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Last Updated: Oct 30, 2023

ReactJS Tutorial

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ReactJS is an efficient, flexible and declarative Javascript library to build user interfaces. In the current era ReactJS is one of the most popular JavaScript front-end libraries which has a strong foundation and a large community support.

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In this blog, we'll be diving deep into the world of React JS, exploring its features, advantages, disadvantages, and use cases. We will be covering all the major aspects of this technology. So if you're ready to take your web development skills to the next level, let's dive into the blog.

Also See, Hooks in React JS

What is React JS?

React, or React JS, is a popular open-source JavaScript library used for building UI. It is designed to make it easier to build reusable UI components that can be used throughout the application. The core idea behind React is to break down a UI into smaller, reusable components, each manages its own state and can be composed together to build more complex UIs. React uses a virtual DOM (Document Object Model) to efficiently update the UI in response to changes in the application state without having to redraw the entire page.

React JS also supports a declarative programming style, which means that developers can describe the desired UI in terms of its structure and behaviour rather than specifying the exact sequence of steps to build it. React JS has become popular in web development due to its flexibility, modularity, and performance benefits. It is widely used by companies such as Facebook, Instagram, Airbnb, and Netflix to build complex, high-performance UI. 

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Why do we use ReactJS?

ReactJS is a popular open-source JavaScript library used for building user interfaces. It is popular in web development for several reasons. The following are some reasons why we use ReactJS:

  1. ReactJS follows a component-based approach, dividing the user interface into reusable components. The structure makes managing and maintaining complex applications more effortless.
  2. ReactJS implements a virtual Document Object Model (DOM) that acts as an abstraction layer between the HTML DOM and the application. When we change the application's state, React updates the virtual DOM and determines the minimal changes in the actual DOM. This approach helps us to improve performance and speed.
  3. React allows developers to create reusable UI components. This reusability leads to faster development, easier maintenance, and consistent user experiences. We can build more complex interfaces using these components, providing flexibility and scalability.
  4. React follows a unidirectional data flow known as one-way binding. This means that data in a React application flows in a single direction, from parent to child components. This approach makes it easier to track and understand how data changes over time, eliminating the possibility of data inconsistencies and unexpected mutations.
  5. React has various libraries, tools, and extensions that enhance its capabilities. It has a large and active community; developers contribute and find support and resources.


These are the prerequisites, before diving deep into ReactJS:

  • HTML and CSS: Having a solid grasp of HTML for structuring web pages and CSS for styling is essential. React components often involve rendering HTML elements and styling them using CSS
  • JavaScript: React is built using JavaScript, so a good understanding of JavaScript fundamentals is crucial. 
  • Node.js and npm (Node Package Manager): React applications are typically developed with Node.js and use npm to manage dependencies. Install Node.js, and npm will come bundled with it. We need npm to install React and its related packages
  • Any text editor or IDE: Choose a code editor or IDE for writing React code. We can use IDEs such as, Visual Studio Code, Sublime Text, and WebStorm. 
  • Version Control (Optional): Familiarity with version control systems like Git is beneficial for tracking changes in your code and collaborating with other developers. 
  • Basic Command-Line Knowledge: Understanding basic command-line operations is helpful for setting up and managing React projects
  • HTTP and APIs: Many React applications interact with web services and APIs to fetch and send data. Understanding how HTTP requests work and how to work with RESTful APIs is valuable

History of React JS

  1. React JS was first released by Facebook in 2013. It was designed to simplify the process of building complex and dynamic web applications. It allows developers to create reusable components and use them across multiple pages.
  2. In 2015, Facebook released React Native, a mobile framework that allows developers to build native mobile applications using React syntax. It allows developers to build cross-platform applications that can run on both iOS and Android devices.
  3. Since then, React has become one of the most popular front-end development frameworks, with a large and active community of developers contributing to its development. In 2018, Facebook released React 16, which introduced several new features and improvements. It consisted of support for error boundaries and improved handling of asynchronous rendering.
  4. In 2020, Facebook released React 17, which focused on improving compatibility and stability across different versions of React. This release included several new features, improvements to the use effect hook and the ability to use JSX without importing React.
  5. As of 2022, React JS continues to be widely used and actively developed, with regular updates and improvements being released by Facebook and the React community.

Also Read, Front End Web Development

Features of React JS

Here are some of the key features of React JS:

Component-based architecture

React JS is built around the concept of reusable UI components that can be easily composed to create complex interfaces. This makes it easy to build and maintain large-scale applications.

Virtual DOM

React JS uses a virtual DOM, which is a lightweight version of the actual DOM. This allows React to quickly update the UI by comparing the virtual DOM to the actual DOM and making only the necessary changes.


React JS uses JSX, a syntax extension that allows developers to write HTML-like code in JavaScript. This makes it easy to build complex UI components in a familiar way.

One-way data flow

React JS uses a one-way data flow model. This means that data flows down from parent components to child components. This makes it easy to manage the state of an application and keep it in sync with the UI.

Unidirectional data flow

With React JS, data flows in a unidirectional manner from parent components to child components. This helps to keep the data flow organized and makes it easy to understand how data is passed between components.

React Native

React Native can be used to build native mobile applications. This allows developers to write mobile apps using the same codebase as their web applications. This can save time and reduce development costs.

