Interview Prep
React interview questions and how to answer them
React interviews test both fluency and depth. Hooks questions trip people up at every level. The architecture and performance questions separate strong candidates from people who have only worked in small codebases. These are the questions that show up most.
PrepVault maps your skills to the job and surfaces the questions you need to study. Free to start.
React interview questions and how to answer them
How should persisted store state be designed?
persist small allowlist. version and migrate. avoid sensitive stale data
How can Redux or Zustand stores be tested?
test reducers and selectors. call store actions. reset state between tests
Why should React render logic be pure?
same input same output. render may repeat. effects after commit
How would this test component help verify an error boundary?
controlled render failure. assert fallback UI. focused boundary test
What are retry strategies in data fetching?
error-aware retries. idempotency matters. backoff and user impact
How do Redux and Zustand differ from React Context?
context distributes values. stores manage shared state. selectors and subscriptions
How would you explain why reducing JavaScript bundle size improves performance?
Smaller bundles download faster. Less JavaScript parses and executes faster. Mobile devices are more affected. Code splitting can reduce initial bundle size. Performance includes execution not just download
How should pagination or infinite loading be modeled in React data fetching?
page or cursor in key. append pages carefully. separate loading more state
How does generateStaticParams affect static generation for dynamic routes in the Next.js App Router?
dynamic route params. build-time generation. known page set. App Router replacement
What are React Server Components and how do they differ from traditional React components?
Render only on the server, add no JavaScript to client bundle. Can directly access databases, file systems, and secrets. Cannot use useState, useEffect, event handlers, or browser APIs. Next.js App Router defaults all components to server. Add use client to opt into client-side capabilities
Common mistakes
- Shaky on state versus props under pressure
- Vague on why a re-render happens
- Reaching for useEffect when you don't need it
What interviewers weigh
- Depth on hooks and rendering
- How you reason about performance
- Whether you've worked beyond small codebases