cribbed from infinum.co

Change Page Title on tab lost focus

init = function () {
    var e, t, n;
    typeof document.hidden != "undefined" ? (e = "hidden", n = "visibilitychange", t = "visibilityState") : typeof document.mozHidden != "undefined" ? (e = "mozHidden", n = "mozvisibilitychange", t = "mozVisibilityState") : typeof document.msHidden != "undefined" ? (e = "msHidden", n = "msvisibilitychange", t = "msVisibilityState") : typeof document.webkitHidden != "undefined" && (e = "webkitHidden", n = "webkitvisibilitychange", t = "webkitVisibilityState"), t && $(document).on(n, function (e) {
        var n = "Come back! We miss you!";
        document[t] === "visible" && typeof window.originalDocumentTitle != "undefined" && (document.title = window.originalDocumentTitle), document[t] === "hidden" && document.title !== n && (window.originalDocumentTitle = document.title, document.title = n)
    }), 
}