如何在jquery ui Datepicker中将日期时间设置为默认值

<script type="text/javascript" language="javascript">
    $(document).ready(function () {
        $(function () {
            $(".datepicker").datepicker({
                dateFormat: "mm/dd/yy",
                changeMonth: true,
                changeYear: true
            });
        });
    });
</script>
<script type="text/javascript" language="javasc