Nodejs Utililty Methods Array Multiply

Array.prototype.mul = function(value) {
  var newArray = new Array();
  for(var i=0; i<this.length; i++) {
    newArray[i] = this[i] * value;
    return newArray;

Array.prototype.mult = function(other) {
    if(isFinite(other))  
        other = new Array(this.length).fill(other);
    else
        console.assert(this.length == other.length, 'mult: len(a) != len(b)');
    var ret = new Array(this.length);
    for(var i = 0; i < ret.length; i++)
        ret[i] = this[i] * other[i];
    return ret;
...

Array.prototype.mult2 = function() {
    for (var i = 0; i < this.length; i++) {
        this[i] = this[i] * 2;
};

Array.prototype.multipleConcat = function() {
    var initialArray = arguments[0];
    if (arguments.length > 0) {
      for (var i = 1, arrayCount = arguments.length; i < arrayCount; i++ ) {
        initialArray.push.apply(initialArray, arguments[i]);
      return initialArray;
};
...

Array.prototype.multiples = function(multiple) {
  var multiples = [];
  for (var i = 0; i < this.length; i++){
    multiples.push(this[i] * multiple);
  return multiples;
console.log([1,2,3,4,5].multiples(5));
Array.prototype.myEach = function(someFunction){
...

Array.prototype.multiply = function(a2) {
  var l1 = this.length;
  var l2 = a2.length;
  var len = (l1 < l2 ? l1 : l2);
  var result = new Array(len);
  for (var i = 0; i < len; i++) {
    result[i] = this[i] * a2[i];
  return result;
...

Array.prototype.multiply = function(n){
  results = []
  for (var i = 0; i < this.length; i++){
    for (var j = 0; j < n; j++){
      results.push(this[i])
  return results

Array.prototype.multiplyByTwo = function() {
  var newArr = [];
  for (var i = 0; i < this.length; i++) {
    newArr.push(this[i] * 2)
  return newArr;
};
console.log([1, 2, 3].multiplyByTwo());
Array.prototype.myEach = function(func) {
...

Array.prototype.multislice = function(ranges) {
  if(typeof ranges === 'undefined')
    throw Exception("Ranges have to be defined!");
  if(typeof ranges !== 'object') 
    throw Exception("You have to pass an array!");
  return ranges.map(el => this.slice(el.from, el.to));
};

'use strict';
var _typeof = typeof Symbol === "function" && typeof Symbol.iterator === "symbol" ? function (obj) { 
  return typeof obj; 
  } : function (obj) { return obj && typeof Symbol === "function" && obj.constructor === Symbol ? "symbol" : typeof obj; };
Array.prototype.multislice = function (ranges) {
  var _this = this;
  if (typeof ranges === 'undefined') throw Exception("Ranges have to be defined!");
  if ((typeof ranges === 'undefined' ? 'undefined' : _typeof(ranges)) !== 'object') throw Exception("You have to pass an array!");
  return ranges.map(function (el) {
...