In WordPress the whole React and ReactDOM libraries are exported into an object named wp.element. This is a global window element. And if you’ve worked with React before you know this is bit unusual compared to how React apps normally are setup. The big difference is that in a normal React app we import React, whereas in WP we don’t. Same for ReactDOM, as both are already loaded.
Tooling differences when using React in WordPress
The other major difference in working with React in WordPress is the tooling. And for those who already work with WP but are not as experienced in React this difference might actually make using React and ReactDOM easier. Normally React apps are built using various tools such as Create React App or other bundles of CLI tools. These tools generally don’t work with WP because need to avoid importing React.