<p>I'd like to have comments in my code, but I want them to be removed before deploying.
Yes, it's not hard to write such a thing, but if it already exists…
And how about comments in ASP pages?</p>

Sounds like you are looking for a JSMin tool or similar.
There are many tools which you can purchase, but there are also some online tools you can use:
http://www.askapache.com/tools/online-compression-tool-compares-packer-jsmin-dojo-and-yui-compressor.html
http://www.askapache.com/online-tools/js-compress/
Good Luck!