Nodejs Utililty Methods Month Calculate

Date.prototype.beginning_of_month = function() {
  return new Date(this.getFullYear(), this.getMonth(), 1);

Date.prototype.countDaysMonth = function () {
    var monthStart = new Date(this);
    var monthEnd = new Date(this);
    monthEnd.setMonth(monthEnd.getMonth() + 1);
    var qtdeDias = Math.round((monthEnd - monthStart) / (1000 * 60 * 60 * 24));
    return qtdeDias
};

Date.prototype.end_of_month = function() {
  var month = this.getMonth() + 1;
  var year = this.getFullYear();
  if (month > 11) {
    month = 0;
    year++;
  return new Date(year, month, 0);

Date.prototype.getAbbrMonth = function() {
  switch(this.getMonth()) {
    case 0: return 'Jan';
    case 1: return 'Feb';
    case 2: return 'March';
    case 3: return 'Apr';
    case 4: return 'May';
    case 5: return 'Jun';
    case 6: return 'July';
...

Date.prototype.getCurrentMonthDays = function(){
        var thisTime = this.getTime();
        if(this.getMonth() == 11){
            this.setYear(this.getYear()+1);
            this.setMonth(0);
        else{
            this.setMonth(this.getMonth()+1);
        var currentDays = parseInt((this.getTime()-thisTime)/1000/60/60/24);
        this.setTime(thisTime);
        return currentDays; 

Date.prototype.getFirstDayOfMonth = function () {
    var day = (this.getDay() - (this.getDate() - 1)) % 7;
    return (day < 0) ? (day + 7) : day;

Date.prototype.getLastDateInMonth = function (months){
  months = parseInt(months);
  return new Date(this.getFullYear(), this.getMonth() + (months || 0) + 1, 0);

Date.prototype.getLastDayOfMonth = function () {
    var day = (this.getDay() + (Date.daysInMonth[this.getMonth()] - this.getDate())) % 7;
    return (day < 0) ? (day + 7) : day;

Date.prototype.getMonth2 = function () {
   var month = this.getMonth() + 1;
   return (month < 10 ? '0' : '') + month;
};

Date.prototype.getMonthEnd = function () {
  return new Date(this.getFullYear(), this.getMonth() + 1, 0);
};