Top 10 ReactJS Interview Questions and Answers

ReactJS is a JavaScript library for building user interfaces that have gained immense popularity in recent years. It is used by companies such as Facebook, Netflix, and Airbnb to create interactive and dynamic web applications.

As a ReactJS developer, it’s essential to have a solid understanding of the library’s concepts and features. In this article, we will be discussing the top 10 ReactJS interview questions and answers that will help you prepare for your next interview.

We will also provide tips and strategies on how to prepare for your interview and make sure that you stand out from the competition.

What is ReactJS and its features?
ReactJS is a JavaScript library that allows developers to build reusable UI components. It was first released by Facebook in 2013 and has since become one of the most popular libraries in the web development industry.

ReactJS uses JSX, a syntax extension for JavaScript, which allows developers to write components using a combination of HTML and JavaScript.

The library also utilizes a virtual DOM, which improves the performance of web applications by only updating the necessary components when a change occurs. Additionally, ReactJS has a component-based architecture, which makes it easy for developers to organize and maintain their code.

10 ReactJS Interview Questions:

1. What is JSX?
   JSX is a syntax extension for JavaScript that allows developers to write components using a combination of HTML and JavaScript. It is used in ReactJS to define the structure and content of a component.
2. What is the Virtual DOM?
   The Virtual DOM is a lightweight in-memory representation of the actual DOM (Document Object Model). ReactJS uses the Virtual DOM to improve the performance of web applications by only updating the necessary components when a change occurs.
3. What is the purpose of a component in ReactJS?
   A component in ReactJS is a reusable piece of code that represents a part of a web page. Components can be thought of as small, independent building blocks that make up a larger application.
4. What is the difference between a state and a prop in ReactJS?
   A state is a way of storing data within a component that can change over time, whereas a prop is a way of passing data from a parent component to a child component.
5. What are lifecycle methods in ReactJS?
   Lifecycle methods are methods that get called at specific points during the lifecycle of a component. These methods include componentDidMount, componentDidUpdate, and component will unmount.
6. What is the difference between a controlled and uncontrolled component in ReactJS?
   A controlled component is a component that has its state controlled by the parent component, while an uncontrolled component has its own internal state.
7. What is the purpose of a Higher Order Component (HOC) in ReactJS?
   A Higher Order Component (HOC) is a way of reusing component logic. It is a function that takes in a component and returns a new component with additional functionality.
8. What is the difference between a stateless and stateful component in ReactJS?
   A stateless component is a component that does not have its own state, whereas a stateful component has its own state.
9. What is the difference between a functional and class component in ReactJS?
   A functional component is a component that is defined as a function, whereas a class component is a component that is defined as a class.
10. How does ReactJS handle events?
    ReactJS handles events using synthetic events, which are a cross-browser wrapper around the browser’s native event system. This allows ReactJS to handle events in a consistent manner across different browsers.

How to prepare for a ReactJS Interview:
Review the basics: Brush up on the basics of ReactJS such as JSX, Virtual DOM, components, state, and props. Make sure you have a solid understanding of these concepts before the interview.

1. Practice: Practice answering common interview questions and familiarize yourself with the language and terminology used in ReactJS.
2. Learn about the company: Research the company you are interviewing for and find out if they use ReactJS and if so, for what projects.
3. Understand the project: Understand the project that you are interviewing for, if it’s mentioned in the job listing.
4. Be yourself: Remember to be yourself and let your personality shine through during the interview. Show enthusiasm and a willingness to learn and grow as a developer.

Conclusion:
ReactJS is a powerful library that allows developers to build reusable UI components. In this article, we’ve discussed the top 10 ReactJS interview questions and answers that will help you prepare for your next interview.

We’ve also provided tips and strategies on how to prepare for your interview and make sure that you stand out from the competition. Remember to review the basics, practice, learn about the company, and understand the project.

And most importantly, be yourself and let your personality shine through. Good luck with your interview!