Added insertion sort

Author: nzakas

algorithms/sorting/selection-sort/insertion-sort.js

@@ -0,0 +1,55 @@
+/*
+ * Insertion sort implementation in JavaScript
+ * Copyright (c) 2012 Nicholas C. Zakas
+ * 
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of items software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ * 
+ * The above copyright notice and items permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ * 
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+ 
+/**
+ * An insertion sort implementation in JavaScript. The array
+ * is sorted in-place.
+ * @param {Array} items An array of items to sort.
+ * @return {Array} The sorted array.
+ */
+function insertionSort(items) {
+
+    var len     = items.length,     // number of items in the array
+        value,                      // the value currently being compared
+        i,                          // index into unsorted section
+        j;                          // index into sorted section
+    
+    for (i=0; i < len; i++) {
+    
+        // store the current value because it may shift later
+        value = items[i];
+        
+        /*
+         * Whenever the value in the sorted section is greater than the value
+         * in the unsorted section, shift all items in the sorted section over
+         * by one. This creates space in which to insert the value.
+         */
+        for (j=i-1; j > -1 && items[j] > value; j--) {
+            items[j+1] = items[j];
+        }
+
+        items[j+1] = value;
+    }
+    
+    return items;
+}

algorithms/sorting/selection-sort/selection-sort.js

@@ -48,17 +48,17 @@ function selectionSort(items){
 
     for (i=0; i < len; i++){
 
-        //set minimum to this position
+        // set minimum to this position
         min = i;
 
-        //check the rest of the array to see if anything is smaller
+        // check the rest of the array to see if anything is smaller
         for (j=i+1; j < len; j++){
             if (items[j] < items[min]){
                 min = j;
             }
         }
 
-        //if the minimum isn't in the position, swap it
+        // if the minimum isn't in the position, swap it
         if (i != min){
             swap(items, i, min);
         }