Most React js Interview Questions and Answers – Part 1

If you are preparing for a React js interview, you may encounter a wide range of questions related to the popular JavaScript library. Whether you are a beginner or an experienced developer, it’s important to be well-prepared for the interview. Below are some common React js interview questions and their answers to help you get ready.

Question 1: What is React js?

Answer: React js is a JavaScript library for building user interfaces. It allows developers to create interactive UIs using a component-based architecture. React js is developed and maintained by Facebook and a community of individual developers and companies.

Question 2: What are the key features of React js?

Answer: Some key features of React js include its component-based architecture, virtual DOM, JSX syntax for writing HTML in JavaScript, and its focus on reusability and declarative programming.

Question 3: What is the difference between functional components and class components in React?

Answer: Functional components are defined as JavaScript functions and are simpler and easier to read compared to class components. Class components, on the other hand, are defined using ES6 classes and have access to additional features such as state and lifecycle methods.

Question 4: What is JSX?

Answer: JSX is a syntax extension for JavaScript that allows developers to write HTML directly within JavaScript code. It makes it easier to write and understand React components by combining HTML and JavaScript into a single file.

Question 5: What is the virtual DOM in React js?

Answer: The virtual DOM is a lightweight copy of the actual DOM in memory. React uses the virtual DOM to efficiently update the actual DOM when there are changes, which helps improve performance and speed up rendering.

These are just a few examples of the types of questions you may encounter in a React js interview. It’s important to study and understand the core concepts of React js, as well as practice coding and problem-solving with the library. Good luck!