Introducing React

React is a JavaScript library created by Facebook. While AngularJS positions itself as a framework, React is very clear in its position as a library. React prides itself on being responsible for the visual aspect of the application, "Just the UI", as the React landing page professes. By concerning itself modularly with this single aspect, React is relatively small in size compared to AngularJS and other one-stop-shop frameworks.

React employs a modular approach to the UI, with the idea of components. Components are similar to the directives we used with AngularJS and to the idea of web components. That is, components are reusable pieces of UI functionality, adhering to the "do one thing, do one thing well" ideology. React really pushes the modular approach in how components are usually composed, with tight coupling between styles, HTML, and JavaScript.

Typically, all component specific code is contained within one file. The HTML, the CSS rules, and the...