diff --git a/comparator_visualization.js b/comparator_visualization.js
index 4ab014a..3f26b0c 100644
--- a/comparator_visualization.js
+++ b/comparator_visualization.js
@@ -9,8 +9,9 @@ let rRecorder = new Recorder(
     "right"
 ).renderAtOnce();
 
-let left = new AVLTree();
-let right = new WAVLTree();
+let left = null;
+let right = null;
+setTrees(AVLTree, WAVLTree);
 
 function operationCallback(lMethod, rMethod, id) {
     let number = document.getElementById(id).value;
@@ -41,12 +42,7 @@ function deleteCallback() {
     );
 }
 
-function switchTree(TreeType, side) {
-    let [lType, rType] =
-        side == "left"
-            ? [TreeType, right.constructor]
-            : [left.constructor, TreeType];
-
+function setTrees(lType, rType) {
     left = new lType();
     left.recorder = lRecorder;
 
@@ -59,13 +55,19 @@ function switchTree(TreeType, side) {
     }
 }
 
+function switchTree(TreeType, side) {
+    let [lType, rType] =
+        side == "left"
+            ? [TreeType, right.constructor]
+            : [left.constructor, TreeType];
+    setTrees(lType, rType);
+}
+
 async function render() {
     await Promise.all([
         new Promise(() => lRecorder.render()),
         new Promise(() => rRecorder.render()),
     ]);
-    // lRecorder.render();
-    // rRecorder.render();
     setTimeout(render);
 }
 render();