How does React work under the hood?

Have you ever wondered how the ever-popular React framework actually works and how it enables developers to create advanced web applications and apps? To truly understand the workings and benefits of React, it is important to understand how it works behind the scenes.

Recent advancements in web development have highlighted the need for reactive frameworks that are easy to use for engineers and developers new to a given programming language. React is a popular javascript library that has been used for many years and has been adopted by many leading web development services. Despite its popularity, questions remain regarding how the JavaScript library workloads and functions on the back-end.

Milton Jones, an experienced React application developer, provides an in-depth insight into the topics of reactivity, the structure of the codebase, and how the library works under the hood. Drawing from years of experience developing applications with React, Milton offers a comprehensive overview of the workings of the library.

In this article you will learn what goes on under the hood when using React. Milton follows the structure of the library codebase and explains what goes on in each step from initialization to the code execution process. Furthermore, he takes the time to break down the concept of reactivity and demonstrate the potential impacts this can have on the overall performance of React applications.

React: React is a popular JavaScript library created by Facebook for building user interfaces. It is a component-based library that allows developers to create composable user interfaces and think in terms of discrete components.

Under the hood: Under the hood, React works with the Virtual DOM, a virtual representation of the actual DOM (Document Object Model). React uses the Virtual DOM to keep track of the changes to the UI and only updates the real DOM when necessary. This makes React more efficient and performant than other JavaScript libraries.

Components: React components are pieces of code that are responsible for building, styling, and managing UI elements. Components are reusable and often contain states, props, lifecycle methods, and other data related to their functions. These components are then composed together to create larger UI elements, such as entire pages.

JSX: JSX is a markup language that is used to write React components. It works similarly to HTML and is often used to define the UI elements of components. JSX is a powerful tool for making React code more concise and readable, and is widely used by React developers.

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ReactDOM: ReactDOM is a library that is used to render React elements into the DOM. It provides an API for interacting with the actual DOM, allowing developers to easily update UI elements and keep track of the current state of the application.

Heading 1: What is React?

React is a JavaScript library that is used to develop user interfaces (UIs). It is maintained by Facebook and a community of individual developers and companies. React allows you to create and manage UIs with more capable and efficient features than purely static HTML pages allow.

The most fundamental concept of React is its use of components. Components are reusable pieces of code which can be used to define different parts of a UI with a consistent look and feel. React components are also designed to function independently from other parts of the application, making them easy to reuse and customise.

In addition to components, React also makes use of two other core principles: virtual DOM and unidirectional data flow. The virtual DOM is a virtual representation of the DOM that facilitates faster updates and more efficient memory usage; unidirectional data flow ensures that all changes to the UI are based on the current state of the application, rather than on user input.


ReactDOM is a core part of the React library that makes it possible to render React components into the DOM. By using ReactDOM, React applications are given access to the browser’s document object model (DOM), allowing them to render HTML elements and attach event handlers.

React Native

React Native is a framework for building native mobile applications with React. It is based on the same core principles as React but provides a set of APIs that are tailored to mobile devices. React Native enables a more efficient development cycle and a smoother transition from design to production, allowing developers to rapidly create beautiful and user-friendly mobile UIs.

  • Components
  • Virtual DOM
  • Unidirectional Dataflow
  • ReactDOM
  • React Native

Heading 2: How React Works Under the Hood

“Programs must be written for people to read, and only incidentally for machines to execute.” – Harold Abelson

React is a JavaScript library used for developing user interfaces. It provides a series of components that are reusable and easy to use, and also works with different technologies and frameworks. In order to understand how React works under the hood, one must first know what transpiring happens when a React application is built.

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The Building Blocks of React

At its simplest, React is a JavaScript library that uses components to create a user interface. These components can be composed of other components to create complex user interfaces. It also has features like a virtual DOM to optimize the performance of an application.

Virtual DOM

The virtual DOM is a representation of the actual user interface in JavaScript memory. React uses the virtual DOM to keep track of the state of the application and to render the application based on the user’s interactions. Whenever a change is made to a component, React updates the virtual DOM and then re-renders the application accordingly. This allows for a faster and more efficient user experience.


JSX is a syntax extension to JavaScript that allows for HTML-style markup tags to be used in React components. This allows developers to write components using HTML-like syntax and makes the code more efficient and easier to read.

Finally, React uses the ES6 (EcmaScript 2015) version of JavaScript. This version of JavaScript introduces modern features such as classes, arrow functions, and more. The ES6 version of JavaScript allows developers to write better, more efficient code.

By combining all of these elements, React is able to create complex, reactive user interfaces in a powerful and efficient way. It is this combination of features that allows React to be used for developing high-performance user interfaces.

Heading 3: How React Enhances User Experience

“A computer without COBOL and Fortran is like a piece of chocolate cake without mustard and ketchup.” – unknown

React is a popular library used to create powerful and dynamic user interfaces. By using it, the user experience is greatly enhanced compared to traditional programming languages. React makes it easier to create responsive and interactive websites. It also offers developers the flexibility to create applications with multiple components that can interact with each other.

Creating Responsive Websites with React

One of the core features of React is its ability to make web sites responsive and interactive. It uses a virtual DOM (Document Object Model) that allows developers to quickly and efficiently make updates to the HTML code. This virtual DOM facilitates the use of React’s powerful set of components to create web sites with complex user interactions. Furthermore, it allows developers to easily add new components and create responsive versions of already existing components.

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Accessing Components from React

React gives developers access to components through a set of APIs. These APIs can be used to access and manipulate individual components. With the help of these APIs, developers can create interactions between components and make changes to them without having to manually edit the source code. The components can be rapidly edited without the need to restart the entire application. React also makes it easy to debug and troubleshoot components by allowing developers to view the entire source code in an organized way.

By using React, developers can easily create powerful and interactive applications. Furthermore, React provides the flexibility to create and maintain complex web applications with ease. The availability of components and APIs makes it easy for developers to create responsive and interactive web sites with fewer efforts.


Have you ever wondered how React works to make your application run smoothly? It’s a mysterious and complex process, but one of crucial importance to developers. React acts as a bridge between the user, the code, and the browser, delivering the best user experience. It’s not only the engine behind most web applications, but it also helps in reducing development time and lowers costs with added efficiency.

To learn more about React and its powerful capabilities, be sure to follow our blog. We’ll be sure to keep you informed with the latest releases, news and tips on using the platform. You’ll be able to stay up to date on the newest developments and see the amazing potential of React for yourself. So don’t wait – start using React to create the best user experience for your applications today.

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