diff --git a/static/skin/index.js b/static/skin/index.js
index a0f5441fd..10f49a134 100644
--- a/static/skin/index.js
+++ b/static/skin/index.js
@@ -1,4 +1,4 @@
-(function() {
+const kiwixServe = (function() {
     const root = document.querySelector(`link[type='root']`).getAttribute('href');
     const incrementalLoadingParams = {
         start: 0,
@@ -493,5 +493,8 @@
         }
         setCookie(filterCookieName, params.toString());
     }
+    return {
+        updateBookCount
+    }
 })();