var makeString = require('./helper/makeString');
  var defaultToWhiteSpace = require('./helper/defaultToWhiteSpace');
  var nativeTrimRight = String.prototype.trimRight;
  
  module.exports = function rtrim(str, characters) {
    str = makeString(str);
    if (!characters && nativeTrimRight) return nativeTrimRight.call(str);
    characters = defaultToWhiteSpace(characters);
    return str.replace(new RegExp(characters + '+$'), '');
  };