Update custom.js

custom.js

@@ -1,6 +1,30 @@
 $( document ).ready(function() {
+
+var targetedNode = holder[0]
 
-
+	   // Create an observer instance linked to the callback function
+    var observer = new MutationObserver(function(mutationsList, observer) {
+        $(mutationsList).each(function(index, item){
+            if (item.type === 'childList'){
+
+                if (item.addedNodes.length > 0){
+                    alert('new div is being added!');
+                }
+
+                if (item.removedNodes.length > 0){
+                    alert('div has been removed'); 
+                }
+
+            }
+        });
+    });
+
+    // Start observing the target node for configured mutations
+    observer.observe(targetedNode, { 
+        attributes: true, 
+        childList: true, 
+        subtree: true 
+    });