Understanding React

So, as we discussed, React is a JavaScript library for building user interfaces in web and mobile applications that utilize JavaScript. Later on in this chapter, we will use React with TypeScript, instead of JavaScript, but for a short while, we will focus purely on React, and thus, deal with the only JavaScript. For a more in-depth documentation on React, refer to https://facebook.github.io/react/.

React is declarative

When we use React, we have an option to use JSX, which gives us a markup-style syntax, which is then compiled to procedural JavaScript code. JSX stands for Syntax Extensions for JavaScript. Consider the following statement:

const helloElement = <h3>Hello, {user.name}</h3>; 

It is not pure JavaScript, nor is it pure HTML--it is something in between. It definitely mixes JavaScript and HTML in a very powerful and expressive way. In JSX, you wrap JavaScript inside the XML style markup using curly braces, and you can close your tag with />, as follows...