Fastest way to detect external URLs

Question

What\'s the fastest method to detect if foo=\'http://john.doe\' is an external url (in comparsion to window.location.href)?

Answer 1

pseudosavant's answer didn't exactly work for me, so I improved it.

var isExternal = function(url) {
    return !(location.href.replace("http://", "").replace("https://", "").split("/")[0] === url.replace("http://", "").replace("https://", "").split("/")[0]);   
}