Experimenting with JavaScript's custom event model

customEvent_ex.js

function EventDispatcher() {
  this._listeners = {};
}

EventDispatcher.prototype = {
  constructor: EventDispatcher,
  addEventListener: function (type, listener) {
    if ( typeof this._listeners[type] == "undefined" ) {
      this._listeners[type] = [];
    }
    this._listeners[type].push(listener);
  },
  
  dispatchEvent: function(event) {
    if (typeof event == "string"){
     event = { type: event };
    }
    if (!event.target){
     event.target = this;
    }

    if (!event.type){ 
      throw new Error("Event object missing 'type' property.");
    }

    if (this._listeners[event.type] instanceof Array){
     var listeners = this._listeners[event.type];
     for (var i=0, len=listeners.length; i < len; i++){
       listeners[i].call(this, event);
     }
    }
  }
};

Projects.prototype = new EventDispatcher();
Projects.prototype.constructor = Projects;

function Projects() {
  EventDispatcher.call(this);
  this._list = [];
};

Projects.prototype.load = function() {
  var that = this;
  function build_list(data, parent) {
    var value = eval(data);
    for ( index in value ) {
      var project = new Object();
      project.name = value[index].fields.name;
      project.archived = value[index].fields.archived;
      project.visible = value[index].fields.visible;
      project.file_path_0 = value[index].fields.file_path_0;
      project.file_path_1 = value[index].fields.file_path_1;
      project.file_path_2 = value[index].fields.file_path_2;
      project.file_path_3 = value[index].fields.file_path_3;
      project.file_path_4 = value[index].fields.file_path_4;
      project.file_path_5 = value[index].fields.file_path_5;
      project.file_path_6 = value[index].fields.file_path_6;
      project.file_path_7 = value[index].fields.file_path_7;
      project.file_path_8 = value[index].fields.file_path_8;
      project.file_path_9 = value[index].fields.file_path_9;
      parent._list.push(project);
    } // end for
    
    parent.dispatchEvent("data_loaded");
  };

  $.get("/html/portfolio/", function(data) {
    build_list(data, that);
    // displatch data loaded event.
  });
};

Projects.prototype.get_archives = function() {
  _archive = {};
  for ( var i = 0; i < this._list.length; i++ ) {
    if ( this._list[i].name == "ARCHIVES" ) {
      _archive = this._list[i];
    }
  }
 return _archive;
};

Projects.prototype.get_active_projects = function() {
  _active_p = [];
  for ( var i = 0; i < this._list.length; i++ ) {
    if ( this._list[i].visible == true ) {
      _active_p.push(this._list[i]);
    }
  }
  return _active_p;
};

// End result
var p = new Projects();
p.load();
p.addEventListener("data_loaded", function(e) {
  alert(e.target.get_archives().name);
});