What is JSX?

In this section, we'll implement the obligatory hello world JSX application. At this point, we're just dipping our toes into the water; more in-depth examples will follow. We'll also discuss what makes this syntax work well for declarative UI structures.

Hello JSX

Without further ado, here's your first JSX application:

// The "render()" function will render JSX markup and 
// place the resulting content into a DOM node. The "React" 
// object isn't explicitly used here, but it's used 
// by the transpiled JSX source. 
import React from 'react'; 
import { render } from 'react-dom'; 
 
// Renders the JSX markup. Notice the XML syntax 
// mixed with JavaScript? This is replaced by the 
// transpiler before it reaches the browser. 
render( 
  (<p>Hello, <strong>JSX</strong></p>), 
  document.getElementById('app') 
); 

Pretty simple, right? Let's walk through what's happening...