use the length of a filtered array rather than keep a running count

todo-example/dojo/js/todo/model/TodoModel.js

@@ -88,13 +88,9 @@ define(["dojo/_base/declare", "dojox/mvc/StatefulModel", "todo/store/LocalStorag
          * cause the bound "complete" value to be updated as well.
          */
         updateTotalItemsLeft: function () {
-            var remaining = 0;
-
-            array.forEach(this.todos, function (item) {
-                item && !item.isDone.value && remaining++;
-            });
-
-            this.incomplete.set("value", remaining);
+            this.incomplete.set("value", array.filter(this.todos, function (item) {
+                return item && !item.isDone.value;
+            }).length);
         }
     });
 });