Node.js has increased dramatically in popularity and is supported with a tutorial on W3Schools: https://www.w3schools.com/nodejs/default.asp
It has a wide range of real world uses and can serve as the main server in lighter applications with low to medium traffic (depends on hardware, etc.)
It is also used in real heavy applications in fact - but in that context not as the primary server.
In heavy applications, it is very popular to use Node.js for "microservices".
With microservices: Another server like Apache HTTPD, Tomcat or the newer Glassfish can serve as the primary server dealing with the heavy load.
The microservice approach can among other things, take a variety of lighter sub-applications off the primary server - to be handled on other machines using Node.js.
An easy way to get started is with JavaScript Servlets. http://hll.nu/achieve
