What's an easy way to get the url in the current window minus the domain name?

alert(window.location.pathname);

Here's some documentation for you for window.location.

ADDITIONAL ANSWER:

window.location.pathname itself is just not enough because it doesn't include the query part, and also URN if exists:

Sample URI                      = "http://some.domain/path-value?query=string#testURN"
window.location.pathname result = "/path-value"
window.location.search result   = "?query=string"
pathname + search result        = "/path-value?query=string"

If you want to get all the values just except the domain name, you can use the following code:

window.location.href.replace(window.location.origin, "")

Or as @Maickel suggested, with a simpler syntax:

window.location.href.substring(window.location.origin.length);

This gets the following URL parts correctly:

http://some.domain/path-value?query=string#testURN
alert(window.location.href.replace(window.location.origin, ""))--> "/path-value?query=string#testURN"