React Virtual DOM Explained in Simple English

If you are using React or learning React, you must have heard of the term “Virtual DOM”. Now what is a Virtual DOM, and why does React use it?

Real DOM

First things first, DOM stands for “Document Object Model”. The DOM in simple words represents the UI of your application. Everytime there is a change in the state of your application UI, the DOM gets updated to represent that change. Now the catch is frequently manipulating the DOM affects performance, making it slow.

What makes DOM manipulation slow?

The DOM is represented as a tree data structure. Because of that, the changes and updates to the DOM are fast. But after the change, the updated element and it’s children have to be re-rendered to update the application UI. The re-rendering or re-painting of the UI is what makes it slow. Therefore, the more UI components you have, the more expensive the DOM updates could be, since they would need to be re-rendered for every DOM update.

Virtual DOM

That’s where the concept of virtual DOM comes in and performs significantly better than the real DOM. The virtual DOM is only a virtual representation of the DOM. Everytime the state of our application changes, the virtual DOM gets updated instead of the real DOM.

Well, you may ask ” Isn’t the virtual DOM doing the same thing as the real DOM, this sounds like double work? How can this be faster than just…