Prevent ajax call if app cache is updated

I am writing a standalone web application.

I have manifest files for my application. and I have handlers for appCache events. I want to determine if the files are being downloaded for the first time or are being updated. because in case of updating them, I would like to prevent my application code from running, since refreshing the browser after updating my application.

my specific problem is that when the "check" events are fired, the application cache status is already "DOWNLOADING"

Does anyone know how to get applicationCache.status before any manifest or files are loaded?

in advance for any answer

window.applicationCache.addEventListener('checking', function (event) {
    console.log("Checking for updates.");
    console.log("inside checking event, appcache status : %s", applicationCache.status);
}, false);

window.applicationCache.addEventListener('updateready', function (e) {
    if (window.applicationCache.status == window.applicationCache.UPDATEREADY) {
        // Browser downloaded a new version of manifest files
        window.location.reload();
    }
}, false);

window.applicationCache.addEventListener('downloading', function (event) {
    appCommon.information("New version available", "Updating application files...", null, null);
}, false);

window.applicationCache.addEventListener('progress', function (event) {
    $("#informationModal").find(".modal-body").html("Updating application files... " + event.loaded.toString() + " of " + event.total.toString());
}, false);

window.applicationCache.addEventListener('cached', function (event) {
    $("#informationModal").find(".modal-body").html("Application up to date.");
    setTimeout(function () { $("#informationModal").find(".close").click(); }, 1000);
}, false);