Handle js event in Bitrix?

Question

JavaScript

Hello!
How, when adding a product to the comparison, you can track this event, I tried:

BX.onCustomEvent("OnCompareChange",function () {
        alert("sssssssss");
 });

It is required to get json which returns:
/catalog/compare/?action=ADD_TO_COMPARE_LIST&id=1164&ajax_action=Y
How can this be done?