React · recruiter script
React screening questions for recruiters
Screening a React developer as a non-technical recruiter. Each question separates people who ship UIs from people who memorized buzzwords.
1. What is the difference between state and props in React?
- Junior
- Props come from the parent; state is internal to the component.
- Senior
- Props are read-only/immutable downward flow; state triggers re-render; lifting state up.
- Red flag
- Uses the terms interchangeably.
2. Why do React lists need a `key`, and what goes wrong with a bad one?
- Junior
- Keys help React identify list items.
- Senior
- Reconciliation identity; using array index as key breaks reorder/insert and loses state.
- Red flag
- Thinks keys are cosmetic or unnecessary.
3. What problem does `useEffect` solve, and name a common mistake with it.
- Junior
- Runs side effects after render.
- Senior
- Dependency array correctness, cleanup functions, avoiding stale closures / infinite loops.
- Red flag
- Cannot describe when it runs or why the dependency array matters.
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These questions are the free version. StepUP runs the full structured React interview and returns a scored report.