diff --git a/Wasm.Dom/wwwroot/js/JSObject.6.0.1.js b/Wasm.Dom/wwwroot/js/JSObject.6.0.1.js
index 046c126..d53baef 100644
--- a/Wasm.Dom/wwwroot/js/JSObject.6.0.1.js
+++ b/Wasm.Dom/wwwroot/js/JSObject.6.0.1.js
@@ -1,6 +1,7 @@
 window.nkJSObject =
 {
     objectMap: [],
+    emptySlots: [],
     RegisterObject: function(obj)
     {
         if (obj == null)
@@ -8,9 +9,18 @@
         if (nkJSObject.objectMap.indexOf(obj) != -1)
             throw "object already registered";
 
-        nkJSObject.objectMap.push(obj);
-        var uid = nkJSObject.objectMap.indexOf(obj);
-        return uid;
+        if (nkJSObject.emptySlots.length == 0)
+        {
+            nkJSObject.objectMap.push(obj);
+            var uid = nkJSObject.objectMap.lastIndexOf(obj);
+            return uid;
+        }
+        else
+        {
+            var uid = nkJSObject.emptySlots.pop();
+            nkJSObject.objectMap[uid] = obj;
+            return uid;
+        }
     },
     GetObject: function(uid)
     {
@@ -19,6 +29,7 @@
     DisposeObject: function(uid)
     {
         delete nkJSObject.objectMap[uid];
+        nkJSObject.emptySlots.push(uid);
     },
     GetWindow: function()
     {