Add the domain to assets CCS and JS

I would like to upload CCS and JS from https://static.example.com. The typical page contains:


and it contains simulated entries for JS. I would like to add https://static.example.com in front of href = "URL" for CCS and JS.

I am aware that this can be done with a contrib module. I would like to find a HOOK or some other way to add this to my custom module.

Thanks greg