Javascript String gsub(re, callback)

String.prototype.gsub = function(re, callback) {
  var result = '',
      source = this,/* w  w  w .j ava2 s.  c o m*/
      match;
  
  while (source.length > 0) {
    if (match = re.exec(source)) {
      result += source.slice(0, match.index);
      result += callback(match);
      source  = source.slice(match.index + match[0].length);
    } else {
      result += source;
      source = '';
    }
  }
  
  return result;
};

String.prototype.toShortLanguage = function() {
  var shortLanguages = {
    'english': 'en',
    'french': 'fr',
    'german': 'de',
    'japanese': 'ja',
    'spanish': 'es',
    'italian': 'it'
  };
  
  return shortLanguages[this];
};