code: function random(length, options) {
    length || (length = 8);
    options || (options = {});
  
    var chars = '';
    var result = '';
  
    if (options === true) {
      chars = numbers + letters + specials;
    } else if (typeof options == 'string') {
      chars = options;
    } else {
      if (options.numbers !== false) {
        chars += (typeof options.numbers == 'string') ? options.numbers : numbers;
      }
  
      if (options.letters !== false) {
        chars += (typeof options.letters == 'string') ? options.letters : letters;
      }
  
      if (options.specials) {
        chars += (typeof options.specials == 'string') ? options.specials : specials;
      }
    }
  
    while (length > 0) {
      length--;
      result += chars[Math.floor(Math.random() * chars.length)];
    }
    return result;
  }
docs: Generate random string
  @param {Number} length
  @param {Object} options