.datepicker(‘setdate’) issues, in jQuery

When you trying to call setDate you must provide valid javascript Date object.

queryDate="2009-11-01";

var parsedDate = $.datepicker.parseDate('yy-mm-dd', queryDate);

$('#datePicker').datepicker('setDate', parsedDate);

This will allow you to use different formats for query date and string date representation in datepicker. This approach is very helpful when you create multilingual site. Another helpful function is formatDate, which formats javascript date object to string.

$.datepicker.formatDate( format, date, settings );