events.coffee

@events =

  events: {}

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

  trigger: (topic, args...) ->
    return unless @events[topic]?
    handler.apply(context, args) for {handler, context} in @events[topic]

events.js

(function() {

  var slice = Array.prototype.slice;

  this.events = {

    events: {},

    on: 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) {
      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);
      }
    }
  };

}).call(this);

Something like this would be more correct (like source JS code)

@events =

  events: {}

  on: (topic, handler, context = this) ->
    (@events[topic] or= []).push {handler, context}; return

  trigger: (topic, args...) ->
    return unless @events[topic]?
    handler.apply(context, args) for {handler, context} in @events[topic]; return

Yeah, I'm well aware of implicit returns guys; I'd return this if I cared, but don't :)