React  (the freeCodeCamp course)

React is a popular JavaScript library for building reusable, component-driven user interfaces for web pages or applications.

React combines HTML with JavaScript functionality into its own markup language called JSX. React also makes it easy to manage the flow of data throughout the application.

In this course, you'll learn how to create different React components, manage data in the form of state props, use different lifecycle methods like componentDidMount, and much more.