// get root url of a shop page
function st_root()
{
    var url = document.URL;
    var protocol = document.location.protocol + '//';
    var base = url.substring(0, url.indexOf('/', protocol.length));  
 
    if (document.location.protocol != 'https:') {
        return base;
    }
    
    // if https, match shop root of /shops/id/page
    var root = url.substring(0, url.indexOf('/', base.length+7));
    
    return root;
}

// strip our root from the url
function st_strip_root(url)
{
    if (!url || url == '') {
        return '';
    }

    var root = st_root();

    var p = url.indexOf(root);

    if (p == 0) {
        url = url.substring(root.length);
    }

    return url;
}


function st_referrer()
{
    return st_strip_root(document.referrer);
}

function st_url()
{
    return st_strip_root(document.URL);
}

function st_img()
{
    return st_root() + '/st/img';
}

var img = new Image(1,1);
img.src = st_img()+'?url='+escape(st_url())+'&ref='+escape(st_referrer());