How does the regex work?

[shiny-ribbon]

I thought I knew a little bit of regex, but guess not.
I couldn't figure out how to make a regex to match a site homepage but not its subpages
I tried some variations of

https:\/\/reddit\.com
^https:\/\/www\.reddit\.com$
^(https:\/+(www\.)?reddit\.com)$

No luck

[shiny-ribbon]

Never mind, ended up finding a tapatalk thread where the person had the exact same problem. In the end I went from there.
My final regex looks like this

^(https?|file):\/+((www\.)?(reddit|discord)\.com(\/(r|message)\/(all|popular|inbox|portugal))?\/?)$

It covers the reddit homepage, a few specific subpages, but only those, as well as discord for good measure
As for interpreting it? I can't do it

[proginosko]

Yes, it's tricky, but that should do it.