diff --git a/chapter-04/01-basic-mesh-material.html b/chapter-04/01-basic-mesh-material.html
index 2a371730..f07b49e7 100644
--- a/chapter-04/01-basic-mesh-material.html
+++ b/chapter-04/01-basic-mesh-material.html
@@ -124,11 +124,13 @@
             this.switchRenderer = function () {
                 if (renderer instanceof THREE.WebGLRenderer) {
                     renderer = canvasRenderer;
-                    document.getElementById("WebGL-output").empty();
+                   // document.getElementById("WebGL-output").empty();
+                   $("#WebGL-output").empty();
                     document.getElementById("WebGL-output").appendChild(renderer.domElement);
                 } else {
                     renderer = webGLRenderer;
-                    document.getElementById("WebGL-output").empty();
+                   // document.getElementById("WebGL-output").empty();
+                   $("#WebGL-output").empty();
                     document.getElementById("WebGL-output").appendChild(renderer.domElement);
                 }
             }
@@ -237,4 +239,4 @@
     window.onload = init;
 </script>
 </body>
-</html>
\ No newline at end of file
+</html>