Use process.version:

The version property of the process object returns a string with the current Node.js version.

In the browser, the process object is not defined, so you get a ReferenceError:

Another way is to reference process.versions (plural):

This returns an object that contains various properties referencing each component’s version.

To get the major version (in this example, 12), you can use

process.versions.node.split('.')[0]

Lessons in this unit:

0:	Introduction
1:	The Node Core Modules
2:	Differences between Node and the Browser
3:	Node, the difference between development and production
4:	The Node.js Event Loop
5:	A brief history of Node.js
6:	Understanding process.nextTick()
7:	Understanding setImmediate()
8:	▶︎ How to check the current Node.js version at runtime
9:	Why should you use Node.js in your next project?
10:	Introduction to Node.js