module.exports = function str_rot13(str) {
  //  discuss at: https://locutus.io/php/str_rot13/
  // original by: Jonas Raoni Soares Silva (https://www.jsfromhell.com)
  // improved by: Ates Goral (https://magnetiq.com)
  // improved by: Rafał Kukawski (https://blog.kukawski.pl)
  // bugfixed by: Onno Marsman (https://twitter.com/onnomarsman)
  //   example 1: str_rot13('Kevin van Zonneveld')
  //   returns 1: 'Xriva ina Mbaariryq'
  //   example 2: str_rot13('Xriva ina Mbaariryq')
  //   returns 2: 'Kevin van Zonneveld'
  //   example 3: str_rot13(33)
  //   returns 3: '33'

  return (str + '').replace(/[a-z]/gi, function (s) {
    return String.fromCharCode(s.charCodeAt(0) + (s.toLowerCase() < 'n' ? 13 : -13))
  })
}