Date picker in JQuery change formet

<link rel="stylesheet" href="http://code.jquery.com/ui/1.10.3/themes/smoothness/jquery-ui.css">
  <script src="http://code.jquery.com/jquery-1.9.1.js"></script>
  <script src="http://code.jquery.com/ui/1.10.3/jquery-ui.js"></script>

  <script>
  $(function() {
    $( "#tabs" ).tabs();
  });
  </script>
  <script>
  $(function() {
    $( ".datepicker" ).datepicker();
      $( "#format" ).click(function() {
            $.datepicker._defaults.dateFormat = "yy-mm-dd";
          $( "#datepicker" ).datepicker( "option", "dateFormat", $( this ).val() );
      });
  });
  </script>