Insertion Sort: sorting algorithm

insertionSort.js

/**
 * Insertion sort:
 * Big O notation of O(n^2) due to the double loop
 */
const insertionSort = (items) => {
  /**
   * 1. Loop through array of unsorted items
   * 2. Grab the value of the current iteration index
   * 3. Initialize j index for a second loop back through the sorted section
   * 4. Loop back and compare the last item in the sorted section with the   
   *    current item in iteration of the first loop
   * 5. When each item in the sorted section from the last item > current item in 
   *    iteration of the first loop we insert into position of the current item in 
   *    iteration of the second loop
   * 6. We set as the final value for when there's no item in the sorted section 
   *    > current item in iteration of the first loop
   */

  for (let i = 0; i < items.length; i++) {
    let value = items[i];
    let j = 0;
    for (j = i - 1; j > -1 && items[j] > value; j--) {
      items[j + 1] = items[j];
    }
    items[j+1] = value;
  }
  return items;
}

const unsortedList = [2,10,23,13,23,5,1,6,8,9,3,7,4,3,7,9,30,15,21,22,17,4,5];
const sortedList = insertionSort(unsortedList);

console.log(sortedList) // [ 1, 2, 3, 3, 4, 4, 5, 5, 6, 7, 7, 8, 9, 9, 10, 13, 15, 17, 21, 22, 23, 23, 30 ]