Need of React JS

Here are some of the reasons why React JS is needed:

Component-based architecture

React JS allows us to break our application down into small, reusable components. This makes it easier to maintain and scale applications over time.

Declarative approach

With React JS, we can write code that describes what we want our UI to look like rather than how to achieve that result. This makes it easier to reason about our code and debug it.


React's virtual DOM, and component-based architecture makes it highly performant, even in complex applications.

Community support

React JS has a large and active community of developers, which means that there are many resources and libraries available to help us build our application.

Overall, ReactJS is a powerful technology that can help you build fast, scalable, and maintainable web applications.

Applications of React JS

Here are some common applications of ReactJS:

Single-page applications (SPAs)

React JS can be used to build SPAs that provide a more seamless user experience by dynamically updating the page content without reloading the full page.

E-commerce websites

React JS can be used to build e-commerce websites with real-time product updates, shopping cart functionality, and checkout processes.

Social media applications

React JS can be used to build social media applications with real-time data updates, user profiles, and messaging functionality.

Dashboards and data visualizations

React JS can be used to build dashboards and data visualizations that display complex data in an easily digestible format.

Gaming applications

React JS can be used to build gaming applications that provide a responsive and interactive user interface.

Content management systems (CMS)

React JS can be used to build CMS with rich text editors, media libraries, and other advanced features for managing and publishing content.

React JS vs. React Native

React JS and React Native are both frameworks developed by Facebook for building user interfaces, but they have different purposes and target different platforms.

ReactJSReact Native
Used in web application development.Used in mobile application development.
Runs in web browsers.Builds native mobile apps for iOS and Android.
Manipulates virtual DOM for web rendering.Uses native components for mobile rendering.
Some code reuse between web apps and native apps is possible through libraries like React Native Web.Code is not directly reusable between web and mobile apps.                                                                                  
Slightly slower compared to native apps.Generally faster, closer to native app performance.

Advantages of React JS

React JS is a popular JavaScript library that offers several advantages for web development, including

  • Declarative programming: React allows developers to describe the structure and behavior of their user interfaces in a declarative way, making it easier to understand and debug code.
  • Component-based architecture: React's component-based architecture allows developers to build reusable and modular UI components that can be easily combined to create complex interfaces.
  • High performance: React's efficient rendering system, and use of the virtual DOM makes it fast and performant, even with large and complex user interfaces.
  • Large community and ecosystem: React has a large and active community of developers who contribute to the library, provide support, and develop useful tools and extensions.
  • Compatibility with other libraries and frameworks: React JS can be easily integrated with other JavaScript libraries and frameworks, such as Redux, Angular, and Vue.
    Check out Advantages of React JS here.

Disadvantages of React JS

While React JS is a popular and widely used technology for web development, it also has some disadvantages that developers should be aware of. Here are the disadvantages of using React:

  • Steep learning curve: React has a relatively steep learning curve compared to some other front-end frameworks, and it can take some time to become proficient in using the library.
  • JSX syntax: React uses a syntax called JSX, which can be difficult to read and write, especially for developers who are not familiar with it.
  • No built-in support for routing and state management: React does not come with built-in support for routing or state management. This means that developers need to use additional libraries or frameworks to handle these functionalities.
  • Boilerplate code: React requires a lot of boilerplate code to set up and configure, which can be time-consuming and can make the codebase harder to maintain.
  • Performance issues on older browsers: React may not perform well on older browsers. This can limit the range of devices and platforms that a web application can support.

Limitations of Using React JS

While React JS is a powerful technology for building user interfaces, it also has some limitations. Here are some of the limitations of using React JS:

  • Limited functionality: React is a library for building user interfaces and does not provide features for other areas of web development, such as routing or state management. Developers may need to use additional libraries or frameworks to achieve these functionalities.
  • Complex setup: While React can be easy to use once set up, the initial setup can be complex and require knowledge of other tools and technologies, such as Node.js and Webpack.
  • Limited backward compatibility: React frequently releases updates, which can make it difficult to maintain backward compatibility with older codebases.

Frequently Asked Questions

Q. What is React JS?

React JS is a well-known JavaScript library for building user interfaces, developed by Facebook. React JS allows developers to create reusable UI components and manage their state efficiently. React uses a declarative approach to build UIs, meaning that developers only need to describe how the user interface should look at any given point in time, and React care of updating the DOM when the state of the application changes.

Q. What is ReactJS used for?

ReactJS is a popular open-source JavaScript library used for building user interfaces. We use ReactJS to build Mobile as well as Web applications. It supports server-side rendering(SSR) and is also used to develop applications that require real-time updates.

Q. Is React a front-end or backend?

React is a front-end JavaScript library used for building user interfaces (UI) for web applications. It is primarily used for front-end development, meaning it deals with the presentation layer of a web application.

Q. What language is used in ReactJS?

ReactJS is primarily written in JavaScript, which is the main language used for developing React applications. Additionally, developers often use JSX (JavaScript XML) for defining React components, which is a syntax extension for JavaScript. So, React applications are primarily built using JavaScript and JSX.


In this article, we discussed almost all the aspects of React JS. Starting from the history of React JS, we have seen what React JS is. We have also seen its features, needs, applications, advantages, disadvantages, and limitations. We have also discussed best practices and tips for using React JS and popular web applications that are built using React JS. Hope this article helped you to understand and enhanced your knowledge of the concepts of React JS.

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You can also consider our React Js Course to give your career an edge over others.

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