Nunjucks with custom filter for number_format

javascript.json

"paths": {
  "nunjucks": "../Vendor/nunjucks/dist/js/nunjucks"
},
"map": {
  "*": {
    "nunjucks": "Service/Factory/nunjucksFactory/nunjucksFactory"
  },
  "Service/Factory/nunjucksFactory/nunjucksFactory" : {
    "nunjucks" : "nunjucks"
  }
}

nunjucksFactory.js

define(['nunjucks', 'nunjucksEnv'], function (nunjucks, nunjucksEnv) {
  'use strict';
  
  var numberFormat;
  
  numberFormat = function (value, decimalNumbers, decimalSeparator, thousandSeparator) {
    var newNumberAsString;
  
    if (value == null || typeof value !== 'number' isNaN(value)) {
      value = 0;
    }
  
    newNumberAsString = value.toFixed(decimalNumbers).toString();
  
    if (decimalSeparator != null) {
      newNumberAsString = newNumberAsString.replace(/\./g, decimalSeparator);
    }
  
    if (thousandSeperator != null) {
      newNumberAsString = newNumberAsString.replace(/\B(?=(\d{3})+(?!\d))/g, thousandSeparator);
    }
  
    return newNumberAsString;
  };
  
  nunjucks.configure({ autoescape: true });
  nunjucksEnv.addFilter('number_format', numberFormat);
  
  return nunjucks;
});

template.twig

<span itemprop="price" content="{{ price | number_format(2, '.') }}">
  {{ price | number_format(2, ',', '.') }}
</span>

Hi. Variable name spelling mistake - https://gist.github.com/michsch/9ba3d1d3348294bf65e1d813876c8915#file-nunjucksfactory-js-L19