Detect AJAX events with JavaScript

There are times when you might want to monitor AJAX requests made from a page.

The following provides a way to monitor AJAX events by URL and request payload.

var s_ajaxListener = new Object();
s_ajaxListener.tempOpen = XMLHttpRequest.prototype.open;
s_ajaxListener.tempSend = XMLHttpRequest.prototype.send;
s_ajaxListener.callback = function () {
console.log(this.method + ':' + this.url + '\n'+ this.data);
if(this.url == 'mypath'){
// actions
}
}

XMLHttpRequest.prototype.open = function(a,b) {
if (!a) var a='';
if (!b) var b='';
s_ajaxListener.tempOpen.apply(this, arguments);
s_ajaxListener.method = a;
s_ajaxListener.url = b;
if (a.toLowerCase() == 'get') {
s_ajaxListener.data = b.split('?');
s_ajaxListener.data = s_ajaxListener.data[1];
}
}

XMLHttpRequest.prototype.send = function(a,b) {
if (!a) var a='';
if (!b) var b='';
s_ajaxListener.tempSend.apply(this, arguments);
if(s_ajaxListener.method.toLowerCase() == 'post')s_ajaxListener.data = a;
s_ajaxListener.callback();
}

From: https://stackoverflow.com/questions/3596583/javascript-detect-an-ajax-event