Javascript - jQuery Ajax Progress

jquery.ajax.progress.js

// Live demo
// http://jsfiddle.net/GvdSy/

$.ajax({
     xhr: function () {
         var xhr = new window.XMLHttpRequest();
         xhr.upload.addEventListener("progress", function (evt) {
             if (evt.lengthComputable) {
                 var percentComplete = evt.loaded / evt.total;
             }
         }, false);
         xhr.addEventListener("progress", function (evt) {
             if (evt.lengthComputable) {
                 var percentComplete = evt.loaded / evt.total;
             }
         }, false);
         return xhr;
     },
     type: 'POST',
     url: "/",
     data: data,
     success: function (data) {}
 });