I maintain a JS frontend library.
To get going I wrote it in Rails, as that's what I know. It works quite well if you have Rails installed, but it's a pretty silly way to work for anyone else.
What's a "best practice" way to organize a frontend JS library written in CoffeeScript on Github?
There needs to be simple ways to
build a compressed compiled release version from a set of CoffeeScript files.
run a fresh version in the browser during development
run a test suite
i am not sure whether my suggestion will answer your question or not.
my suggestion are
then integrate tasks above to ci tool, e.g., jenkins to automate them
your jenkins job will do these task step by step