Merge sort

Author: highflyer910

mergesort.js

@@ -0,0 +1,22 @@
+function mergeSort (arr) {    
+    if (arr.length < 2) return arr;
+    var middleIndex = Math.floor(arr.length / 2);
+    var firstHalf = arr.slice(0, middleIndex);
+    var secondHalf = arr.slice(middleIndex);
+    
+    return merge(mergeSort(firstHalf), mergeSort(secondHalf));
+}
+ 
+function merge (array1, array2) { 
+    var result = [];
+    while (array1.length && array2.length) {
+      var minElem;
+      if (array1[0] < array2[0]) minElem = array1.shift();
+      else minElem = array2.shift();
+      result.push(minElem);
+    }
+    
+    if (array1.length) result = result.concat(array1);
+    else result =result.concat(array2);
+    return result;
+}