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What do you mean by “Virtual DOM”?

In this article, we will discuss Virtual DOM. You must be aware of the term “Virtual DOM” if you use or are...

Written by Rohit Sharma · 2 min read >

In this article, we will discuss Virtual DOM. You must be aware of the term “Virtual DOM” if you use or are learning React. Now, what is a “Virtual DOM” and why does React implement it?

Real DOM

DOM stands for “Document Object Model,” first and important. To put it simply, the DOM represents the user interface (UI) of your program. Any modifications to the user interface of your application are reflected in the DOM. The current issue is that performance is slowed down by frequent DOM manipulation.

Why is DOM manipulation slow?

As a tree data structure, the DOM is displayed. As a result, the DOM updates and changes happen quickly. The changed element and its children must then be re-rendered in order to update the user interface of the application. The UI is slow since it needs to be re-rendered or re-painted. As a result, as more UI components would require new rendering for each DOM update, the cost of DOM updates can increase as the number of UI components increases.‎

What is Virtual DOM?

This is where the idea of virtual DOM is useful because it outperforms real DOM by a wide margin. Only a virtual representation of the DOM exists in the virtual world. The virtual DOM is updated rather than the real DOM each time the state of our program changes.

Why is Virtual DOM faster?

A virtual DOM, which is seen as a tree, is produced when new UI elements are added. This tree’s nodes are its elements. A new virtual DOM tree is constructed whenever the state of any of these items changes.

Following this, the virtual DOM determines the most effective way to make these modifications to the real DOM. This guarantees that minimal operations are made to the real DOM. Consequently, updating the real DOM requires less processing power.

Using Virtual DOM in React

We’ll look at how React uses the virtual DOM now that you have a basic knowledge of what it is and how it might improve the performance of your project.

Each UI element in React is a component, and every component has a state. React follows the observable design and watches for state modifications. React updates the virtual DOM tree whenever the state of a component changes. React then contrasts the updated virtual DOM with its previous version after the virtual DOM has been changed. “Diffing” is the name of this process.

Once it has identified which virtual DOM items have changed, React only updates those objects in the real DOM. When compared to directly manipulating the real DOM, the performance is much improved as a result. As a result, React stands out as a quick JavaScript library.

Simply put, you tell React what state you want the UI to be in, and it ensures that the DOM represents that state. As a developer, you would not need to understand how to attribute manipulation, event handling, or manual DOM modifications take place behind the scenes, which is a massive benefit.

React developers are protected from all of these details. Simply update the component’s states as and when necessary; React will take care of the rest. The developer experience will be improved using React.

render() function in React

The UI is refreshed and rendered in render(). The necessary lifecycle method in React is render(). My blog post goes into great detail on React lifecycle methods.

The point of entry where the tree of React elements is built is the render() function. The render() function will return a different tree of React elements whenever a state or prop inside the component is changed. When a component uses setState(), React knows the state change and re-renders the component.

The UI is then effectively updated by React to reflect the most recent tree updates.

At this point, React only updates the objects that have changed in the real DOM and update its virtual DOM later.

Batch Update

React provides a batch update method to update the actual DOM. Therefore improving my performance. As a result, updates to the real DOM are sent in batches as compared to directly after just a state change.

React effectively maintains that only batch updates are sent to the real DOM in order to create the UI, which is the most expensive part of the process.


This article will help you to learn about Virtual DOM. Thank you for reading the article. Hope you understand very well about Virtual DOM.


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