React JS Interview Questions India 2025

If you are a frontend developer in India eyeing a role at TCS, Infosys, Flipkart, or a high-growth startup in 2025, mastering React JS interview questions is no longer optional — it is the single most important thing standing between you and your dream offer letter.

Why React JS Is Dominating the Indian Job Market in 2025

The Indian IT landscape has undergone a seismic shift over the last three years. Digital transformation projects at banks, e-commerce giants, and SaaS companies have exploded demand for skilled React developers. According to data from Naukri.com and LinkedIn India, job postings requiring React JS expertise grew by over 60% between 2022 and 2024, and that trajectory is continuing into 2025.

Companies like Wipro Digital, Cognizant's digital practice, Razorpay, Meesho, Zepto, and PhonePe are actively hiring React engineers at every level — from freshers out of engineering colleges to senior architects with eight-plus years of experience. Even traditional IT services giants like TCS and Infosys have reoriented their frontend teams around React, replacing legacy Angular and jQuery codebases.

What does this mean for you? Competition is fierce, but so is opportunity. The candidates who crack these interviews are not necessarily the ones who have memorised the React documentation — they are the ones who can explain concepts clearly, connect them to real-world problems, and demonstrate hands-on experience. This guide is designed to help you become exactly that kind of candidate.

How Indian Companies Structure React JS Interviews

Before diving into the questions themselves, it helps to understand how top Indian employers actually run their React interview processes. The structure varies by company type, but here is the most common pattern you will encounter:

• Round 1 — Online Assessment: Companies like TCS iON and Wipro WILP use timed MCQs covering JavaScript fundamentals, React basics, and sometimes CSS. Platforms like HackerEarth and HackerRank are frequently used.
• Round 2 — Technical Phone or Video Screen: A 45-to-60-minute conversation with a senior developer or tech lead. Expect conceptual questions and one or two live coding problems.
• Round 3 — Deep Technical Interview: This is where system design, advanced React patterns, and project-based discussions happen. Startups like Razorpay and Swiggy are known for rigorous rounds here.
• Round 4 — Managerial or HR Round: Behavioural questions, salary negotiation, and cultural fit assessment.

Product companies like Flipkart and Zomato often add a dedicated system design round where you are expected to architect a frontend system at scale — think designing a cart system or a real-time order tracking dashboard using React.

Core React JS Interview Questions for Freshers

If you are appearing for your first or second job interview and targeting companies like Cognizant, Capgemini, or mid-size Indian product startups, these foundational questions will form the backbone of your preparation.

1. What is React and what problem does it solve?

Interviewers at Infosys BPM and Accenture India love starting with this deceptively simple question. Your answer should go beyond "it's a JavaScript library." Explain that React solves the problem of efficiently updating and rendering UI components when data changes, using its virtual DOM to minimise expensive real DOM manipulations. Mention that it was created by Facebook and is maintained by Meta, which gives it long-term stability — a point that resonates with enterprise-focused interviewers.

2. Explain JSX and why it is used.

JSX (JavaScript XML) is a syntax extension that allows you to write HTML-like code inside JavaScript files. It makes the component structure more readable and intuitive. A common follow-up question in Indian interviews is whether JSX is mandatory — the answer is no, but it is universally preferred because the alternative (using React.createElement() directly) is verbose and hard to read at scale.

3. What is the difference between state and props?

This is asked in virtually every fresher-level React interview in India. The clean way to answer it:

• Props are read-only inputs passed from a parent component to a child component. They cannot be modified by the receiving component.
• State is mutable data managed within a component itself. When state changes, React re-renders the component.

A practical example you can give: in a Flipkart-style product listing page, the product data passed from a parent container to a product card component would be props, while the wishlist toggle (on/off) inside the card would be local state.

4. What are functional components and class components?

As of 2025, functional components with hooks are the industry standard. However, many legacy codebases at TCS and Wipro still contain class components, so you need to understand both. Functional components are simpler, easier to test, and perform better. Class components use lifecycle methods like componentDidMount and componentDidUpdate, which are now largely replaced by the useEffect hook.

5. What is the virtual DOM and how does it work?

The virtual DOM is a lightweight in-memory representation of the actual DOM. When your application's state changes, React first updates the virtual DOM, then uses a diffing algorithm to compare it with the previous virtual DOM snapshot, and finally applies only the necessary changes to the real DOM. This process, called reconciliation, is what makes React fast and is a frequent topic in both fresher and experienced React JS interview questions India 2025 rounds.

