This is a great trick, but there's an irritating IE bug. On the pathname attribute, IE doesn't add a leading slash on the pathname (whereas all other browsers do).

It can be corrected by doing:

    parser.pathname = parser.pathname.replace(/(^\/?)/,"/");

Further, because you're creating a DOM element, it's less performant than using a RegExp solution. That performance degradation will typically only surface if you're parsing a large number of URLs (for example, in a loop), rather than just 1 or 2.