I'm making a few assumptions, which may be unfair.
The major assumption I'm making is that you already know how to make an XMLHTTPRequest type JS call to a web based endpoint. If that's something you aren't familiar with, that's fine. I'd say that is what you need to get comfortable with.
My notes above explain how to setup a browserview by reusing an existing function that you are already using (getImportfields). Once you're fine with XMLHTTPRequests you should be able to do what you need with the proposed browserview.