How do I comment in CoffeeScript? "/* this */" doesn't work

Use a single # sign

# like this

One character seems pretty minimal ;)

Also:

###
This block comment (useful for ©-Copyright info) also gets 
passed on to the browsers HTML /* like this! */
###

The main way to comment is sh/Perl/Ruby/... style # comments:

# This comment goes to the end of the line
# and it won't appear in the "compiled"
# JavaScript version.

You use the block style ### comments when you want a comment to appear in the JavaScript version:

Sometimes you'd like to pass a block comment through to the generated JavaScript. For example, when you need to embed a licensing header at the top of a file. Block comments, which mirror the syntax for heredocs, are preserved in the generated code.

So if you start with

###
PancakeParser is Public Domain
###

then you'd get this JavaScript comment in the generated JavaScript:

/*
PancakeParser is Public Domain
*/

Beware of ###! If you use ### to separate sections of code (as I do) it's awfully surprising when that code stops working as a result.