i was trying to make an tester for a handler to open an app and if the app isnt there than open the download page but with the code i have it doesnt work exactly how i would like it mabye someone can help me in the right direction

<li onclick="openWebexContent()" class="li-slider">
                            <a class="btn-app">WBX</a>
                        </li>

function openWebexContent() {
    var appURI = "webex:";
    var fallbackURL = "https://webex.com/downloads.html";
    var appOpened = false;

    var iframe = document.createElement('iframe');
    iframe.style.display = 'none';
    iframe.src = appURI;
    document.body.appendChild(iframe);

setTimeout(function () {
        if (!appOpened) {
            document.body.removeChild(iframe);
            var downloadConfirmation = confirm("Webex kon niet worden geopend! Klik op OK om het te downloaden.");
            if (downloadConfirmation) {
                window.open(fallbackURL, '_blank');
            } else {
                alert("Er is iets fout gegaan");
            }
        }
    }, 1000);

    iframe.onload = function () {
        appOpened = true;
    };
}