(function() {
  var url = window.location.href;
  var sn = "";

  if (url.indexOf("sn=") !== -1) {
    sn = url.split("sn=")[1].split("&")[0];
  }

  if (sn) {
    document.getElementById("sn-code").textContent = "SN: " + sn;
  }
})();