I know I can get the host name of the current page, by simply doing:

var myhostname = location.hostname;

But how do I get the host name of the referrer? I can get the referrer by

var referrer = document.referrer;

but unfortunately there's no document.referrer.hostname available in JavaScript. How can I get this value?

An example of where this is useful is if somebody clicks a link on google.com. I want to be able to retrieve google.com from the referrer (not the page and the query string).