Nodejs Utililty Methods Fibonacci Sequence Get

Number.prototype.iterFib = function () {
  var v1 = 0, v2 = 1, temp = 0;
  (new Array()).rangeArray(0, this-1).forEach(function(index) {
    temp = v2;
    v2 = v2 + v1;
    v1 = temp;
  });
  return v2;

Number.prototype.memoFib = function (hash={}) {
  if (Number(this) < 0) return -1;
  else if (Number(this) === 0) return 0;
  else if (Number(this) === 1) return 1;
  else {
    prevFib = hash[this-1] || (hash[this-1] = (this-1).memoFib(hash));
    prevPrevFib = hash[this-2] || (hash[this-2] = (this-2).memoFib(hash));
    return prevFib + prevPrevFib;

Number.prototype.naiveFib = function () {
  if (Number(this) < 0)
    return -1;
  switch (Number(this)) {
    case 0:
      return 0;
    case 1:
      return 1;
    default:
...

Array.prototype.last = function() {
  return this[this.length-1];
};
Array.prototype.secondToLast = function() {
  return this[this.length-2];
};
function sumFibs(num) {
  var sequence = [1,1];
  while (sequence.secondToLast() + sequence.last() <= num) {
...