Technical screening questions
Ask for one example per question and listen for specifics.
- When does a React component re-render, and how do you prevent wasted renders? A good answer: State and props changes, memoization and when it is not needed.
- Explain useEffect dependencies and a bug caused by them. A good answer: Stale closures and missing dependencies.
- How do you choose where state lives? A good answer: Local state vs context vs a store, avoiding prop drilling.
- How do you test a component? A good answer: Testing Library queries by role and behavior, not implementation.
- How do you improve the performance of a large list? A good answer: Virtualization, keys and pagination.
Quick screening questions
Use these when you have only a few minutes.
- How do you avoid unnecessary re-renders?
- Which state library did you use last and why?
- How do you test components?
What separates the levels
Match the level to the requirement before you submit.
- Junior: builds components from designs.
- Mid: owns features and state design.
- Senior: sets front-end architecture and performance budgets.
Red flags
Any of these is a reason to probe further.
- Only class components and no hooks.
- Cannot discuss accessibility.
- Copies Redux boilerplate without knowing why.
Tools you should hear mentioned
A React developer with real experience usually names several of these without prompting.
- React and hooks
- TypeScript
- Redux or Zustand
- React Query
- Jest and Testing Library
- Webpack or Vite
Run the call well
Ask for the last project first, then dig into the second or third question. Take notes on versions, team size and outcomes, and record them with the submission so the vendor’s later technical interview does not surprise you.
Frequently asked questions
How long should a React developer screening call take?
Fifteen to twenty minutes is enough to cover the project, three technical questions and availability, rate and work authorization.
Do recruiters need to know the technology?
Working vocabulary is enough. Use the sourcing guide for the role and listen for specifics instead of judging technical depth yourself.