change shuffling function

server/modules/GameManager.js

@@ -379,7 +379,7 @@ function initializePeopleForGame (uniqueCards, moderator) {
         }
     }
 
-    cards = shuffleArray(cards); // The deck should probably be shuffled, ey?.
+    cards = shuffle(cards); // The deck should probably be shuffled, ey?.
 
     let j = 0;
     if (moderator.userType === globals.USER_TYPES.TEMPORARY_MODERATOR) { // temporary moderators should be dealt in.
@@ -410,13 +410,20 @@ function initializePeopleForGame (uniqueCards, moderator) {
     return people;
 }
 
-function shuffleArray (array) {
-    for (let i = 0; i < array.length; i ++) {
-        const randIndex = Math.floor(Math.random() * i);
-        const temp = array[i];
-        array[i] = array[randIndex];
-        array[randIndex] = temp;
+/*
+-- To shuffle an array a of n elements (indices 0..n-1):
+for i from n−1 downto 1 do
+     j ← random integer such that 0 ≤ j ≤ i
+     exchange a[j] and a[i]
+ */
+function shuffle(array) {
+    for (let i = array.length - 1; i > 0; i --) {
+        const j = Math.floor(Math.random() * (i + 1));
+        const temp = array[j];
+        array[j] = array[i];
+        array[i] = temp;
     }
+
     return array;
 }