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Introduction to ReactJS: Learn Components, Usage, and Features

Hitesh Umaletiya
Hitesh Umaletiya
April 8, 2024
Clock icon5 mins read
Calendar iconLast updated April 25, 2024
introduction to ReactJS
Quick Summary:- Learn what role ReactJS plays in web development today. This blog serves as an introduction to ReactJS for beginners.

Introduction to ReactJS

Have you ever wondered what's common among Netflix, Reddit, Airbnb, Uber Eats, and Facebook? Aside from being widely used and immensely popular, they all share a technological backbone: ReactJS.

ReactJS, a JavaScript library that was initially developed by Facebook for its internal use, has now become a staple in the tech industry. It is widely adopted, from startups to big companies, and is used by over 40% of web developers worldwide. In fact, it was the second most used web framework among developers worldwide in 2023.

ReactJS is used in a wide range of applications. Some notable examples include Netflix's movie recommendation system, Airbnb's search and booking system, and Uber Eats' food delivery tracking system. These applications demonstrate the versatility and power of ReactJS in developing complex, interactive, and user-friendly web applications.

ReactJS is primarily used to develop complex web applications. If you need to become more familiar with It, this article will serve as an introduction. Additionally, we'll explore its applications, features, and a ReactJS component to provide insight into its role in web development.

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Role of ReactJS in Web Development World

Before we understand ReactJS's role in modern web development, let's first briefly understand the broader picture of web development.

Let's break it down in plain English.

When we say web application development, we may refer to both the front and back end. The front end is the part of the website that users interact with, while the back end handles the logic and data processing. Several technologies exist today to power both ends of this spectrum.

React.js is used in front-end (client-side) development, specifically for a website's user interfaces. A popular example of ReactJS development is Facebook's web app, which uses it to power several elements.

You might have observed the functionality of Facebook's web app, where tapping on elements doesn't trigger a complete page reload. Instead, React.js efficiently updates the state of specific elements behind the scenes.

ReactJS is used to develop dynamic web pages, which are web pages that can update their content or appearance in response to user actions or changes in data. These pages offer users a smoother experience compared to traditional pages that reload entirely with each interaction. ReactJS is particularly well-suited for developing dynamic web pages, including single-page applications, mobile apps (with React Native), complex user interfaces, real-time applications, and more.

If you are still trying to figure out after exploring the ReactJS features, don't worry. We'll also explore various use cases of ReactJS to help you understand when it's an ideal choice and the types of applications you can develop with it.

What is ReactJS?

React.js, often referred to simply as React, is an open-source JavaScript library for building user interfaces. Its user-friendly nature allows for faster creation of web UIs, making it a go-to choice for world-renowned brands, including Netflix, Salesforce, Instagram, Reddit, and countless organizations. With React, building interactive web pages becomes a breeze. 

As per the Stack Overflow 2023 Developer Survey, it is one of the most popular web frameworks. 

Features of ReactJS

It follows a component-based architecture, a widely adopted approach for building modern applications. Since modern applications require continuous upgrading, its component-based nature allows developers to add new functionalities without rewriting the entire application.

Additionally, it provides an exclusive JSX language that promotes code maintainability and helps write components more efficiently. Other key features of ReactJS include its ability to handle complex UI updates, its support for server-side rendering, and its robust community and ecosystem. Let's look at some key features of ReactJS that every developer should know. 

1. JSX

JSX (JavaScript XML) is a JavaScript extension that allows you to write HTML-like code directly within your React components. It's a powerful tool that enables you to keep your UI logic and data handling together in a single place, enhancing code maintainability. While React allows you to write UI code without JSX, using JSX can make your code more readable and promote a more organized and maintainable codebase, making it a popular choice among React developers. 

While React allows you to write UI code without JSX, you will find JSX to be a helpful tool as it allows you to write the logic more readably and promotes a more organized and maintainable codebase.

2. Virtual DOM

DOM (Document Object Model) plays a crucial role in web application rendering. However, React takes a different approach by utilizing a Virtual DOM.

React takes a unique approach to web application rendering by utilizing a Virtual DOM. In simple terms, the Virtual DOM is a lightweight copy of the actual DOM, which is the structure of a web page. React creates and maintains this virtual copy, allowing it to efficiently update only the necessary parts of the page when the application's state changes. This approach minimizes browser work and improves rendering speed, contributing to React's exceptional performance and responsiveness. 

This creates a virtual copy because when your application state changes, React updates the virtual DOM first. It then compares the virtual DOM with the real DOM to identify the minimal changes necessary. Only the essential changes are applied to the actual DOM, minimizing browser work and improving rendering speed.

React achieves lightning-fast rendering without directly manipulating the entire DOM, avoiding resource-intensive operations. This optimization is a major reason React applications are renowned for their exceptional performance and responsiveness. With React, you can be confident in the efficiency and speed of your web applications.

