Testing, TypeScript & Deployment
React Interview Questions for Freshers
React interviews for freshers in India concentrate on a predictable set of topics: the virtual DOM, state versus props, hooks and their rules, keys, useEffect dependencies, and how to avoid unnecessary re-renders.
What is Interview Questions for Freshers in React?
React interviews for freshers in India concentrate on a predictable set of topics: the virtual DOM, state versus props, hooks and their rules, keys, useEffect dependencies, and how to avoid unnecessary re-renders.
Key points to remember
- Be ready to write a counter, a controlled form and a fetch-with-loading component on a whiteboard.
- Expect a practical question: "this component re-renders too often — why?"
- Know which parts of your own project you would change and why.
Frequently asked, with the answer in one line
| Question | Short answer |
|---|---|
| What is the virtual DOM? | An in-memory JavaScript tree React diffs to compute minimal real-DOM updates. |
| State vs props? | State is owned and mutable inside the component; props come from the parent and are read-only. |
| Why are keys needed? | To match list items between renders so React updates the right nodes and preserves state. |
| useEffect vs useLayoutEffect? | useEffect runs after paint; useLayoutEffect runs before it and blocks painting. |
| useMemo vs useCallback? | useMemo caches a value, useCallback caches a function reference. |
| Why can hooks not be conditional? | React identifies hooks by call order, so a skipped call shifts every later hook. |
| Controlled vs uncontrolled input? | Controlled reads its value from state; uncontrolled keeps it in the DOM and is read via a ref. |
| What is prop drilling and how do you avoid it? | Passing props through components that do not use them; fix with composition or context. |
| What is reconciliation? | The diffing algorithm that decides which DOM nodes to update, reuse or replace. |
| How do you optimise a slow React app? | Profile first, then code-split routes, memoise hot components, virtualise long lists. |
React Interview Questions for Freshers— Interview Questions & FAQs
What React topics are asked most in fresher interviews?+
Hooks (useState, useEffect and their rules), the virtual DOM and reconciliation, state versus props, keys in lists, controlled components, and basic performance reasoning about re-renders.
Do I need Redux to get a React internship?+
Not usually. A solid grasp of hooks, one real project and a clear explanation of your data flow matter more. Knowing Redux Toolkit or Context is a bonus, not a gate.