React Interview Questions
React interview questions on rendering and reconciliation, state placement, and what effects are actually for.
Sample scorecard
React screen
What the report tells you to close:
The short version
Why the React interview is hard
React interviews increasingly test the mental model rather than the API. When components re-render, where state belongs, and what effects are genuinely for are the questions that separate candidates.
What to expect
The rounds you should rehearse
Rendering and reconciliation
what triggers a re-render, and why keys matter.
State placement
lifting it, colocating it, and the bugs caused by getting it wrong.
Effects
what belongs in one, and how much of what people put there should not be.
Avoid these
The mistakes that quietly sink candidates
Reaching for an effect to derive state that could simply be computed during render.
Using array indices as keys and then debugging mysterious list behaviour.
Adding memoisation everywhere without measuring, on the assumption it is free.
Reading the questions is not practicing them.
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FAQ
Questions, answered.
What React question comes up most?▾
How much do I need to know about reconciliation?▾
Walk in knowing exactly what they will ask.
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