"Override" the "callback" function triggered after infopath executes an async call on an infopath browser enabled form

CurrentFormData_SetFormData.js

 (function () {
            var nCurrentFormData_SetFormData = CurrentFormData_SetFormData;
            CurrentFormData_SetFormData = function () {
                nCurrentFormData_SetFormData.apply(this, arguments);
                //Your custom code here                
            }
        })();