Set default date format for jQuery UI DatePicker

<script type="text/javascript">
        $(function () {
            $(".date").datepicker({ clickInput: true, dateFormat: 'yy-mm-dd' })({
                showOn: 'button',               
                buttonImageOnly: true,
                buttonImage: 'http://jqueryui.com/demos/datepicker/images/calendar.gif'
            });
        });
     </script>

This code work thanks Azim g