I already have quite a bit of js on my site, so I want to have a function that grabs the domain name of the current url as efficiently as possible.

Example:

input : https://stackoverflow.com/questions/ask

result : stackoverflow.com

input : http://test.stackoverflow.com/questions/ask

result : test.stackoverflow.com

I guess the best way to start is with document.location, but I'm at odds what to do from there.