page.html

<script>
var vals = [];
var last_packets_num = 10;
callback = function(f){
  my_ip = f.ip;
  setInterval(calc,1000)
}
calc = function(){
  var x=new Date

  function response_cb(){
    vals.push(new Date() - x);
    if (vals.length > last_packets_num) {
        vals = vals.slice(vals.length - last_packets_num, vals.length);
    }

    var valssum = vals.reduce(function(prev, cur){ return prev + cur }, 0);
    avg = valssum / vals.length;

    document.getElementById('out').innerHTML = (my_ip+" / "+avg+" "+vals.length);
  }

  xx=new XMLHttpRequest;
  xx.open('HEAD','http://cdn.jsdelivr.net/jquery/2.1.4/jquery.min.js?x='+Math.random());
  xx.send();
  xx.onload = response_cb;
  xx.onerror = response_cb;
}
</script>
<script src="http://ipinfo.io/?callback=callback"></script>
<div id="out"></div>