React Interview Questions

Beginner

What is React and JSX? Props vs state? Virtual DOM? Keys? Controlled vs uncontrolled? useState, useEffect, Context, Router basics.

Intermediate

useMemo vs useCallback? useReducer? Custom hooks? Thunks vs RTK Query? Protected routes? JWT refresh? Code splitting? Testing Library?

Advanced

Reconciliation internals? Re-render causes and fixes? Context vs Redux? Scalable folder design? API service design? Micro-frontends? Bundle strategy?

Key Points

• Answer with mechanism plus tradeoff plus example.
• Pair each answer with tutorials 01 to 24.
• 60 curated questions covering the full series.