Top 100 React Interview Questions and Answer

React aka ReactJS or React.js is an open-source JavaScript library, developed by Facebook. 

Advantages of ReactJS

– Simplifies the process of writing component – Improves productivity and makes maintenance smoother – Delivers an excellent solution for high-load application – Ensures stable code

What is a virtual DOM?

Virtual DOM is more like making changes in software code than in the actual hardware. It is faster than DOM as it can be manipulated easily.

Why can’t browsers read JSX?

React uses JSX (JavaScript Extension) that allows us to replicate HTML in JavaScript. Since JSX is not valid JavaScript, web browsers can’t read it directly. 

What is the purpose of render() in React?

The render() function must return something, be it null. The component file is called the render() method by default .

What are the Pure components in ReactJS?

The pure component helps to use the lifecycle method for comparing the states or props for any changes in the properties before re-rendering the component.

What is Redux?

It is a predictable state container for JS Apps.  Redux is a small open-source JavaScript library for managing application states.