code: function(id, offset, period) {
  		var target = $(id),
  			inst = this._getInst(target[0]);
  
  		if (this._isDisabledDatepicker(target[0])) {
  			return;
  		}
  		this._adjustInstDate(inst, offset +
  			(period === "M" ? this._get(inst, "showCurrentAtPos") : 0), // undo positioning
  			period);
  		this._updateDatepicker(inst);
  	}
docs: /* Adjust one of the date sub-fields.