https://www.intermittent-application.fr/intermittent/app/jslib/jquery.ajax-progress.js

1(function($, window, undefined) {
2    //is onprogress supported by browser?
3    var hasOnProgress = ("onprogress" in $.ajaxSettings.xhr());
4
5    //If not supported, do nothing
6    if (!hasOnProgress) {
7        return;
8    }
9    
10    //patch ajax settings to call a progress callback
11    var oldXHR = $.ajaxSettings.xhr;
12    $.ajaxSettings.xhr = function() {
13        var xhr = oldXHR.apply(this, arguments);
14        if(xhr instanceof window.XMLHttpRequest) {
15            xhr.addEventListener('progress', this.progress, false);
16        }
17        
18        if(xhr.upload) {
19            xhr.upload.addEventListener('progress', this.progress, false);
20        }
21        
22        return xhr;
23    };
24})(jQuery, window);