March 1, 2024


Tiny articles, big solutions.

React Virtual Dom: Simplest Way to Understand the Basics


The front-end ecosystem of application development has been ever-evolving and changing with time. Some tools have gained the title of “best-sellers” for web application development due to their ability to revolutionize the workflow. In this break-neck competition of the best tools, some shine, while some fade away.

One of the tools that outshone in a substantial competition is ReactJS. It was released back in 2013 as a javascript library. Since then, it has quickly generated an on-going buzz around it due to the excellent functionalities and benefits it provides to an application. 

Currently, Facebook maintains ReactJS, along with a community of developers.

Leading companies like Apple, Netflix, and Paypal along with 32 thousand more applications, enjoy providing the “React Support” to their apps.

You too can add your name into the prominent reactjs list if you Hire ReactJS programmers to work on your upcoming project. 

ReactJS is famous for several reasons like: 

  • It facilitates the overall process of writing components
  • It provides productivity boost and facilitates further maintenance
  • It makes sure your app renders faster
  • ReactJS is a guarantee of stable code
  • It is friends with SEO
  • It provides developers with a helpful toolset
  • Mobile app development can be facilitated with React Native

If you now set on using ReactJS for developing your web application, there might be one term that may seem perplexing to you; it is called “Virtual DOM.” 

While your developer works on your application using React, it would be useful to understand what s/he is doing and what it is all concerned with. 

Therefore, in this article, we will cover a comprehensive explanation about:

  • What is Virtual DOM?
  • How is it different from the Real DOM?
  • Characteristics of a virtual DOM
  • Benefits provided by ReactJS Virtual DOM

What Is Real Dom? 

Let’s start with the basics; DOM is an acronym of “Document Object Model.” The DOM represents the UI of an application, so every time your application’s state changes, the DOM will get updated to represent the change.

Now the weak point here is that if you frequently manipulate the DOM, your application’s performance can drastically decrease, making it slow.

How does DOM manipulation make your app slow?

The DOM represents the data in a tree-like structure due to which any change/update to the DOM is quick. However, once the change is implied in one element, its sub-elements also have to be re-rendered to update the app’s UI. It is the re-rendering of this UI that decelerates the performance. 

Therefore, if you intend to embed numerous UI components, you will have to update your DOM for each element (which could be expensive).

What is Virtual DOM?

The performance lack real DOM possesses brought forth the concept of a Virtual DOM. The performance of a virtual DOM is significantly better than the real DOM. The virtual DOM ReactJS inherits a virtual representation of the real DOM; therefore, every time our application’s state changes, the virtual DOM is updated (rather than the Real DOM).   

Well, you may have your doubts. It is okay if questions like “isn’t real DOM doing the exact same thing? How is virtual DOM better? Isn’t it double the work?” Are popping up in your mind.

Because we have answers to that.

Simply the virtual DOM is much faster and efficient than the real DOM.

How is Virtual DOM Faster? 

When a new element is added in the UI, a virtual DOM is created (represented as a tree). Each component of this tree is a node. If any element in this state changes, a virtual DOM is created. Then this tree is compared to the previous DOM tree. 

Once the changes are done, the Virtual DOM calculates the best possible way to implement them into the real DOM. The process makes sure that the real DOM goes through as minimal operations as possible. 

Image Source:

The red circles represent the changed nodes, i.e., the UI elements with the altered states. The difference between the previous virtual DOM and the current virtual DOM is then calculated, then the entire parent subtree gets re-renders to portray the updated UI elements. 

The updated elements are updated to the real DOM.

How does ReactJS use Virtual DOM?

Now that you understand how virtual DOM helps you increase your application’s performance, let’s look into ways to leverage its functionalities: 

In ReactJS, every single UI piece is an element, and each component has a state. React follows the “observable pattern” by listening to the state changes.

When the state of an element is changed, it is updated in the virtual DOM by ReactJS. Once the virtual DOM is updated, React compares the current and previous versions of it. The process is called “diffing.”

In layman terms, you tell React what states you want your elements to be in, and it ensures that the DOM matches your requirements. 

You can further increase your DOM’s functionality if you hire a ReactJS developer. You can ask your developer to update all components as and when needed using react js. 

There are two ways to do that:

  • React Render() Function:

Render is where the UI is updated and rendered. It is the entry point from where the react element tree starts. When a component state is updated, render() will return a different tree of React elements. 

If you imply set state() within the component, the React detects the changed state and re-renders the element.

  • Batch Update:

ReactJS uses a batch update mechanism to facilitate the updating of real DOM. Therefore, performance is increased. This implies that batches of updates are sent to the Real DOM, instead of throwing in single updates of state change. 

UI elements require expensive repainting, which can be avoided since ReactJS sends only batched updates to the DOM. 

Benefits ReactJS virtual DOM provides: 

  • Efficiency:

It is understood now that React’s virtual DOM provides a better and effective way to update the components of a web application. Each time an underlying data is changed in the React app, a new virtual DOM representation is created. 

  • Higher Performance:

If you decide to update the virtual DOM to React, you choose to increase your app’s performance. Using the setStare() method, ReactJS can create a whole new virtual DOM from scratch. Developing an entire tree is quick. Therefore, it increases performance in a considerable amount. 

  • Simplicity:

If we look from a developer’s perspective, React, and the virtual DOM it possesses are much simpler than the rest. Pure JS codes update the React components while the React updates the DOM.

  • CPU-Intensive:

The Virtual DOM provides an added layer of scripting to the optimizations carried out by the browser to make the DOM manipulations clearer to the developer. Compared to other DOM updating methods, this method has proven to be much more CPU-intensive. 

  • Optimized Memory Usage:

React’s Virtual DOM makes optimized use of memory compared to the other systems, as it holds no observables in the memory. 

Parting Thoughts:

If you wish to opt for the ReactJS development of your application, you will have to hire ReactJS programmers to facilitate the task. However, you must know the transition your app is going through. 

We hope the article effectively provides a clear view of how ReactJS makes effective use of the Virtual DOM and why it is better than the real DOM.