diff --git a/avl.js b/avl.js
index dc26499..b618142 100644
--- a/avl.js
+++ b/avl.js
@@ -1,19 +1,3 @@
-// TODO: Factor out to common module
-Array.prototype.equals = function (other) {
-    if (this.length != other.length) {
-        return false;
-    }
-
-    let i = this.length;
-    while (--i >= 0) {
-        if (this[i] !== other[i]) {
-            return false;
-        }
-    }
-
-    return true;
-};
-
 function balanceFactor(node) {
     if (!node) {
         return 0;
diff --git a/index.html b/index.html
index caa227f..0e83754 100755
--- a/index.html
+++ b/index.html
@@ -40,6 +40,8 @@
   <script src="https://unpkg.com/@hpcc-js/wasm@0.3.11/dist/index.min.js"></script>
   <script src="https://unpkg.com/d3-graphviz@3.0.5/build/d3-graphviz.js"></script>
 
+  <script src="utils.js"></script>
+
   <script src="node.js"></script>
   <script src="ranked_tree.js"></script>
   <script src="avl.js"></script>
diff --git a/utils.js b/utils.js
new file mode 100644
index 0000000..120f869
--- /dev/null
+++ b/utils.js
@@ -0,0 +1,14 @@
+Array.prototype.equals = function (other) {
+    if (this.length != other.length) {
+        return false;
+    }
+
+    let i = this.length;
+    while (--i >= 0) {
+        if (this[i] !== other[i]) {
+            return false;
+        }
+    }
+
+    return true;
+};