What is React Js ?

React Js is an open source library built on top of java script for building user Interfaces.The maintenance of React Js is mainly looked after Facebook and Instagram.Here are few things to know about react.

Firstly, React js is not an opinionated software.
So, What is opinionated Software?
An opinionated software not only gives the language but also the approach for a developer to solve a business problem.It doesn't give the flexibility for the developer to solve the business problems by creating own set of rules.
whereas,
A non opinionated software gives the flexibility of creating own solutions in different approaches rather than the recommended one.Angular js is one good example of an opinionated software.Angular defines the language and also offers perfect rules and programming structure.It is necessary for the developer to follow the rules in order to use the product .
Whereas, React Js gives the flexibility to the developer to use their own approaches rather than sticking to few .Thus , react js can be termed as an non opinionated product.

2) React js doesn't use html as the view
MVC is a famous architecture which is followed by many applications all over the web."View" is the most important part of the application as its the only visible part to the user.Most of the frameworks use html to build their view but react uses java script in order to build the view.
See the sample layout below

Here we have three four different regions for our webpage.React considers these four different regions as four different components.
As all these components are built using java script, it's easy for us to place these components logically.A footer once built can be reused anywhere in the application.We can even listen to events and respond to the user by displaying dynamic data.These java script components  makes us easy to update our view without having the need of  reaching the server.
Reactjs is the "V" in the MVC architecture and is known as the library for creating user interfaces.

3) Languages that developers needs to learn before learning React js
It's good news again.React needs no extra languages expect the vanilla js. React js components are built using the vanilla js and there is no need for one to learn anything more than that. A good and a deep understanding of Java script and and higher order functions will do the job get done for you.
So why do you wait more, get started and learn react .