update js to add/remove selected class

booking.js

@@ -6,7 +6,13 @@ Drupal.ajax.prototype.commands.bookingAjaxCheckboxes =  function(ajax, response,
         var arr = $.parseJSON($('input#' + response.formDataElement).val())
         $('#' + response.formName).find(':checkbox[name^="' + response.checkboxName + '"]').each(function () {
             //.prop() doesn't exist in Drupal's old version of jQuery so use .attr() instead
-            $(this).attr("checked", ($.inArray($(this).val(), arr) != -1));
+            if ($.inArray($(this).val(), arr) != -1) {
+                $(this).attr("checked", "true");
+                $(this).addClass("selected");
+            } else {
+                $(this).attr("checked", "false");
+                $(this).removeClass("selected");
+            }
         });
     });
 }