diff --git a/docs/js/extra.js b/docs/js/extra.js
index d0a1e608..928e0662 100644
--- a/docs/js/extra.js
+++ b/docs/js/extra.js
@@ -72,7 +72,7 @@ var nodemcu = nodemcu || {};
     });
 
     // Pass in the target node, as well as the observer options
-    observer.observe(flyOutWrapper, config);
+    observer.observe(flyOutWrapper, observerConfig);
   }
   function createLanguageLinkFor(languageCode, isCurrentlySelected) {
     var strong;