Advanced React JS Interview Questions for Experienced Professionals

If you are a mid-level or senior developer targeting roles at companies like PhonePe, Swiggy, CRED, or MNC product divisions, the following questions represent what you should be deeply comfortable with.

6. Explain all major React Hooks with use cases.

React hooks interview questions are a massive category in themselves. Here are the hooks you must know cold:

• useState: Manages local component state. Example — controlling form input values.
• useEffect: Handles side effects like API calls, subscriptions, and DOM manipulations. It replaces componentDidMount, componentDidUpdate, and componentWillUnmount.
• useContext: Consumes a React context without prop drilling. Widely used for theme management and auth state.
• useReducer: An alternative to useState for complex state logic. Think of it as a mini Redux inside a component.
• useMemo: Memoises expensive computed values to prevent unnecessary recalculations on re-renders.
• useCallback: Memoises callback functions so they are not recreated on every render, useful when passing callbacks to child components.
• useRef: Holds a mutable reference that persists across renders without triggering re-renders. Used for accessing DOM elements directly.
• useLayoutEffect: Similar to useEffect but fires synchronously after DOM mutations — important for measuring DOM elements.

7. What is React Context API and when should you use it over Redux?

The Context API is React's built-in solution for sharing data across the component tree without prop drilling. It is ideal for low-frequency updates like user authentication status, theme preferences, and language settings. Redux (or Redux Toolkit) is more appropriate when you have complex, high-frequency state updates across many parts of your application — like a shopping cart in a Meesho-style e-commerce app where cart state affects dozens of unrelated components.

A nuanced answer here will impress senior interviewers: mention that using Context for high-frequency updates can cause performance issues because every component consuming the context will re-render when any value in the context changes.

8. How does React handle performance optimisation?

This is one of the most popular senior React developer interview questions in India. A strong answer covers multiple layers:

1. React.memo: Wraps a functional component to prevent re-rendering if props have not changed.
2. useMemo and useCallback: Prevent expensive recalculations and function recreation.
3. Code splitting with React.lazy and Suspense: Loads components only when they are needed, reducing initial bundle size. Critical for apps like Nykaa or BigBasket where time-to-interactive matters.
4. Virtualisation: Libraries like react-window or react-virtual render only the visible portion of long lists — essential for infinite scroll feeds.
5. Avoiding anonymous functions in JSX: Every render creates a new function reference, which can break memoisation.

9. Explain the React component lifecycle.

Even though class components are less common today, lifecycle knowledge is tested regularly at Cognizant and Wipro because their legacy projects still rely on them. The three main phases are:

• Mounting: constructor → render → componentDidMount
• Updating: shouldComponentUpdate → render → componentDidUpdate
• Unmounting: componentWillUnmount

For functional components, map these to useEffect: an empty dependency array mimics componentDidMount, a return function inside useEffect mimics componentWillUnmount, and a dependency array with values mimics componentDidUpdate.

10. What is server-side rendering (SSR) and how does Next.js relate to React?

In 2025, Next.js is frequently mentioned in React job descriptions across India — especially at companies building SEO-sensitive applications like news portals, edtech platforms (Unacademy, BYJU's rebuilds), and e-commerce sites. SSR renders React components on the server and sends fully formed HTML to the browser, which improves initial load time and SEO. Next.js provides SSR, static site generation (SSG), and incremental static regeneration (ISR) out of the box, making it a natural extension of React knowledge that interviewers increasingly expect.

11. What are Higher-Order Components (HOCs) and custom hooks?

Higher-Order Components are functions that take a component and return a new enhanced component. They are a pattern for reusing component logic — for example, wrapping components with authentication checks. Custom hooks are the modern, preferred alternative. A custom hook is a JavaScript function whose name starts with "use" and that can call other hooks. For example, a useFetch hook that abstracts API calling logic can be reused across dozens of components — a real-world pattern seen in Razorpay's and Groww's frontend codebases.

React JS Coding Questions Asked in Indian Interviews

Technical rounds at product companies almost always include live coding. Here are the most frequently assigned problems in React JS interview rounds across India in 2025:

• Build a counter component with increment, decrement, and reset functionality using useState.
• Implement a search filter that filters a list of items as the user types, using controlled inputs and useMemo for optimisation.
• Create a custom useFetch hook that handles loading, error, and data states for any API endpoint.
• Build a to-do list application with add, delete, and toggle-complete functionality — a classic that tests your understanding of state management and component structure.
• Implement infinite scroll using useEffect and the Intersection Observer API.
• Create a form with validation using controlled components and display real-time error messages.

