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);

It would be better to add return statement, so methods will return nothing. If we add undefined or null the methods will contain return undefined or return null in their JavaScript presentation.

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 :)