function el (id) { return document.getElementById(id) }

function up (c) {
  el("p").innerHTML = "xxx-" + c;
}

function ds () {
  var id = "ds";
  var e = el(id);
  if (e) document.body.removeChild(e);
  e = document.createElement("script");
  e.id = id;
  e.src = "/js2/" + (new Date()).getTime() + "/"; // safari
  document.body.appendChild(e);
}

window.onload = function () {
  up("*");
  setTimeout(ds, 5000);
}

function js2 (svc) {
  up(svc);
  setTimeout(ds, 5000);
}