code: function randomString(length) {
    var bits = 36,
        tmp,
        out = "";
    while (out.length < length) {
      tmp = Math.random().toString(bits).slice(2);
      out += tmp.slice(0, Math.min(tmp.length, (length - out.length)));
    }
    return out.toUpperCase();
  }
docs: Provide a random string