Bare bones event system

dispatcher.coffee

dispatcher = {}

dispatcher._subscribers = {}

dispatcher.on = (eventName, callback, context) ->
  (dispatcher._subscribers[eventName] or = [])
    .push {
      callback: callback
      context: context
    }
  return ->
    dispatcher.off eventName, callback, context
    return

dispatcher.off = (eventName, callback, context) ->
  subscribers = dispatcher._subscribers[eventName]
  if subscribers
    i = subscribers.length
    while i--
      s = subscribers[i]
      if s.callback is callback and s.context is context
        subscribers.splice i, 1
  return

dispatcher.trigger = (eventName, args...) ->
  subscribers = dispatcher._subscribers[eventName]
  if subscribers
    for s in subscribers
      s.callback.apply s.context, args
  return