Javascript Algorithm Array Sort Insertion Sort 2

var arr = [5, 2, 4, 6, 1, 3];
console.log(arr);// ww  w .  j  ava 2 s .co  m
console.log(insertion_sort(arr));

function insertion_sort(array) {
    for(var i = 1; i < array.length; i++) {
        var key = array[i];
        var j = i - 1;
        while(j >= 0 && array[j] > key) {
            array[j + 1] = array[j];
            j--;
        }
        array[j + 1] = key;
    }
    return array;
}

function insertionSort(arr, comparator) {
  if (!comparator) {
    comparator = (a, b) => a < b;/*from  w w  w  . java 2 s .  c  o  m*/
  }
  let current;
  for (let i = 1; i < arr.length; i++) {
    current = i;
    while(current > 0 && comparator(arr[current], arr[current-1])) {
      swap(current, current-1, arr);
      current--;
    }
  }
  return arr;
}

function swap(i, j, arr) {
  let temp = arr[i];
  arr[i] = arr[j];
  arr[j] = temp;
  return arr;
}

let nums = [5, 4, 3, 2, 1, 6, 8, 9, 7];
insertionSort(nums, (a, b) => a > b);
console.log(nums);