diff --git a/public/js/extra.js b/public/js/extra.js
index 499bdc4cc..bc6092db2 100644
--- a/public/js/extra.js
+++ b/public/js/extra.js
@@ -1115,6 +1115,7 @@ module.exports = {
   renderTitle: renderTitle,
   renderFilename: renderFilename,
   renderTags: renderTags,
+  isValidURL: isValidURL,
   generateToc: generateToc,
   smoothHashScroll: smoothHashScroll,
   scrollToHash: scrollToHash,
diff --git a/public/js/index.js b/public/js/index.js
index 1ba10e14f..77ab089c0 100644
--- a/public/js/index.js
+++ b/public/js/index.js
@@ -36,6 +36,7 @@ var renderTOC = extra.renderTOC;
 var renderTitle = extra.renderTitle;
 var renderFilename = extra.renderFilename;
 var renderTags = extra.renderTags;
+var isValidURL = extra.isValidURL;
 var scrollToHash = extra.scrollToHash;
 var updateLastChangeUser = extra.updateLastChangeUser;
 var updateOwner = extra.updateOwner;