ReactJS – Introduction

ReactJS is a popular JavaScript library developed by Facebook for building user interfaces (UIs), especially for single-page applications where dynamic and responsive experiences are required. It follows the component-based architecture and uses a declarative programming approach, making it efficient and easier to reason about.

ReactJS is a free and open-source front-end JavaScript library which is used to develop various interactive user-interfaces. It is a simple, feature rich and component based UI library. When we say component based, we mean that React develops applications by creating various reusable and independent codes. This UI library is, thus, widely used in web development.

ReactJS can be used to develop small applications as well as big, complex applications. ReactJS provides minimal and solid feature set to kick-start a web application.

Key Features of ReactJS :

Component-Based Architecture : Applications are built using reusable and encapsulated components. Each component manages its own state and can be combined to create complex UIs.

Declarative UI : React allows developers to describe what the UI should look like. React takes care of updating and rendering the UI efficiently when the data changes.

Virtual DOM : React uses a lightweight representation of the DOM called the Virtual DOM. Changes to the UI are first made to the Virtual DOM, and then React calculates the minimal updates needed in the real DOM, optimizing performance.

Unidirectional Data Flow : Data flows in a single direction, from parent components to child components. This makes it easier to understand and debug applications.

JSX (JavaScript XML) : React uses JSX, which is a syntax extension allowing HTML-like code within JavaScript. JSX improves readability and integrates well with JavaScript code.

React Hooks : Introduced in React 16.8, hooks like useState, useEffect, and others allow developers to use state and lifecycle methods in functional components.

React Router : A library for routing in React applications, enabling navigation between different views or pages.

Benefits of ReactJS:

Fast Performance : Virtual DOM and efficient diffing algorithms minimize direct manipulation of the DOM.

Reusable Components : Enhances development speed and maintainability.

Strong Community and Ecosystem : React has a large developer community, extensive libraries, and third-party tools.

SEO-Friendly : Server-side rendering with frameworks like Next.js enhances search engine optimization.

Cross-Platform Development : With React Native, developers can build mobile applications using the same principles.

Applications

Few popular websites powered by React library are listed as follows

Facebook, popular social media application : React was originally developed at Facebook (or Meta), so its only natural that they use it to run their application. As for their mobile application, it uses React Native to display Android and iOS components, instead of DOM. Facebook’s codebase now includes over 20,000 components and uses the React version that is public.

Netflix, popular media streaming application : Netflix switched to React in 2015. The factors that mainly influenced this decision are the 1) startup speed to reduce the processing time to render the homepage and enabling dynamic elements in the UI, 2) modularity to allow various features that must coexist with the control experience and 3) runtime performance for efficient UI rendering.

Code Academy, popular online training application : Code Academy uses React as the “script is battle-tested, easy to think about, makes SEO easy and is compatible with legacy code and flexible enough for the future”.

Reddit, popular content sharing application : Reddit is also developed using React from the scratch

Instagram, popular photo sharing application : Instagram is also completely based on React, as it is powered by Meta as well. The main features to show its usage include Geo-locations, Hashtags, Google Maps APIs etc.