CustomURL: Launch app if app is installed, else open an alternate URL (iOS all browsers)

gistfile1.js

    <script type="text/javascript">
        var timer;
        var heartbeat;
        var lastInterval;

        function clearTimers() {
            clearTimeout(timer);
            clearTimeout(heartbeat);
        }

        window.addEventListener("pageshow", function(evt){
            clearTimers();
        }, false);

        window.addEventListener("pagehide", function(evt){
            clearTimers();
        }, false);

        function getTime() {
            return (new Date()).getTime();
        }

        // For all other browsers except Safari (which do not support pageshow and pagehide properly)
        function intervalHeartbeat() {
            var now = getTime();
            var diff = now - lastInterval - 200;
            lastInterval = now;
            if(diff > 1000) { // don't trigger on small stutters less than 1000ms
                clearTimers();
            }
        }

        function launch_app_or_alt_url(el) {
            lastInterval = getTime();
            heartbeat = setInterval(intervalHeartbeat, 200);
            document.location = 'myapp://customurl';
            timer = setTimeout(function () {
                document.location = 'http://alternate.url.com';
            }, 2000);
        }

        $(".source_url").click(function(event) {
            launch_app_or_alt_url($(this));
            event.preventDefault();
        });
    </script>

@cweekly Belatedly:

I am implementing this as its own page on my subdomain that is opened for the desired page with a normal a link that specifies target=_blank. The timeout then has a window.close() in it.

window.location.href = deepLink;

var now = new Date().valueOf();
setTimeout(function() {
    if (new Date().valueOf() - now < 100) {
        window.location.href = installAppLink;
    }

    window.close();
}, 1000);

This seems to get around the issues with 'invalid address' as the window will be automatically closed - users may still see it for a brief second. Also this isolates the awful ios hackery to one page on the site.