React JS is an efficient, flexible and powerful JavaScript library for building user interfaces. Developed by Facebook, React JS aspires to improve upon the traditional methodologies of building interfaces by enabling developers to break them down into reusable components instead of using frameworks like Angular or Ember. Developers can build large web applications that are scalable and dynamic.
React JS works by breaking down the user interface into small, reusable and manageable pieces called components. Each component represents a specific aspect of the application, such as a search bar, a navigation menu or a button, which developers can combine to create the overall application. It makes the user interface incredibly responsive through its virtual DOM (Document Object Model). The virtual DOM ensures that it only renders the changes made to the user interface rather than re-rendering the whole thing again, boosting the application’s performance.