeScript, Web Performance, CSS. OnJob shows you exactly which of these skills stand between you and a 100% match on every live React Developer job.

Yes. OnJob's AI mock interview is free to start (₹0) and gives you instant feedback on your answers. Pro (₹99/month) adds unlimited interview-prep AI alongside recruiter tracking and unlimited applications.