update-favicon-on-gh-check.js

(function() {
    // Updates GitHub favicon on pull request pages depending on it's check's status
    // if the last checked status was 'pending' 
    //    it will refresh every 5 minutes if you leave the tab
    //    and will refresh once more when you re-enter it
    // if the status was 'success' or 'failure' - it will just update the favicon
    is_pending = function() { return !!document.querySelector('.donut-chart>.pending'); };
    is_failure = function() { return !!document.querySelector('.donut-chart>.failure'); };

    update_favicon = function() {
        pending = is_pending();
        failure = is_failure();

        pending_ico = 'https://cloud.githubusercontent.com/assets/61051/21805979/615b9d54-d737-11e6-8eb5-f473f3167e60.png';
        failure_ico = 'https://cloud.githubusercontent.com/assets/61051/21805980/615bd44a-d737-11e6-8f7e-d3e8e8382712.png';
        success_ico = 'https://cloud.githubusercontent.com/assets/61051/21805981/615c29b8-d737-11e6-8c2e-684742e5da9a.png';

        link = document.querySelector("link[rel='icon']");
        if(pending) {
            link.href = pending_ico;
        } else if(failure) {
            link.href = failure_ico;
        } else {
            link.href = success_ico;
        }

        document.getElementsByTagName('head')[0].appendChild(link);
    };

    update_favicon();

    refresh_rate = 5 * 60 * 1000;

    if(is_pending()) {
        if(document.hidden) {
          setTimeout(function() { window.location.reload(true) }, refresh_rate);  
        }

        document.addEventListener('visibilitychange', function(){
            if(document.hidden) {
                setTimeout(function() { window.location.reload(true) },refresh_rate); 
            } else {
                window.location.reload(true);
            }
        });
    }
})();

icons: