The ajaxStart Event is ignored for the first time when ajax function is called from JQuery.

Below is the sample code which ran with JQuery 1.8.3

$.ajax({

type : 'get',

url : 'tasks.json',

dataType : 'json',

});

$(this).ajaxStart(function(){

console.log("ajaxStart");

});

$(this).ajaxStop(function(){

console.log("ajaxStop");

});

when you run this code... for the first time the ajaxStart event will be ignored and direct ajaxStop event will be called.. but for all other successive call's the ajaxStart event is also getting triggered...

Basic Investigation based of JQuery 1.8.3 version :

below code inside trigger function is avoiding ajaxStart event to get executed and this is because for the first time when we trigger ajaxStart event its not present under jQuery.event.global Array list..

if ( (!elem || jQuery.event.customEvent[ type ]) && !jQuery.event.global[ type ] ) {

// No jQuery handlers for this event type, and it can't have inline handlers

return;

}