Updated bubble sort implementations

Author: Nicholas C. Zakas

algorithms/sorting/bubble-sort/bubble-sort-2.js

@@ -0,0 +1,41 @@
+/*
+ * Bubble sort implementation in JavaScript
+ * Copyright (c) 2009 Nicholas C. Zakas
+ * MIT Licensed - see LICENSE for details on license.
+ */
+ 
+
+/**
+ * Swaps two values in an array.
+ * @param {Array} items The array containing the items.
+ * @param {int} firstIndex Index of first item to swap.
+ * @param {int} secondIndex Index of second item to swap.
+ * @return {void}
+ */
+function swap(items, firstIndex, secondIndex){
+    var temp = items[firstIndex];
+    items[firstIndex] = items[secondIndex];
+    items[secondIndex] = temp;
+}
+ 
+/**
+ * A bubble sort implementation in JavaScript. The array
+ * is sorted in-place. This uses two reversed loops that
+ * count down instead of counting up.
+ * @param {Array} items An array of items to sort.
+ * @return {Array} The sorted array.
+ */
+function bubbleSort(items){
+    var len = items.length,
+        i, j;
+
+    for (i=len-1; i >= 0; i--){
+        for (j=len-i; j >= 0; j--){
+            if (items[j] < items[j-1]){
+                swap(items, j, j-1);
+            }
+        }
+    }
+    
+    return items;
+}

algorithms/sorting/bubble-sort/bubble-sort.js

@@ -25,13 +25,17 @@ function swap(items, firstIndex, secondIndex){
  * @return {Array} The sorted array.
  */
 function bubbleSort(items){
-    for (var i=items.length-1; i >= 0; i--){
-        for (var j=i; j >= 0; j--){
-            if (items[j] < items[j-1]){
-                swap(items, j, j-1);
+
+    var len = items.length,
+        i, j, stop;
+
+    for (i=0; i < len; i++){
+        for (j=0, stop=len-i; j < stop; j++){
+            if (items[j] > items[j+1]){
+                swap(items, j, j+1);
             }
         }
     }
 
     return items;
-}
+}