As we saw in the preceding section, JSX has special syntax that lets us embed JavaScript expressions. Any time we render JSX content, expressions in the markup are evaluated. This is the dynamic aspect of JSX content, and in this section, you'll learn how to use expressions to set property values and element text content. You'll also learn how to map collections of data to JSX elements.
Some HTML property or text values are static, meaning that they don't change as the JSX is re-rendered. Other values, the values of properties or text, are based on data that's found elsewhere in the application. Remember, React is just the view layer. Let's look at an example so that you can get a feel for what the JavaScript expression syntax looks like in JSX markup:
import React from 'react';
import { render } from 'react-dom';
// These constants are passed into the JSX
// markup using the JavaScript expression syntax...