WHAT-IS-REACT-JS

What is React Js

React is a JavaScript library for building user interfaces.

React is used to build single-page applications.

React allows us to create reusable UI components.

React, sometimes referred to as a frontend JavaScript framework, is a JavaScript library created by Facebook.

React is a tool for building UI components.

React creates a VIRTUAL DOM in memory.

Instead of manipulating the browser's DOM directly, React creates a virtual DOM in memory, where it does all the necessary manipulating, before making the changes in the browser DOM.

React only changes what needs to be changed!

React finds out what changes have been made, and changes only what needs to be changed.

You will learn the various aspects of how React does this in the rest of this tutorial.

To understand how React works, we first need a basic understanding of how browsers interpret your code to create interactive user interfaces (UI).

When a user visits a web page, the server returns an HTML file to the browser that may look like this:

The browser then reads the HTML and constructs the Document Object Model (DOM).

What is the DOM?

The DOM is an object representation of the HTML elements. It acts as a bridge between your code and the user interface, and has a tree-like structure with parent and child relationships.

Hear HTML is parent body is a child, like wise it will act.