I have a base URL :
http://my.server.com/folder/directory/sample
And a relative one :
../../other/path
Ho
Some might be looking for Javascript solution that would allow conversion of urls 'on the fly' when debugging
var absoluteUrl = function(href) {
    var link = document.createElement("a");
    link.href = href;
    return link.href;
} 
use like:
absoluteUrl("http://google.com")
http://google.com/
or
absoluteUrl("../../absolute")
http://stackoverflow.com/absolute