diff --git a/sorting-algorithms-in-javascript/shellsort-counters.js b/sorting-algorithms-in-javascript/shellsort-counters.js
index efc1227..00b887d 100644
--- a/sorting-algorithms-in-javascript/shellsort-counters.js
+++ b/sorting-algorithms-in-javascript/shellsort-counters.js
@@ -1,22 +1,22 @@
 // sample of arrays to sort
-var arrayRandom = [9, 2, 5, 6, 4, 3, 7, 10, 1, 8];
-var arrayOrdered = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
-var arrayReversed = [10, 9, 8, 7, 6, 5, 4, 3, 2, 1];
+let arrayRandom = [9, 2, 5, 6, 4, 3, 7, 10, 1, 8];
+let arrayOrdered = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
+let arrayReversed = [10, 9, 8, 7, 6, 5, 4, 3, 2, 1];
 
 // gaps
-var gaps = [701, 301, 132, 57, 23, 10, 4, 1];
+let gaps = [701, 301, 132, 57, 23, 10, 4, 1];
 
 function shellsort(array) {
-  var countOuter = 0;
-  var countInner = 0;
-  var countSwap = 0;
+  let countOuter = 0;
+  let countInner = 0;
+  let countSwap = 0;
 
-  for(var g = 0; g < gaps.length; g++) {
-    var gap = gaps[g];
-    for(var i = gap; i < array.length; i++) {
+  for(let g = 0; g < gaps.length; g++) {
+    let gap = gaps[g];
+    for(let i = gap; i < array.length; i++) {
       countOuter++;
-      var temp = array[i];
-      for(var j = i; j >= gap && array[j - gap] > temp; j -= gap) {
+      let temp = array[i];
+      for(let j = i; j >= gap && array[j - gap] > temp; j -= gap) {
         countInner++;
         countSwap++;
         array[j] = array[j - gap];