Tracking script zoals analytics

$('<img>', {
    src: statsPage + '?' + params
}).appendTo('body').remove()

<script type="text/javascript">
var statsPage = 'http://www.my-url.com/response.php';

var p = {
      type: "pageview", //Type: pageview, form, ...
      userid:1,
      gender: "male",
}

var params = Object.keys(p).map(function(k) {
    return encodeURIComponent(k) + '=' + encodeURIComponent(p[k])
}).join('&')

const req = new XMLHttpRequest();
//req.addEventListener('load' /*callback after req is complete*/);
req.open('GET', statsPage + '?' + params);
req.send();

req.onreadystatechange = function() {
    if (req.readyState == XMLHttpRequest.DONE) {
        alert(req.responseText);
    }
}
</script>

<script type="text/javascript">
var statsPage = 'http://www.my-url.com/response.php';

function ca(c,o,n,t,e,t,u){return p={type:c,userid:o,gender:n}}

ca("pageview", "1", "male");

var params = Object.keys(p).map(function(k) {
    return encodeURIComponent(k) + '=' + encodeURIComponent(p[k])
}).join('&')

const req = new XMLHttpRequest();
//req.addEventListener('load' /*callback after req is complete*/);
req.open('GET', statsPage + '?' + params);
req.send();

req.onreadystatechange = function() {
    if (req.readyState == XMLHttpRequest.DONE) {
        alert(req.responseText);
    }
}
</script>

    var startTime = new Date();        //Start the clock!
    window.onbeforeunload = function()        //When the user leaves the page(closes the window/tab, clicks a link)...
    {
        var endTime = new Date();        //Get the current time.
        var timeSpent = (endTime - startTime);        //Find out how long it's been.
        var xmlhttp;        //Make a variable for a new ajax request.
        if (window.XMLHttpRequest)        //If it's a decent browser...
        {
            // code for IE7+, Firefox, Chrome, Opera, Safari
            xmlhttp = new XMLHttpRequest();        //Open a new ajax request.
        }
        else        //If it's a bad browser...
        {
            // code for IE6, IE5
            xmlhttp = new ActiveXObject("Microsoft.XMLHTTP");        //Open a different type of ajax call.
        }
        var url = "http://www.my-url.com/response.php?userID=1&pag_titel=1&datum=1&time="+timeSpent;        //Send the time on the page to a php script of your choosing.
        xmlhttp.open("GET",url,false);        //The false at the end tells ajax to use a synchronous call which wont be severed by the user leaving.
        xmlhttp.send(null);        //Send the request and don't wait for a response.
		
    }

window.onbeforeunload = function()  {  
var xhr = new XMLHttpRequest();
xhr.open('GET', 'http://www.digital-productions.be/dev/analytics/response.php?pag_titel=1', true);

// If specified, responseType must be empty string or "text"
xhr.responseType = 'test';

xhr.onreadystatechange = function() {
    if (xhr.readyState == XMLHttpRequest.DONE) {
        alert(xhr.responseText);
    }
}

xhr.send(null); 

    }