how does the JavaScript work with DOM or VDOM in Browser?

how does the JavaScript work with DOM or VDOM in Browser?

The Document Object Model (DOM) is the data representation of the objects that comprise the structure and content of a document on the web. This guide will introduce the DOM, look at how the DOM represents an HTML document in memory and how to use APIs to create web content and applications.

What is the DOM?
The Document Object Model (DOM) is a programming interface for web documents. It represents the page so that programs can change the document structure, style, and content. The DOM represents the document as nodes and objects; that way, programming languages can interact with the page.
A web page is a document that can be either displayed in the browser window or as the HTML source. In both cases, it is the same document but the Document Object Model (DOM) representation allows it to be manipulated. As an object-oriented representation of the web page, it can be modified with a scripting language such as JavaScript.
For example, the DOM specifies that the querySelectorAll method in this code snippet must return a list of all the

elements in the document:
const paragraphs = document.querySelectorAll("p");
// paragraphs[0] is the first

element
// paragraphs[1] is the second

element, etc.
alert(paragraphs[0].nodeName);

All of the properties, methods, and events available for manipulating and creating web pages are organized into objects. For example, the document object that represents the document itself, any table objects that implement the HTMLTableElement DOM interface for accessing HTML tables, and so forth, are all objects.
The DOM is built using multiple APIs that work together. The core DOM defines the entities describing any document and the objects within it. This is expanded upon as needed by other APIs that add new features and capabilities to the DOM. For example, the HTML DOM API adds support for representing HTML documents to the core DOM, and the SVG API adds support for representing SVG documents.

Virtual DOM

React creates elements for itself using its createsElements () function. By combining all the elements, he creates a separate dom inside himself. This dom is called Virtual Dom. React's virtual dom basically renders as much as the browser's dom has changed.

We can imagine the Virtual Dom as a simple tree. The different notes of which are one component. Whenever we change the state of a component, a tree is created first. Where the modified component and its child components are reconstructed. That is, React has two representations of the virtual dom. One is the state before it, and the other is the state after the change. React compares these two conditions.