ryandabler

// Create "backend" object to hold data for getters and setters on main object
const _ = Object.create( null );

Object.defineProperties(
    _,
    {
        firstname: {
            value: 'John',
            writable: true,
            enumerable: false,

jeffchao

// Run using jasmine-node.
//   e.g.: jasmine-node file_name.spec.js

Array.prototype.mymap = function (callback) {
  var obj = Object(this);

  if (obj.length === 0) return null;
  if (typeof(callback) === 'undefined') return null;

  for (var i = 0, o; o = obj[i]; i++) {