Detect if visitor is logged into Google, Google Plus, Taringa! or Twitter

service-status.js

// check<Service>Status([ onSuccess, onFailure ]);
// i.e checkTaringaStatus(function () { alert('+10'); });
(function () {
    var checkServiceStatus = function (image, success, error) {
        return function (success, error) {
            var img = new Image();
            img.onload = success || function () {};
            img.onerror = error || function () {};
            img.src = image;
        };
    };

    window.checkGoogleStatus = checkServiceStatus("https://accounts.google.com/CheckCookie?continue=https%3A%2F%2Fwww.google.com%2Fintl%2Fen%2Fimages%2Flogos%2Faccounts_logo.png&followup=https%3A%2F%2Fwww.google.com%2Fintl%2Fen%2Fimages%2Flogos%2Faccounts_logo.png&chtml=LoginDoneHtml&checkedDomains=youtube&checkConnection=youtube%3A291%3A1");
    window.checkGooglePlusStatus = checkServiceStatus("https://plus.google.com/up/?continue=https://www.google.com/intl/en/images/logos/accounts_logo.png&type=st&gpsrc=ogpy0");
    window.checkTaringaStatus = checkServiceStatus("https://www.taringa.net/login?redirect=/img/logo.png");
    window.checkTwitterStatus = checkServiceStatus("https://twitter.com/login?redirect_after_login=%2Fimages%2Fspinner.gif");
}());

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