React Interview Q&A 2025 is your go-to resource for preparation. If you dream of becoming a React developer in 2025, you are at the right address.
React is still one of the most loved JavaScript libraries and is used by everything from social-media applications to SaaS dashboards.
To help you score high on your next React interview, we have compiled a list of 30 of the most common questions along with simple and lucid answers.
So if you are a newcomer or just brushing up on your interview skills before changing jobs, this is your collection.

1. What is React?

React, the JavaScript library mainly used for building user interfaces concerning their applications TP applications are dynamic in the creation of reusable UI components, which makes it faster and easier in development in its creation by Facebook.

2. What are React Components in React Interview Q&A 2025?

Components are the fundamental blocks of any React application and can be functional or class-based, depending on the occasion.

They help break the UI into reusable pieces so that you do not repeat yourself again and again while building features.

3. What is JSX in React Interview Q&A 2025?

JSX, which stands for JavaScript XML, lets you use write HTML in JavaScript, which makes your code more readable and easier to debug.

It looks strange at first, but over time becomes second nature given an understanding of how it bridges markup and logic in React apps.

4. What is the virtual DOM?

The virtual DOM is a lightweight copy of the actual DOM. React uses it to make UI updates faster and efficient.

React compares both the virtual and real DOM and updates only what’s changed, saving time and performance.

5. What’s the difference between state and props?

Props are read-only and passed from parent to child while the state is local and mutable. The props are taken to customize components, while the state is internal data like user input or toggles.

6. What are functional components?

A functional component is an ordinary JavaScript function which yields JSX and is not having its own lifecycle methods.

It is simple to use for simple fragments of user interface and is widely used nowadays as React Hooks are getting popular.

7. What are React Hooks?

React Hooks allow you to have state and other React features in functional components without needing to write a class.

Most popular hooks are useState and useEffect – you will be always using them in real-world projects.

8. What does useState do?

useState is a React Hook. It allows you to easily add local state to functional components with just a few lines of code.

You call it with an initial value and it returns back the current state and a function to update it.

9. For what made useEffect?

The useEffect function allows you to do side effects in your functional components such as fetching data and setting up event listeners.

This is quite similar to the lifecycle methods componentDidMount and componentDidUpdate in class components.

10. How to Handle Events in React?

React events are handled just like pure plain JavaScript events but with some modifications as eg – camelCase in the place of lowercase event names.

They also take functions as event handlers which keeps your code neat and modular.

11. What is a key in React lists?

Every item in a list must possess a key index which identifies them while using React that tracks the changed or removed items.

React might use the wrong elements while rendering lists. It builds wreckage in its mind if there are no keys.

12. What are Refs in React?

Refs will allow us to directly access any DOM nodes or React elements without the involvement of the basic data flow. Refs help for focusing inputs, for scrolling elements, or to use with third-party libraries.

13. What is Prop Drilling?

Prop drilling is passing props through many layers of nested components only to reach a child component that is much further and deeper into the trees.

The whole process can be quite messy sometimes, but props passing is avoided globally using API like Context.

14. What is Context API?

Context API is the part of React that is used for sharing like theme or user information between components from prop drilling.

It’s a much more manageable way to declare states, especially in tons of components in huge applications.

15. What are controlled components?

Controlled components are form components such as input or textarea that get their values controlled by React state. This gives much better scope for form validation, formatting, and behavior.

16. What are Uncontrolled Components?

Uncontrolled components hold their own state within themselves and to access the values, you use refs when required. Quick and simple to begin with but hard to control and difficult to validate.

17. What is Lifting State Up?

Lifting state up can be described as the movement of common state to the nearest common ancestor for component sharing (‘sharing’ in the sense of access to and modification of that data).

This increases the effectiveness of the communication between sibling components.

18. What is the difference in definitions between useEffect and useLayoutEffect?

useEffect runs on the cease of DOM updates even as useLayoutEffect runs just earlier than the browser paints the modifications.

you could invoke useLayoutEffect best when you want to measure format change without delay after rendering.

19. What are excessive-Order additives (HOC)?

A better-order factor is a characteristic that takes a component as argument and returns a new aspect with additional features or facts.
A HOC just wraps the component in order that it receives more advantageous without tampering with its number one good judgment.

20. What is the useMemo redux hook?

useMemo is useful where you want to optimize performance by using memoizing luxurious calculations in order that they will no longer be carried out once more except wanted.

This is specifically useful to avoid inflicting needless re-renders.

21. What is the useCallback function in the React library?

useCallback returns the memoized model of a specific feature in order that it must not be created each time your issue re-renders.

This is awesome for optimizing overall performance even as passing features to infant additives.

22. What is React Router?

React Router helps you to effortlessly upload navigation and routing on your React programs. In quick, it allows you build single-page programs that may have more than one pages or views using URLs.

23. What is lazy loading in React?

Lazy loading means loading those components or assets when they are really required for better performance and higher speed.
This lazy loading is supported in React through React.lazy and Suspense.

24. What is Suspense in React?

Suspense lets you wait for some resource—such as lazy-load components—before there’s rendering on the screen.
While the component is being fetched, show a loading spinner or message.

25. What is error boundary in React?

An error boundary is a component that catches JavaScript errors made by its children, and instead of crashing the entire application, it shows a fallback UI.
They are useful to make your application more friendly and stable in case of unforeseen problems.

26. What is reconciliation in React?

Reconciliation is the process React uses to understand which things need to be changed in the DOM.
This is done through comparing elements that are different from to the new one and updating only the changes thus making it more efficient.

27. What is the difference between class and functional components?

Class components are an ES6 class with lifecycle methods, whereas functional ones are simpler, with hooks.
Functional Components have become very commonplace now and are recommended with most usage as well.

28. What is Redux?

Redux is yet another third-party library for state management in which we can manage the global state in a predictable way throughout the application.

It can also be used with React, especially in large-scale applications that need centralized data handling.

29. What is the difference between Redux and Context API?

Redux comes with various middlewares and dev tools capabilities; Context API is a simple API for small apps that is built-in to React.

Choose Redux for complex logic and Context for lightweight state propagation.

30. What are some best practices to prepare for a React interview?

Practice building applications, familiarize oneself with hooks and lifecycle methods, and keep abreast of the latest updates and patterns in React.

Mock interviews, reading blogs, and doing some coding will also help raise your confidence and help you to be more prepared.

For a comprehensive list of common questions, check out this helpful ReactJS interview questions repository.

Final Thoughts Preparing Up for a React Interview

It may sound like an overwhelming job placing oneself to go through an interview in React; this can be easier if approached right, with practice and good guidance.

Studying React Interview Q&A 2025 resources can help simplify your preparation by highlighting the most relevant topics.

It is all about breaking things into smaller pieces, practicing every day, and keeping curious about how things get done under the hood.

You do not have to memorize; you should grasp the concept and know where and when to use it.
You can build a mini-project or while explaining concepts to anyone, and it may help you get out of the stuck situations.

Think components, hooks, and clear logic-the rest will follow. You’ll know that you’re good when you get there. So dive into React Interview Q&A 2025, keep at it, and you’ll gain the confidence to succeed.