Nodejs Utililty Methods Week Get

Date.prototype.getWeek = function (dowOffset) {
    dowOffset = typeof(dowOffset) == 'int' ? dowOffset : 1; 
    var newYear = new Date(this.getFullYear(),0,1);
    var day = newYear.getDay() - dowOffset; 
    day = (day >= 0 ? day : day + 7);
  var daynum = Math.floor((this.getTime() - newYear.getTime() - 
  (this.getTimezoneOffset()-newYear.getTimezoneOffset())*60000)/86400000) + 1;
  var weeknum;
  if(day < 4) {
...

Date.prototype.getWeek = function (dowOffset) {
  dowOffset = typeof(dowOffset) == 'int' ? dowOffset : 0; 
  var newYear = new Date(this.getFullYear(),0,1);
  var day = newYear.getDay() - dowOffset; 
  day = (day >= 0 ? day : day + 7);
  var daynum = Math.floor((this.getTime() - newYear.getTime() -
  (this.getTimezoneOffset()-newYear.getTimezoneOffset())*60000)/86400000) + 1;
  var weeknum;
  if(day < 4) {
...

Date.prototype.getWeekDayName = function(){
  return this.weekDayName()[this.getDay()];
};
Date.prototype.weekDayName = function(){
  return ['Sunday','Monday','Tuesday','Wednesday','Thursday','Friday','Saturday'];
};
sec = 1000;
min = 60*sec;
hour = 60*min;
...

Date.prototype.getWeekDayName = function(lang) {
    lang = lang && (lang in Date.locale) ? lang : 'de';
    return Date.locale[lang].day_names[this.getDay()];
};
Date.locale = {
    de: {
        month_names: ['Januar', 'Februar', 'M?', 'April', 'Mai', 'Juni', 'Juli', 'August', 'September', 'Oktober', 'November', 'Dezember'],
        month_names_short: ['Jan', 'Feb', 'M?, 'Apr', 'Mai', 'Jun', 'Jul', 'Aug', 'Sep', 'Okt', 'Nov', 'Dez'],
        day_names: ['Sonntag', 'Montag', 'Dienstag', 'Mittwoch', 'Donnerstag', 'Freitag', 'Samstag'],
...

Date.prototype.getWeekDayNameShort = function(lang) {
    lang = lang && (lang in Date.locale) ? lang : 'de';
    return Date.locale[lang].day_names_short[this.getDay()];
};
Date.locale = {
    de: {
        month_names: ['Januar', 'Februar', 'M?', 'April', 'Mai', 'Juni', 'Juli', 'August', 'September', 'Oktober', 'November', 'Dezember'],
        month_names_short: ['Jan', 'Feb', 'M?, 'Apr', 'Mai', 'Jun', 'Jul', 'Aug', 'Sep', 'Okt', 'Nov', 'Dez'],
        day_names: ['Sonntag', 'Montag', 'Dienstag', 'Mittwoch', 'Donnerstag', 'Freitag', 'Samstag'],
...

Date.prototype.getWeekNumber = function(){
    const date = new Date(+this);
    date.setHours(0,0,0);
    date.setDate(date.getDate()+4-(date.getDay()||7));
    return Math.ceil((((date-new Date(date.getFullYear(),0,1))/8.64e7)+1)/7);
};

Date.prototype.getWeekNumber = function(){
    var d = new Date(+this);
    d.setHours(0,0,0);
    d.setMilliseconds(0);
    d.setDate(d.getDate()+4-(d.getDay()||7));
    return Math.ceil((((d-new Date(d.getFullYear(),0,1))/8.64e7)+1)/7);
};

Date.prototype.getWeekNumber = function(){
  var d = new Date(+this);
  d.setHours(0,0,0);
  d.setDate(d.getDate()+4-(d.getDay()||7));
  return Math.ceil((((d-new Date(d.getFullYear(),0,1))/8.64e7)+1)/7);
};
function(doc) {
  var docdate = new Date(doc.created_at);
  if (doc.type === "entry")
...

Date.prototype.getWeekNumber = function() {
    var target = new Date(this.valueOf());
    var dauNumber = (this.getDay() + 6) % 7;
    target.setDate(target.getDate() - dauNumber + 3);
    var jan4 = new Date(target.getFullYear(), 0, 4);
    var dayDiff = (target - jan4) / 86400000;
    if (new Date(target.getFullYear(), 0, 1).getDay() < 5) {
        return 1 + Math.ceil(dayDiff / 7);
    else {
        return Math.ceil(dayDiff / 7);

Date.prototype.getWeekNumber = function(){
    var d = new Date(+this);
    d.setHours(0,0,0);
    d.setDate(d.getDate()+4-(d.getDay()||7));
    return Math.ceil((((d-new Date(d.getFullYear(),0,1))/8.64e7)+1)/7);
};