gem install nibjs
nibjs --help 

mylib/
  dist/
  lib/
    Foo.[js,coffee]          # exports.Foo = ...
    Bar.[js,coffee]          # require('./Foo')
    index.[js,coffee]        # exports.X = ...
  spec/
    foo_spec.[js,coffee]
    bar_spec.[js,coffee]
  package.json

# if the sources are .js
nibjs --libname=mylib --output=dist/mylib.js lib
# if the sources are .coffee
nibjs --coffee --libname=mylib --output=dist/mylib.js lib

<script src="js/nibjs.js" type="text/javascript">
<script src="js/mylib.js" type="text/javascript">
<script>
  // mylib contains what index.[js,coffee] exports
  var mylib = NibJS.require('mylib')
</script>

nibjs --coffee --no-coffee-compile --libname=mylib --output=dist/mylib.coffee lib

<script src="js/coffee-script.js" type="text/javascript">
<script src="js/nibjs.js" type="text/javascript">
<script src="js/mylib.coffee" type="text/coffeescript">
<script>
  /* But be warned of coffeescript's issue 1054
     https://github.com/jashkenas/coffee-script/issues/#issue/1054 */
  var mylib = NibJS.require('mylib')
</script>

nibjs --standalone --libname=mylib --output=dist/mylib.js lib

<script src="js/mylib.js" type="text/coffeescript">
<script>
  // NibJS is itself included in mylib.js
  var mylib = NibJS.require('mylib')
</script>