I have some ajax calls on the document of a site that display or hide a progress bar depending on the ajax status
$(document).ajaxStart(function(){
Furthermore, if you want to disable calls to .ajaxStart() and .ajaxStop(), you can set global option to false in your .ajax() requests ;)
.ajaxStart()
.ajaxStop()
global
false
.ajax()
See more here : How to call .ajaxStart() on specific ajax calls