Nodejs Utililty Methods Array Insertion Sort

"use strict";
Array.prototype.insertionSort = function() {
  for (var key = 1; key < this.length; key++) {
    for (var swap_key = key; this[swap_key] < this[swap_key - 1]; swap_key--) {
      var temp = this[swap_key];
      this[swap_key] = this[swap_key - 1];
      this[swap_key - 1] = temp;
};
var assert = function(expression, name) {
  if ( ! expression) {
    console.log('** Assertion failed', name || '')
var a1 = [5,4,3,6,7,1,2,8,9];
a1.insertionSort();
console.log(a1);
assert(a1.toString() === [1,2,3,4,5,6,7,8,9].toString(), 'Test it is sorted');

Array.prototype.insertionSort = function () {
    for (var i = 1; i < this.length; i++) {
        var j = i, value = this[i];
        while(j > 0 && value < this[j-1]){
            this[j] = this[j-1];
            j--;
        this[j] = value;
};

Array.prototype.insertionSort = function(desc) {
  let A = Object.assign([], this)
  for(let j = 1; j < A.length; j++) {
    let key = A[j]
    let i = j - 1
    while(i >= 0 && (desc ? A[i] < key : A[i] > key)) {
      A[i + 1] = A[i]
      i = i - 1
    A[i + 1] = key
  return A
let arr = [3, 8, 1, 6, 5, 4, 9, 2, 7]
let ascending = arr.insertionSort() 
let descending = arr.insertionSort(true) 
Array.prototype.selectionSort = function(desc) {
  let A = Object.assign([], this)
  for(let j = 0; j < A.length; j++) {
    let key = A[j]
    let m = j
    for(let i = j; i < A.length; i++) {
      m = (desc ? A[i] > A[m] : A[i] < A[m]) ? i : m
    A[j] = A[m]
    A[m] = key
  return A
let arr = [3, 8, 1, 6, 5, 4, 9, 2, 7]
let ascending = arr.selectionSort() 
let descending = arr.selectionSort(true) 

Array.prototype.sort = function(){
  console.log("Please don't use the built in sort function.")
function insertionSort (array) {
  let current, i, j;
  for (i in array) {
    current = array[i];
    for (j=i-1; j>-1 && (array[j] > current); j--) {
      array[j+1] = array[j];
...

'use strict';
Array.prototype.swap = function swap (a, b) {
  const temp = this[a];
  this[a] = this[b];
  this[b] = temp;
};
function insertion_sort (arr) {
  for (let i = 0; i < arr.length; i++) {
    let j = i;
...