diff --git a/think.greaterchiangmai.com/public/js/main.js b/think.greaterchiangmai.com/public/js/main.js
index a92e608..8854dfd 100644
--- a/think.greaterchiangmai.com/public/js/main.js
+++ b/think.greaterchiangmai.com/public/js/main.js
@@ -43,9 +43,13 @@
         scrollPos = scrollPos + 60;
         menu_links.each(function () {
             var currLink = $(this);
-            var hasPos = currLink.attr("href").indexOf("#");
+            var href = currLink.attr("href");
+            if (!href) {
+                return;
+            }
+            var hasPos = href.indexOf("#");
             if (hasPos > -1) {
-                var res = currLink.attr("href").substring(hasPos);
+                var res = href.substring(hasPos);
                 if (res != '' && res != '#' && $(res).length > 0) {
                     var refElement = $(res);
                     if (refElement.offset().top <= scrollPos && refElement.offset().top + refElement.height() > scrollPos) {