evented.js

var Evented = {
  Event: {
    on: function(event, callback, context) {
      this.hasOwnProperty('events') || (this.events = {});
      this.events.hasOwnProperty(event) || (this.events[event] = []);
      this.events[event].push([callback, context]);
    },
    trigger: function(event) {
      var tail = Array.prototype.slice.call(arguments, 1),
          callbacks = this.events[event];
      for(var i = 0, l = callbacks.length; i < l; i++) {
        var callback = callbacks[i][0],
            context = callbacks[i][1] === undefined ? this : callbacks[i][1];
        callback.apply(context, tail);
      }
    }
  },
  extend: function(other) {
    for (var property in this.Event) {
      other[property] = this.Event[property];
    }
    return other;
  }
};

exports.Evented = Evented;