Fix custom js

kiwix · Jun 21, 2024 · dae334f · dae334f
1 parent 1e3f9ce
commit dae334f
Showing 1 changed file with 4 additions and 1 deletion.
diff --git a/Support/injection.js b/Support/injection.js
@@ -31,7 +31,10 @@ let observer = new IntersectionObserver(function(entries) {
 // register scroll view to handle heading on top of the page
 window.onscroll = function() {
 	if (document.documentElement.scrollTop <= 0) {
-		window.webkit.messageHandlers.headingVisible.postMessage({id: headings[0].id})
+        const headingVisible = window.webkit.messageHandlers.headingVisible
+        if(headingVisible !== undefined && headingVisible.postMessage !== undefined) {
+            headingVisible.postMessage({id: headings[0].id})
+        }
 	}
 }