3. Component-Based Architecture

React apps are built using reusable components. Each component represents a distinct UI part and encapsulates its logic and representation. This component-based architecture makes building and maintaining complex UIs easier, as each component can be developed and tested independently. It also promotes code reusability, as components can be used in multiple parts of an application.

This approach is widely popular in the modern development. It lets you construct your UI by breaking it down into reusable, independent components. 

With JSX, you can efficiently construct components and create applications at a rapid pace. This is why it is recommended that you write code in JSX in React to build complex UI and develop reusable components efficiently. 

4. Unidirectional Data Flow

In React, the data flows in a single direction, from top to bottom, i.e., from parent to child components through properties. This unidirectional data flow is a key concept in ReactJS. It simplifies reasoning about how changes in data will affect the UI and prevents unintended side effects. This makes it easier to understand and debug React applications, and also contributes to the development of maintainable applications. 

This predictable data flow simplifies reasoning about how changes in data will affect the UI and prevent unintended side effects. Furthermore, this unidirectional data flow is advantageous for developing maintainable applications. 

5. Components 

React components are independent and reusable building blocks that define a part of a user interface. In React, components can represent any part of your application's UI or functionality. They can range from simple elements like buttons or colors to more complex components like forms, modals, navigation bars, and entire sections of your application.

6. React Hooks

In React, there are two types of components: Functional components and class components. Functional components enable writing code more straightforwardly and concisely. React Hooks, introduced in React 16.8, further enhance the functionality of functional components. They allow developers to manage state and perform side effects within them, making it easier to reuse stateful logic between components.

Side effects are actions that occur outside the component's render function, such as data fetching, subscriptions, or manually changing the DOM.

By utilizing Hooks, developers can achieve the functionality traditionally associated with class components within functional components. We will delve deeper into functional components and class components later in this article.

7. State

State in React is the internal data of a component. It encapsulates information that can change over time, influencing the component's behavior and appearance. State is commonly used to handle dynamic data such as user input, toggling UI elements, or managing component lifecycle events. 

It is mutable, meaning it can be modified, triggering re-renders of the component to reflect the updated state.

8. Props

Props, short for properties, are immutable data passed from a parent component to a child component. They serve as a means of communication between components, allowing data to be passed down the component tree. This makes it easier to manage and update data in React applications. 

Props facilitate the creation of flexible and modular components. They are commonly used to configure child components, pass event handlers, or provide contextual information. Functional components, especially with the widespread adoption of React Hooks, heavily rely on props to receive data and trigger actions within the component.

Components Of ReactJS

Components in React are independent and reusable pieces that encapsulate UI(user interface) logic and data. 

There are two main types of React components:

Class components

These are traditional JavaScript classes that extend the `React.Component` class. Class components have a render method that returns the UI for the component, as well as a number of lifecycle methods that allow you to hook into different stages of the component's lifecycle (e.g., when the component is mounted, updated, or unmounted).

Functional components 

These are simply JavaScript functions that return JSX (JavaScript XML) code that describes the UI for the component. Function components are generally simpler to write and use than class components, and they are the preferred way to write React components in modern React applications.

Components can also be nested within other components, which allows you to build complex UIs by composing smaller, reusable components. This hierarchical structure makes it easy to break down complex UIs into manageable pieces.

Use of ReactJS

Here are some of the common uses of ReactJS:

1. Building Single-Page Applications (SPAs)

ReactJS is a popular choice for building SPAs because it allows you to create dynamic and responsive UIs that update without reloading the entire page, providing a smoother user experience.

2. Creating Reusable UI Components

A core strength of ReactJS is its emphasis on reusability. Developers can avoid code duplication and speed up the development process by building components that encapsulate both UI and logic.

3. Developing Complex User Interfaces

React's component-based architecture makes it well-suited for building complex UIs with a lot of interactivity. Components can be nested to create hierarchical structures, and state management solutions like Redux can help manage complex application state.

4. SEO Optimization

React applications can be SEO-friendly by using techniques like server-side rendering (SSR) or static site generation (SSG). This ensures that search engines can properly crawl and index your content.

5. Mobile App Development (with React Native)

React Native is a framework that allows you to use React skills to build native mobile apps for iOS and Android. This can save development time and resources if you need to create a mobile app alongside your web application.

Facebook, Instagram, Netflix, and Dropbox are real-world examples of ReactJS applications. 


ReactJS is a versatile JavaScript library that can be used to build a wide variety of web applications. Its focus on reusability, performance, and developer experience has made it one of the most popular choices for front-end development today. With our React Development Services, you can create your ideal team seamlessly. Whether you're looking to strengthen your current team or establish a proficient one from scratch, we're here to realize your app vision.

Hitesh Umaletiya

Hitesh Umaletiya

Co-founder of Brilworks. As technology futurists, we love helping startups turn their ideas into reality. Our expertise spans startups to SMEs, and we're dedicated to their success.

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