diff --git a/pyleds/templates/index.html b/pyleds/templates/index.html
index a73790d..e68d188 100644
--- a/pyleds/templates/index.html
+++ b/pyleds/templates/index.html
@@ -7,11 +7,16 @@
     <link rel="stylesheet" href="custom.css">
 
     <script type="text/javascript">
-        const hexToRgb = hex =>
-            hex.replace(/^#?([a-f\d])([a-f\d])([a-f\d])$/i
-                ,(m, r, g, b) => '#' + r + r + g + g + b + b)
-                .substring(1).match(/.{2}/g)
-                .map(x => parseInt(x, 16));
+        'use strict';
+        function hexToRgb(value) {
+            var aRgbHex = value.substring(1).match(/.{1,2}/g);
+            var aRgb = [
+                parseInt(aRgbHex[0], 16),
+                parseInt(aRgbHex[1], 16),
+                parseInt(aRgbHex[2], 16)
+            ];
+            return aRgb;
+        }
 
         function show_loading(visible) {
             document.getElementById('loading').style.visibility = visible ? 'visible' : 'hidden';
@@ -51,7 +56,7 @@
             document.getElementById('tempo').value = status.features.tempo.bpm;
             let regions = status.features.region;
             let regLen = regions.length;
-            for(i = 0; i < regLen; i++) {
+            for(let i = 0; i < regLen; i++) {
                 if (regions[i]) {
                     document.getElementById('region_' + i).classList.remove('region_off');
                 } else {