(function() {
    function extractParamFromUri(uri, paramName) {
        if (!uri) {
            return;
        }
        var parts = uri.split('?');  
        if (parts.length == 1) {
            parts = uri.split('#');
            if (parts.length == 1) {
                return;
            }
        }
        var query = decodeURI(parts[1]);
        paramName += '=';
        var params = query.split('&');
        for (var i = 0, param; param = params[i]; ++i) {
            if (param.indexOf(paramName) === 0) {
              return unescape(param.split('=')[1]);
            }
        }
    }
    if (window.twttr) {
        twttr.events.bind('tweet', function(event) {
          if (event) {
            var targetUrl;
            if (event.target && event.target.nodeName == 'IFRAME') {
              targetUrl = extractParamFromUri(event.target.src, 'url');
            }
            _gaq.push(['_trackSocial', 'twitter', 'tweet', targetUrl]);
          }
        });
    }
}) ();