The React.js Library

What is React?

React.js, commonly known as React, is an open-source JavaScript library used for building user interfaces or UI components, particularly for single-page applications where UI updates are frequent.

React allows developers to create reusable UI components and manage the state of the application efficiently. One of its key features is the ability to build a virtual DOM (Document Object Model), which is a lightweight copy of the actual DOM. This virtual DOM is used to improve performance by minimizing direct manipulation of the actual DOM, updating only the necessary parts when changes occur.

React vs JavaScript

It’s a bit like comparing apples and oranges because React and JavaScript serve different purposes. Let’s see:


  • Definition: JavaScript is a programming language that enables you to add interactivity, manipulate the DOM, and control the behaviour of a web page.
  • Usage: It’s a versatile language used for both client-side and server-side development. On the client side, it’s mainly used for enhancing the user experience in web browsers. On the server side, with the advent of technologies like Node.js, JavaScript is used for server-side scripting as well.
  • Features: JavaScript is a full-fledged programming language with its own set of features, and it provides the foundation for many web development frameworks and libraries.


  • Definition: React is a JavaScript library for building user interfaces. It provides a way to structure UI components and manage the state of an application efficiently.
  • Usage: React is specifically designed for building user interfaces, particularly in the context of single-page applications. It simplifies the process of creating interactive and dynamic UIs by introducing a component-based architecture.
  • Features: React introduces concepts like a virtual DOM, JSX (a syntax extension for JavaScript), and a unidirectional data flow. It’s mainly used for building reusable UI components and managing the state of these components.

In summary, React is a library written in JavaScript. When people talk about “React vs JavaScript,” they might be referring to using raw JavaScript (without any libraries or frameworks) versus using React to build UI components in a more structured and modular way. React itself relies on JavaScript for its functionality, so it’s not accurate to compare them as if they are mutually exclusive. Instead, React is a tool that makes it easier to work with JavaScript when building complex user interfaces.

React vs Angular

React is often referred to as a library because it focuses primarily on the view layer of an application. It provides a component-based architecture to build UIs.

Angular is a full-fledged MVC (Model-View-Controller) framework that provides a more opinionated structure for building web applications. It includes not only the view layer but also tools and conventions for managing the entire application.

React is commonly chosen for its flexibility, especially in projects where the focus is on building user interfaces. Angular is often preferred for larger enterprise-level applications that benefit from the structure and conventions provided by a full MVC framework.

Limitations of React.js

While React has become one of the most popular libraries for building user interfaces, like any technology, it comes with its set of limitations. Here are some of the limitations of React:

  • Learning Curve: For beginners, the learning curve might be steep, especially when concepts like JSX, virtual DOM, and component lifecycle are new. Additionally, understanding the ecosystem and choosing the right tools (e.g., state management libraries) can add complexity.
  • Boilerplate Code: React applications can sometimes involve writing a significant amount of boilerplate code, which may be seen as a drawback compared to more opinionated frameworks that provide conventions for certain tasks.
  • View Focus: React is primarily a library for building user interfaces, so if you need a full-fledged framework with built-in tools for routing, HTTP requests, and state management, you might need to integrate additional libraries or frameworks.
  • Tooling Overhead: While React itself is lightweight, setting up a development environment with tools like Babel, Webpack, and other build tools may add some initial complexity, especially for beginners.
  • Large Bundle Sizes: As React applications grow, the size of the JavaScript bundles can become a concern. While tools like tree-shaking and code splitting can help mitigate this, developers need to be mindful of the overall bundle size for optimal performance.
  • Integration with Legacy Code: If you’re working with an existing codebase that doesn’t use React, integrating React into it may require additional effort. This is especially true if the application relies heavily on other frameworks or technologies.
  • Rapidly Changing Ecosystem: The JavaScript ecosystem, including React and its associated libraries, evolves quickly. This can make it challenging for developers to keep up with the latest best practices and tools.
  • Decision Fatigue: React’s flexibility means that developers have many choices for state management, routing, and other aspects. While flexibility is an advantage, it can also lead to decision fatigue, especially for newcomers who may find it challenging to choose the right tools for their project.

Despite these limitations, React has proven to be a powerful and widely adopted tool for building modern user interfaces. Many of these limitations can be mitigated with experience, good development practices, and the use of additional libraries or tools as needed for specific project requirements.