Event handler

add_event

var add_event = function (object, event, callback) {
  object = get_element(object);
  if (!object) {
    return;
  }
  
  if (object && object.addEventListener) {
    object.addEventListener(event, callback, false);
  }
  
  if (object && object.attachEvent) {
    object.attachEvent('on' + event, callback);
  }
};