diff --git a/view-webapp/src/main/webapp/js/domhelper.js b/view-webapp/src/main/webapp/js/domhelper.js
index 148954f..e2c54d8 100644
--- a/view-webapp/src/main/webapp/js/domhelper.js
+++ b/view-webapp/src/main/webapp/js/domhelper.js
@@ -47,6 +47,7 @@ Element.prototype.toggleClass = function(className) {
   return this;
 }
 NodeList.prototype.hasClass = function(className) {
+  if (this.length === 0) return false;
   return this.item(0).classList.contains(className);
 }
 Element.prototype.hasClass = function(className) {