I have a google form that outputs responses to a google sheet. I would like to learn how to write a script that manipulates the data before saving the response to the sheet.

Basically I have a few form values, among them are “Your Class?”, “Your Division?”, “Your Department?”. These fields are all optional except department. However if someone were to enter a value into division I want it to overwrite the stored value for department for this submission. Likewise if someone enters a value for all three I want it to store class as the value for department.

This sounds clunky but is needed for filter views used in the spreadsheet. Any guidance appreciated.