N/error Module
UserEventError.eventType
Property Description: User event type (beforeLoad, beforeSubmit, or afterSubmit)
Type: string (read-only)
Supported Script Types: User event scripts For more information, see SuiteScript 2.0 User Event Script Type.
Module: N/error Module
Since: 2015.2
Search NetSuite - https://system.netsuite.com/app/help/helpcenter.nl?search=UserEventError.eventType

// Code Example 1

//Add additional code

//...

var UEcustom_error = error.create({

    name: 'MY_ERROR_CODE',

    message: 'my custom UserEventError details',

    notifyOff: false

});

log.debug("User Event Type: " + UEcustom_error.eventType); // eventType is set by the system

                                                          // 'User Event Type: ' followed by the eventType will be logged

//...

//Add additional code



//SOURCE: https://system.netsuite.com/app/help/helpcenter.nl?fid=section_4243803835.html