How to namespace in CoffeeScript

namespace.coffee

# Node.js is exports; Rails is window
global = if typeof exports isnt 'undefined' then exports else window

global.namespace = (target, name, block) ->
  [target, name, block] = [global, arguments...] if arguments.length < 3
  top    = target
  target = target[item] or= {} for item in name.split '.'
  block target, top

# Declare your class
namespace "NS", (global) ->
  class global.HtmlCanvas
  
# Use your class
NS.HtmlCanvas()