(function() {
    var l = (document.querySelector('[rev~="canonical"]')
             || document.querySelector('[rel~="alternate"][rel~="short"]')
             || document.querySelector('[rel~="shortlink"]')
             || document.querySelector('[rel~="alternate"][rel~="shorter"]'));
    if (l) {
        prompt("Short URL:", l.href);
    } else {
        window.shortUrlBookmarkletCallback = function(bitly) {
            if (bitly.status_code === 200) {
                prompt("Bit.ly URL:", bitly.data.url);
            } else {
                alert("Bit.ly error: " + bitly.status_txt);
            }
        };
        var s = document.createElement('script');
        s.type = 'text/javascript';
        s.src = ('http://api.bit.ly/v3/shorten'
            + '?longURL=' + encodeURIComponent(window.location.href)
            + '&domain=j.mp'
            + '&format=json'
            + '&callback=shortUrlBookmarkletCallback'
            + '&login=BITLY_USERNAME'
            + '&apiKey=BITLY_API_KEY');
        document.querySelector('head').appendChild(s);
    }
})();