React Interview Questions

React is a declarative, component-based JavaScript library developed by Facebook for building fast, scalable, and modular user interfaces.

Its key features include one-way data binding, virtual DOM diffing, reusable components, and support for both client-side and server-side rendering (SSR).

React encourages a unidirectional data flow, making application state predictable and debugging easier.

It integrates well with tools like Redux, React Router, and Next.js for enhanced functionality.

React’s popularity stems from its simplicity, flexibility, and strong ecosystem, making it suitable for everything from small widgets to enterprise-grade applications.

Components are the fundamental building blocks of React applications, designed to encapsulate UI logic and appearance.

There are two primary types: functional components (simple functions returning JSX) and class components (ES6 classes extending React.Component with lifecycle methods).

Functional components with hooks (like useState, useEffect) have become the preferred approach since React 16.8.

Components promote modularity, reusability, and separation of concerns in large-scale applications.

Well-designed components are self-contained, testable, and easy to compose, leading to faster development cycles and more maintainable codebases.

JSX stands for JavaScript XML and is a syntax extension that allows developers to write HTML-like structures directly in JavaScript code.

It simplifies the creation of complex UIs by combining markup and logic in a single file, enhancing readability and developer experience.

Under the hood, JSX is transformed into standard React.createElement() calls during the build process using Babel or similar tools.

While optional, JSX is heavily encouraged in React development due to its clarity and expressiveness.

JSX enables developers to think in terms of UI components rather than imperative DOM manipulations, aligning closely with React’s declarative nature.