What is React Js?

Last updated : April 11, 2023

React Js is one of the most popular front-end libraries to develop UI applications today. In this article, I'll introduce you to React Js and its origins and provide an overview of what makes it so popular among web developers.

What is React Js?

React Js, often called React, is an open-source JavaScript library for building efficient and interactive user interfaces for web and native applications. Developed by Facebook, React has gained immense popularity among developers for its simplicity, reusability, and performance. With React, you can create complex UIs by breaking them down into smaller, independent, and reusable components.

A Brief History of React

Jordan Walke, a software engineer at Facebook, created React Js in 2011. React is intended to improve the performance and maintainability of Facebook's web applications. React was first introduced in 2013. Today, React is maintained by Facebook and a community of individual developers and companies. Many organizations like Airbnb, Netflix, and Instagram use React Js.

Why React Js?

There are several reasons why React has become a popular choice for building web applications. Below are some.

  1. Component-based architecture: React allows you to create modular, reusable components that can be easily combined and managed, making your codebase more organized and maintainable.
  2. Virtual DOM: React uses a virtual representation of the actual DOM (Document Object Model) to track changes in the UI. That allows React to perform efficient updates and minimize the need for time-consuming DOM manipulations.
  3. Server-Side Rendering: React Server Side Rendering (SSR) is a technique where a React application is rendered on the server instead of the browser, generating static HTML that is sent to the client. SSR improves initial load time, enhances SEO, and provides better performance for slow or unreliable connections.
  4. React Hooks: Introduced in React 16.8, hooks are a powerful feature that enables you to use state, and other React features in functional components without needing to convert them to class components.
  5. Strong community and ecosystem: React boasts a large and active community of developers, which translates to an abundance of libraries, tools, and learning resources.
  6. Seamless integration: React can be integrated with other JavaScript libraries and frameworks, allowing you to leverage its benefits in existing projects.

What is so special about Virtual DOM?

The Virtual DOM concept is one of my favorites in React Js. It is one of the key features that sets React Js apart from other JavaScript libraries and frameworks. It is an in-memory, lightweight representation of the actual DOM (Document Object Model) that significantly improves performance in React applications. Remember how cool it was to manipulate the DOM with JQuery several years ago? That is highly inefficient due to the browser re-rendering the entire DOM. Here are some critical tasks virtual DOM performs that makes it so special. That's how it contributes to better performance.

  1. Batching and minimizing DOM manipulations: The primary reason behind the Virtual DOM's enhanced performance is its ability to reduce the number of direct DOM manipulations. Direct manipulation of the DOM is slow and resource-intensive, mainly due to the need for browser layout recalculations and repaints. React batches multiple updates and only modifies the actual DOM when it's most efficient. That dramatically improves the overall rendering performance of a web application.
  2. Efficient diffing algorithm: React uses "Reconciliation" to compare the current Virtual DOM with the updated Virtual DOM when changes occur in the application. React's efficient diffing algorithm, called the "Diffing Algorithm," quickly identifies the differences (or "diffs") between the two Virtual DOM representations. By only updating the parts of the actual DOM that have changed, React minimizes the number of required updates, leading to better performance.
  3. Simplified programming model: The Virtual DOM enables developers to write code as if the entire page is re-rendered on each update, even though only the necessary changes are applied to the DOM. This simplified programming model reduces the complexity of managing the UI state and allows developers to focus on building the application logic.
  4. Predictable and controlled UI updates: React's component-based architecture, combined with the Virtual DOM, ensures that UI updates are predictable and controlled. That means when a component's state or properties change, React intelligently determines the minimal updates required for the actual DOM to reflect those changes. This predictability results in more maintainable code and fewer performance issues.

The Virtual DOM leads to faster rendering times, a simplified programming model, and more predictable UI updates.

React Js virtual DOM
Figure 1 : React Js virtual DOM

React's Core Concepts

Before diving deeper into React, it's essential to understand a few core concepts:

  1. Components: Components are the building blocks of a React application. They are self-contained, reusable pieces of code that define how a particular UI part should look and behave.
  2. JSX (JavaScript XML): JSX is a syntax extension for JavaScript that allows you to write HTML-like code within your JavaScript code. It makes writing React components more intuitive and visually clear.
  3. Props: Props (short for properties) are a way to pass data from a parent component to a child component in React. They make components more flexible and reusable by allowing customization.
  4. State: State represents the internal data of a component. When a component's state changes, React automatically re-renders the component to reflect the updated data.

What are the advantages of React Js compared to Angular Js and Vue Js?

While React, Angular, and Vue are popular JavaScript libraries and frameworks, each has unique advantages. Here are some key benefits of React compared to Angular and Vue:

  1. Flexibility: React is a library focused on the view layer, allowing developers to choose other libraries and tools for tasks like state management, routing, and form validation. That flexibility enables developers to tailor their tech stack to their project's requirements.
  2. Virtual DOM: React pioneered the Virtual DOM concept, which optimizes rendering by minimizing direct DOM manipulation. While Angular and Vue have adopted similar strategies, React's implementation is highly efficient and mature, resulting in an excellent performance.
  3. Strong Community and Ecosystem: React has a large, active community and a vast ecosystem of libraries and tools. That translates into abundant learning resources, tutorials, and third-party packages, enabling faster development and problem-solving.
  4. React Native: React allows for easy transitioning to mobile development using React Native, a popular framework for building cross-platform mobile applications. Angular and Vue have their solutions (NativeScript and Vue Native), but React Native is widely considered more mature and stable.
  5. Backing by Facebook: React's development and maintenance by Facebook provide a sense of stability and a long-term commitment to the library, instilling confidence in developers and organizations adopting it.
  6. Improved Reusability: React's component-based architecture and unidirectional data flow promote the creation of highly reusable and maintainable components, resulting in more organized code.
  7. Wide Adoption: React is used by many large organizations, including Facebook, Instagram, Airbnb, and Netflix, reinforcing its credibility and effectiveness.

I don't mean that React Js doesn't have any disadvantages. Below are some key points to consider.

Disadvantages of React Js compared to Angular Js and Vue Js

  1. Learning Curve: React introduces new concepts like JSX, Virtual DOM, and component lifecycle, which may be challenging for beginners. Angular has a steeper learning curve due to its extensive feature set and TypeScript, while Vue is known for its simplicity and ease of learning.
  2. Lack of Official Guidelines: React is flexible, but this flexibility can be a double-edged sword. The lack of official guidelines for structuring applications or managing state may result in inconsistency across projects. Conversely, Angular has a well-defined structure, and Vue Js balances flexibility and convention.
  3. Not a Full-Featured Framework: React is a library focused on the view layer, so additional libraries are required for tasks like routing, form validation, and state management. That contrasts with Angular, a complete framework offering built-in solutions for such tasks. While still a library, Vue Js provides official state management and routing packages.
  4. Frequent Updates: The React ecosystem evolves rapidly, leading to frequent updates that may require developers to learn new best practices and update their code constantly. Angular and Vue updates tend to be more conservative with changes that impact developers.
  5. Overhead for Small Projects: React's focus on modularity and reusability can result in overhead for smaller projects that may not benefit from its advanced features. Vue is often recommended for small projects due to its simplicity and low overhead.
  6. Verbosity: React Js can be more verbose than Vue, especially when handling component state and props. Vue's concise syntax and features like computed properties can produce cleaner, more readable code.
L Raney
By: L Raney
Lance is a software engineer with over 15 years of experience in full-stack software development.

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