CoffeeScript is clean, but the generated JS is...generated.

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.generated.js

var __slice = [].slice;

this.events = {
  events: {},
  on: function(topic, handler, context) {
    var _base;
    if (context == null) {
      context = this;
    }
    return ((_base = this.events)[topic] || (_base[topic] = [])).push({
      handler: handler,
      context: context
    });
  },
  trigger: function() {
    var args, context, handler, topic, _i, _len, _ref, _ref1, _results;
    topic = arguments[0], args = 2 <= arguments.length ? __slice.call(arguments, 1) : [];
    if (this.events[topic] == null) {
      return;
    }
    _ref = this.events[topic];
    _results = [];
    for (_i = 0, _len = _ref.length; _i < _len; _i++) {
      _ref1 = _ref[_i], handler = _ref1.handler, context = _ref1.context;
      _results.push(handler.apply(context, args));
    }
    return _results;
  }
};

events.original.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);

True , the generated javascript is harder to read, i call it the "babylon" effect , like the tower in the first testament. But it is still readable.However there is no 1 to 1 coffee - js translation so , though the cs is compact , i would not have gone for such an extreme "optimisation".