How to concat and minify Javascript files really easily?

I'm teaching web development to beginners, and I want to show them how to concat and minify their Javascript files.

There are plenty of tutorials online on how to "concat and minify" with Grunt or Gulp, but they require a lot of installations & configurations. This is too complex for my needs.

Do you know any really simple way to do that? Something like a simple command line script to run manually:

> ./concatAndMinify foo.js bar.js output.js

I've been looking for hours with no success... Thanks!