perfect: improve browser compatibility

1 files changed, 5 insertions, 1 deletions

diff --git a/_includes/sidebar/article-menu.html b/_includes/sidebar/article-menu.html
index 2e273de..3e618ff 100644
--- a/_includes/sidebar/article-menu.html
+++ b/_includes/sidebar/article-menu.html
@@ -36,9 +36,13 @@
     // The header element
     var header = document.querySelector('header.site-header');
 
-    function doMenuCollapse(index, over_items=20) {
+    function doMenuCollapse(index, over_items) {
       var items = menuContent.firstChild.children;
 
+      if (over_items == undefined) {
+        over_items = 20;
+      }
+
       if (items.length < over_items) {
         return;
       }