React is a JavaScript library created for building fast and interactive user interfaces for web and mobile applications. It is an open-source, component-based, front-end library responsible only for the application’s view layer. In Model View Controller (MVC) architecture, the view layer is responsible for how the app looks and feels.

Because React is easy creation of dynamic applications,Improved performance,Reusable components,Unidirectional data flow,It can be used for the development of both web and mobile apps

Javascript is a dynamic programming language which is widely used for developing web applications. It is very lightweight and is supported by most of the modern browsers. Moreover, JavaScript supports both object-oriented programming and procedural programming. Thus, it is used for creating web pages with a client-side script to interact with the user and make the web pages dynamic and robust.