jQuery UI Datepicker - Date Format | Date formating option for jQuery UI Date Picker

$( "#datepicker" ).datepicker( "option", "dateFormat", "mm/dd/yy");
$( "#datepicker" ).datepicker( "option", "dateFormat", "yy-mm-dd");
$( "#datepicker" ).datepicker( "option", "dateFormat", "d MM, y");
$( "#datepicker" ).datepicker( "option", "dateFormat", "DD, d MM, yy");
$( "#datepicker" ).datepicker( "option", "dateFormat", "d M, y");
$( "#datepicker" ).datepicker( "option", "dateFormat", "'day' d 'of' MM 'in the year' yy");

//if Above not work than you may also try below date formate option for jquery ui datetimepicker script
 jQuery("#txt_holiday_date").datepicker({dateFormat: 'yy-mm-dd'});