Lets say one of my friend posted photographs on instagram .and you like the image also checking out the comments you see that likes count up increased by 100 since you liked the image even without reloading the app this magical count is because of react.js

React is flexible and efficient JavaScript library for building user interface also its is open-source component based frontend of the application As you know it efficiently update and render just the right component when your data changes and easier to debug.

React.js is not a framework developed and maintained by facebook for solving some troubles that we are facing earlier.

Why React

Facebook developers realized that the DOM is slow then how we make it faster then facebook developers developed library called React that implements a virtual DOM so when it needs to read and write to the DOM,It will use the virtual representation of it then the virtual DOM will try to find the most efficient way to update the brower’s DOM also React elements are simple objects and are contemptible to make React DOM updating the DOM to match the react elements