Simple version of Array.prototype.map

fakeMap.js

Array.prototype.fakeMap = function (fn, context) {
  var out = this instanceof Array ? [] : {},
    context = context || this,
    result,
    n;
  if (typeof fn !== "function") {
    return [];
  }
  for (n in this) {
    if (this.hasOwnProperty(n)) {
      result = fn.call(context, this[n]);
      out[n] = result;
    }
  }
  return out;
}

Object.prototype.fakeMap = Array.prototype.fakeMap;