Top 10 most asked React JS Interview Questions and Answers

If you are preparing for a React JS interview, it’s important to familiarize yourself with some of the most commonly asked questions. Below are the top 10 most asked React JS interview questions along with their answers:

1. What is React JS?

   React JS is a JavaScript library for building user interfaces. It allows developers to create reusable UI components and efficiently update the user interface when data changes.

2. What are the key features of React JS?

   Some key features of React JS include virtual DOM, component-based architecture, JSX syntax, and one-way data flow.

3. What is JSX?

   JSX is a syntax extension for JavaScript that allows developers to write HTML-like code within their JavaScript files. It makes it easier to write and maintain the UI code.

4. What is the difference between state and props in React JS?

   State is used for managing component-specific data that may change over time, while props are used for passing data from parent to child components.

5. Explain the concept of virtual DOM in React JS.

   The virtual DOM is a lightweight copy of the actual DOM. When the state of a component changes, React compares the virtual DOM with the actual DOM and only updates the necessary parts to minimize performance impact.

6. What are the lifecycle methods in React JS?

   Some lifecycle methods in React include componentDidMount, componentDidUpdate, and componentWillUnmount. These methods are called at different stages of a component’s life cycle.

7. What is the purpose of key props in React JS?

   The key props are used to uniquely identify elements in a list. They help React identify which items have changed, been added, or been removed.

8. What is the difference between controlled and uncontrolled components in React JS?

   Controlled components are those whose value is controlled by React, while uncontrolled components maintain their own state. Controlled components are typically preferred for better control and performance.

9. Explain the concept of higher-order components in React JS.

   Higher-order components are a pattern used in React for reusing component logic. They are functions that take a component and return a new component with additional functionality.

10. What are the advantages of using React JS?

    Some advantages of using React JS include easier creation of dynamic user interfaces, improved performance with virtual DOM, and strong community support with a wide range of libraries and tools.