run the onchange catalog client script when Variable is already having that value autopopulated

[ServicenowDev19]

I have a order guide with multiple catalog items. I have written a onchange catalog client script for Scenario that when Request type is Add then show a popup.This is working when i select request type as Add.

But When catalog item in order guide is autopopulated with request type as Add then this script is not working.

How to make  this script executable when variable is already autopopulated as request type Add on catalog item.

Script:

[ServicenowDev19]

cascade variable checkbox is already false.And not getting from where the value is being Populated.No client script is their.I think From Widget it is getting autopoplaed but not sure.So i am trying to work that script when variae is auopopulated.