Thanks for the suggestion Jonathan.
I want to pre-fill a select field within a repeater row, based off the same sub-field in the previous row, before any of the data is saved to the database so JavaScript is the only option I can see.
I noticed the select2_args filter on the bottom of the Adding custom javascript to fields page, but its documentation is minimal. I assume $select is the current field, but args and settings are not clear.
Can you provide more detail about this filter and how it works?
