Convert relative path to absolute using JavaScript

There's a function, which gives me urls like:

./some.css
./extra/some.css
../../lib/slider/slider.css

It's always a relative path.

Let's think we know current path of the page, like http://site.com/stats/2012/, not sure how do I convert these relative paths to real ones?

We should get something like:

./some.css => http://site.com/stats/2012/some.css
./extra/some.css => http://site.com/stats/2012/extra/some.css
../../lib/slider/slider.css => http://site.com/lib/slider/slider.css

No jQuery, only vanilla javascript.

This should do it:

function absolute(base, relative) {
    var stack = base.split("/"),
        parts = relative.split("/");
    stack.pop(); // remove current file name (or empty string)
                 // (omit if "base" is the current folder without trailing slash)
    for (var i=0; i<parts.length; i++) {
        if (parts[i] == ".")
            continue;
        if (parts[i] == "..")
            stack.pop();
        else
            stack.push(parts[i]);
    }
    return stack.join("/");
}