jQuery UI datepicker:如何更改下拉列表中从短名称到长名称的月份名称？

$(function() {
    $("#datepicker").datepicker({
        dateFormat: "MM yy",
        monthNames: ["January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December"],
        onSelect: function(dateText, inst) {
            var month = $("#ui-datepicker-div .ui-datepicker-month :selected").val();
            var year = $("#ui-datepicker-div .ui-datepicker-year :selected").val();
            $(this).datepicker("option", "monthNames", ["January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December"]);
            $(this).datepicker("update", year + " " + month);
        }
    });
});