Upload files using jQuery Ajax to PHP

HTML:

 <form id="upload" method="post" enctype="multipart/form-data">
      <input type="file" name="file" id="file"><br>
      <input type="submit" id="upload_button" name="upload_button" value="Upload">
 </form>

Javascript/jQuery:

$("#filefont").on("change", function(){
    var fileupload = document.getElementById("upload_font");

    formdata = new FormData(fileupload);

    var xmlreq = new XMLHttpRequest();
    xmlreq.open("POST", "uploadfont.php", true);
    xmlreq.onreadystatechange = function(event){
        if(xmlreq.readyState == 4 && xmlreq.status == 200){
            alert(xmlreq.responseText);
        }
    }
    xmlreq.send(formdata);
})

The javascript/jquery I have is something I just found off the internet. I tried lots of approaches but I can't seem to find a working way.

I already have a code in PHP, I just can't get the FILES from AJAX/JQuery.