Is there a place that I can get more information on HTTPS file

I am trying to download available files from an HTTPS connection. I can
connect and get to where I need to be but I am not getting the data
that I need in order to download the files.

First the website that I am connecting to is written in JavaScript, (if
that matters)

Second I will not know the entire file name(s) that I need to retrieve.

Any help would be appreciated. Thank you in advance.