<html> 
  <head>
    <title>Loading...</title>
  </head>
  <body onload="attachUnloadListener()"> 
    <script> 
      function attachUnloadListener() {
        window.addEventListener('unload', onUnload, false);
        document.title = "sync xhr on unload";
      }

      var req = new XMLHttpRequest();
      function onUnload() {
        req.open('GET','download-test1.lib', false);
        req.send(null);
      }
    </script> 
    <p>Navigate to another page to trigger synch xmlhttprequest</p>
  </body> 
</html>