Upload

upload.js

var chunkSize = 1048; //default chunksize

var a = new XMLHttpRequest();
a.onreadystatechange = function() {
    if (a.readyState == 4 && a.status == 200) {
        var timeToLoad = new Date - startPingDate;
        chunkSize = Math.round(chunkSize - (timeToLoad * Math.random()));

        if (chunkSize < 256)
            chunkSize = 256; //set a default value if too low   

        $("#chunkSize").html(chunkSize);
        $("#toSize").html(toSize(1 * 1024 * chunkSize));

    }
};

var startPingDate = new Date;
a.open("GET", "/pingImage.jpg");
a.send(null);

alert(chunksize);