events.coffee

events =

  events: {}

  bind: (topic, handler, context = this) ->
    (@events[topic] ||= []).push { handler, context }

  trigger: (topic, args...) ->
    if @events[topic]?
      event.handler.apply event.context, args for event in @events[topic]

events.js

var slice = Array.prototype.slice;

var events = {

  events: {},

  bind: function (topic, handler, context) {
    if (context == null) context = this;
    this.events[topic] = this.events[topic] || []
    this.events[topic].push({ handler: handler, context: context });
  },

  trigger: function (topic/*, args...*/) {
    if (this.events[topic] == null) return;
    var args = slice.apply(arguments, 1);
    for (var i = 0, l = this.events[topic].length, event; i < l; i++) {
      event = this.events[topic][i];
      event.handler.apply(event.context, args);
    }
  }
};

// just for comparison, that's the JS I'd hand write
// Not terribly difficult, but sure has a lot of "stuff"

usage.coffee

# use as singleton
events.bind 'foo', (a, two) -> console.log a, two
events.trigger 'foo', 'a', 2

# mixin to other objects assuming a merge/extend function
merge SomeClass.prototype, events
instance = new SomeClass()
instance.bind 'foo', -> console.log 'hi'
instance.trigger 'foo'