What is ReactJS?
React is Flexible
React is remarkably flexible. Once you have learned it, you can use it on a vast variety of platforms to build quality user interfaces. React is a library, NOT a framework. Its library approach has allowed React to evolve into such a remarkable tool.
Rapid development and React’s small API combined to create a fantastic developer experience. React’s API is very simple to learn. It has very few concepts to learn.
React is heavily used in the Facebook app, website, and in Instagram. That’s why Facebook is deeply committed to it.
Components are the building blocks of any ReactJS application, and a single app usually consists of multiple components. These components have their logic and controls, and they can be reused throughout the application, which in turn dramatically reduces the application’s development time.
Unidirectional data flow
React follows a unidirectional data flow. This means that when designing a React app, developers often nest child components within parent components. Since the data flows in a single direction, it becomes easier to debug errors and know where a problem occurs in an application at the moment in question.
ReactJS keeps a lightweight representation of the “real” DOM in the memory, and that is known as the “virtual” DOM (VDOM). Manipulating real DOM is much slower than manipulating VDOM because nothing gets drawn on the screen. When the state of an object changes, VDOM changes only that object in the real DOM instead of updating all of the objects.
React uses VDOM, which makes the web applications run much faster than those developed with alternate front-end frameworks. React breaks a complex user interface into individual components, allowing multiple users to work on each component simultaneously, thereby speeding up the development time.
ReactJS applications are easy to test due to a large developer community. Facebook even provides a small browser extension that makes React debugging faster and easier. This extension, for example, adds a React tab in the developer tools option within the Chrome web browser. The tab makes it easy to inspect React components directly.