Nodejs Utililty Methods Currency Format

Number.prototype.toCurrency = function(decimalPlaces){                               
  decimalPlaces = (decimalPlaces === undefined) ? 2 : decimalPlaces;
  var nStr = (decimalPlaces != null) ? this.toFixed(decimalPlaces) : this.toString();
  var x = nStr.split('.');
  var x1 = x[0];
  var x2 = x.length > 1 ? ',' + x[1] : '';
  var rgx = /(\d+)(\d{3})/;
  while (rgx.test(x1)) {
    x1 = x1.replace(rgx, '$1' + '.' + '$2');
...

Number.prototype.toCurrency = function(decimals, decimal_sep, thousands_sep)
   var n = this,
   c = isNaN(decimals) ? 2 : Math.abs(decimals), 
   d = decimal_sep || ',', 
   t = (typeof thousands_sep === 'undefined') ? '.' : thousands_sep, 
   sign = (n < 0) ? '-' : '',
   i = parseInt(n = Math.abs(n).toFixed(c)) + '', 
   j = ((j = i.length) > 3) ? j % 3 : 0; 
...

Number.prototype.toBillions = function() {
  return (this / 1000000000).toFixed(1) + 'B';
};

Number.prototype.currency = function() {
    return (this.toFixed(2)+"").replace(',','.');

Number.prototype.currencyFormat = function( symbol )
  this.number = parseFloat( this ).toFixed(2);
  while ( /(\d+)(\d{3})/.test( this.number.toString() ) ) {
    this.number = this.number.toString().replace( /(\d+)(\d{3})/, '$1'+','+'$2' );
  return symbol + this.number;

Number.prototype.currencyFormat=function(fixed){
  var fixed=fixed||0;
  var str=this.toFixed(fixed);
  return str.replace(/(\d)(?=(\d\d\d)+(?!\d))/g, "$1,");

'use strict';
Number.prototype.setCurrency = function() {
    var re = '\\d(?=(\\d{' + (3) + '})+' + (2 > 0 ? '\\.' : '$') + ')';
    return this.toFixed(Math.max(0, ~~2)).replace(new RegExp(re, 'g'), '$&,');
};