Custom URL: Launch app if app is installed, else open an alternate URL (iOS Safari only)

gistfile1.js

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

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

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

        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>

Hi,

When i try this, am getting error as ' Safari cannot open the page because the address is invalid. I have installed the app in iPad. Check my below code.
document.location = "Metro-TV://";