Pro tip from Indian hiring managers: Candidates who explain their thought process out loud while coding — talking through their state structure, component hierarchy, and potential edge cases — consistently get rated higher than silent coders, even if the final code has minor bugs.

React JS System Design Questions for Senior Roles

For senior React developer roles at companies like Flipkart, Razorpay, or Dunzo, you will likely face at least one system design or architecture question. These are increasingly common in JavaScript framework interview questions India rounds for senior positions.

• Design the frontend architecture for a real-time stock trading dashboard — this tests your knowledge of WebSockets, state management, and performance optimisation.
• How would you structure a micro-frontend architecture for a large e-commerce platform where different teams own different sections?
• Design a reusable component library for a fintech company — how would you ensure accessibility, theming, and bundle size efficiency?
• How would you implement authentication and route protection in a large React application using React Router v6?

Common Mistakes Indian Candidates Make in React Interviews

Having coached hundreds of developers preparing for frontend developer interview India roles, here are the mistakes that cost candidates offers most often:

• Memorising answers without understanding: Interviewers probe with follow-up questions. If you cannot extend your answer, it is obvious you memorised it.
• Ignoring JavaScript fundamentals: React is built on JavaScript. Weak closures, prototype, and async/await knowledge will sink you even if you know React well.
• Not practising on a whiteboard or blank editor: Most coding rounds use CodePen, CodeSandbox, or a shared Google Doc — not your IDE with autocomplete.
• Underestimating CSS: Many Indian React interviews include at least one layout question — Flexbox, Grid, or responsive design. Do not neglect it.
• Failing to mention testing: Companies like PhonePe and Cleartax ask about React Testing Library and Jest. If you have never written a test, start now.

How to Prepare Your React JS Resume for ATS Systems

Before you even get to the interview, your resume must clear the Applicant Tracking System (ATS) filters used by HR teams at TCS, Infosys, and most product companies. Use the exact keywords from the job description — terms like "React.js," "React Hooks," "Redux Toolkit," "Next.js," "REST APIs," and "unit testing" must appear in your skills and experience sections. Quantify your achievements wherever possible: "reduced page load time by 40% through code splitting" is infinitely more compelling than "worked on performance optimisation."

Build your free ATS resume tailored for React JS roles in India and make sure your application reaches the hiring manager's desk.

Recommended Resources for React JS Interview Preparation in 2025

Structured preparation beats random YouTube browsing. Here is a focused resource plan:

1. Official React Documentation (react.dev): The newly redesigned docs are excellent and include interactive examples. Read the "Learn React" section end-to-end.
2. JavaScript.info: Strengthen your JavaScript foundation — closures, promises, async/await, and the event loop are tested everywhere.
3. Frontend Masters and Scrimba: Paid courses but worth it for structured, project-based learning.
4. LeetCode and HackerRank: Solve at least 50 medium-difficulty JavaScript and data structure problems before appearing for product company rounds.
5. GitHub: Build two or three real projects — a weather app using a public API, a budget tracker with local storage, or a movie search app — and push them to GitHub. Interviewers at Indian startups often ask for GitHub links.

Salary Expectations for React Developers in India in 2025

Understanding the market helps you negotiate confidently. Based on current data from AmbitionBox and LinkedIn Salary India:

• Fresher / 0–2 years: ₹4–8 LPA at service companies; ₹8–15 LPA at product startups in Bengaluru, Hyderabad, and Pune.
• Mid-level / 2–5 years: ₹12–22 LPA at companies like Infosys, Wipro; ₹18–35 LPA at companies like Razorpay, CRED, Groww.
• Senior / 5+ years: ₹25–50+ LPA, especially if you have system design experience and have worked on products at scale.

Remote work has also blurred these bands — Indian developers working for US-based companies through platforms like Toptal or directly employed remotely can earn 2–3x these figures.

Conclusion

The demand for skilled React developers in India in 2025 is at an all-time high, and so is the competition. Whether you are a fresher aiming for your first role at a service company or an experienced engineer targeting a product startup, success in your React JS interview comes down to three things: conceptual depth, practical coding ability, and clear communication. Use this guide to identify your weak areas, build projects that demonstrate real-world skills, and walk into every interview ready to connect theory to practice. The roles are out there — companies like Razorpay, PhonePe, Flipkart, and hundreds of funded startups are actively hiring right now. Your next career move starts with preparation, and preparation starts today.