improve insertion sort

Author: amejiarosario

book/chapters/selection-sort.adoc

@@ -2,7 +2,7 @@
 
 The selection sort is a simple sorting algorithm. As its name indicates, it chooses the lowest element from the list and move it where it should be.
 
-TIP: selection sort is a in-place sorting algorithms, it should be used when auxiliary memory is limited.
+TIP: Selection sort is a in-place sorting algorithms, it should be used when auxiliary memory is limited.
 
 .Selection sort algorithm
 . Start with the element in position 0.
@@ -38,7 +38,7 @@ It uses JavaScript ES6 destructing arrays.
 
 A variable can be assign to its values using the destructing syntax.
 
-[source, js]
+[source, javascript]
 ----
 let a, b;
 
@@ -51,7 +51,7 @@ console.log(b); //️↪️ 2
 
 Two variables values can be swapped in one destructuring expression.
 
-[source, js]
+[source, javascript]
 ----
 [a, b] = [b, a];
 console.log(a); //↪️ 2

src/algorithms/sorting/insertion-sort.js

@@ -11,10 +11,10 @@ const { swap } = require('./sorting-common');
 function insertionSort(collection) {
   const array = Array.from(collection);
 
-  for (let outer = 0; outer < array.length; outer += 1) {
+  for (let outer = 1; outer < array.length; outer++) {
     const insert = array[outer];
 
-    for (let inner = outer - 1; inner >= 0 && array[inner] > insert; inner -= 1) {
+    for (let inner = outer - 1; array[inner] > insert; inner--) {
       swap(array, inner + 1, inner);
     }
   }

src/algorithms/sorting/sorting-common.js

@@ -7,7 +7,8 @@
  * @param {integer} to index of the 2nd element
  */
 function swap(array, from, to) {
-  [array[from], array[to]] = [array[to], array[from]]; // ES6 array destructing
+  // ES6 array destructing
+  [array[from], array[to]] = [array[to], array[from]];
 }
 // end::swap[]