Nodejs Utililty Methods Date Format

Date.prototype.format = function (strFormat) {
  'use strict';
  var d = new Date(this),
    mon = ['', 'Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun', 'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec'],
    month = ['', 'January', 'February', 'March', 'April', 'May', 'June', 'July', 'August', 'September', 'October', 'November', 'December'],
    day = ['Sun', 'Mon', 'Tue', 'Wed', 'Thu', 'Fri', 'Sat'],
    weekday = ['Sunday', 'Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday', 'Saturday'],
    v = {
      's': String(d.getSeconds()),
...

Date.prototype.format1 = function() {
    return "" + this.getMonth() + this.getFullYear();
function f(d) {
    for (var i=0; i<60; i++) {
        assertEq(d.format1(), "91987");
f(new Date("10/10/1987 1:11:11"));
...

function formatAMPM(date) {
  var hours = date.getHours();
  var minutes = date.getMinutes();
  var ampm = hours >= 12 ? 'pm' : 'am';
  hours = hours % 12;
  hours = hours ? hours : 12; 
  minutes = minutes < 10 ? '0'+minutes : minutes;
  var strTime = hours + ':' + minutes + ' ' + ampm;
  return strTime;
...

function formatDate(date) {
  if(date instanceof Date === false) {
    return console.log("err");
  var year = date.getFullYear();
  var month = pad(date.getMonth() + 1);
  var day = pad(date.getDate());
  return [year, month, day].join('-');

function formatDate(date){
  return date.split('-').reverse().join('/');

Date.prototype.formatDate = function(format) {
  var date = this,
    day = date.getDate(),
    month = date.getMonth() + 1,
    year = date.getFullYear(),
    hours = date.getHours(),
    minutes = date.getMinutes(),
    seconds = date.getSeconds();
  if (!format) {
...

Date.prototype.formatDate = function (format) {
    var date = this,
        day = date.getDate(),
        month = date.getMonth() + 1,
        year = date.getFullYear(),
        hours = date.getHours(),
        minutes = date.getMinutes(),
        seconds = date.getSeconds();
    if (!format) {
...

Date.prototype.formatDate = function(format) {
  var months = new Array("Jan","Feb","Mar","Apr","May","Jun","Jul","Aug","Sep","Oct","Nov","Dec");
  var yyyy = this.getFullYear();
  var yy = yyyy.toString().substring(2);
  var m = this.getMonth() + 1;
  var mm = m < 10 ? "0" + m : m;
  var mmm = months[m - 1];
  var d = this.getDate();
  var dd = d < 10 ? "0" + d : d;
...

Date.prototype.formatDay = function (pattern, dayNames = [], monthnames = []) {
    pattern = pattern.replace(/dddd/g, dayNames[this.getDay()]);
    pattern = pattern.replace(/dd/g, this.getDate().toString().padLeft(2, 0));
    pattern = pattern.replace(/mmm/g, monthnames[this.getMonth()]);
    pattern = pattern.replace(/mm/g, (this.getMonth() + 1).toString().padLeft(2, 0));
    pattern = pattern.replace(/yyyy/g, this.getFullYear().toString());
    pattern = pattern.replace(/yy/g, this.getFullYear().toString().substr(2, 2));
    return pattern;
};
...

Date.prototype.formatMMDD = function () {
   return this.getMonth() + 1 + '/' + this.getDate();
};