Can't run javascript alerts in universal app's webview at payment gateway

Question

I am integrating payment gateway in my universal windows app where I open the URL in a webview. However, webview can't seem to display javascript alert messages or popups. I read online that I need to add url's of website in package manifest to enable Scriptnotify event to run but given it's a payment gateway, it's not feasible to add url's for all bank websites. Is there a way to handle this ?

Also I am handling the ScriptNotify event as this, but this seems to be partially correct.

private async  void MyWebView_ScriptNotify(object sender, NotifyEventArgs e)
    {
        Windows.UI.Popups.MessageDialog dialog = new Windows.UI.Popups.MessageDialog(e.Value);

        await dialog.ShowAsync(); 
    }


private async void MyWebView_NavigationCompleted(WebView sender, WebViewNavigationCompletedEventArgs args)
    {
        string result = await this.MyWebView.InvokeScriptAsync("eval", new string[] { "window.alert = function (AlertMessage) {window.external.notify(AlertMessage)}" });

    }

Answer 1

After banging my head for a week or two, finally found the solution, following are the necessary event handlers :

private async void MyWebView_NavigationCompleted(WebView sender, WebViewNavigationCompletedEventArgs args)
    {
            string result = await this.MyWebView.InvokeScriptAsync("eval", new string[] { "window.confirm = function (ConfirmMessage) {window.external.notify(ConfirmMessage)}" });
    }


private async void MyWebView_ScriptNotify(object sender, NotifyEventArgs e)
    {

            Windows.UI.Popups.MessageDialog dialog = new Windows.UI.Popups.MessageDialog(e.Value);
            dialog.Commands.Add(new UICommand("Yes"));
            dialog.Commands.Add(new UICommand("No"));

            // Set the command that will be invoked by default
            dialog.DefaultCommandIndex = 0;

            // Set the command to be invoked when escape is pressed
            dialog.CancelCommandIndex = 1;

            var result = await dialog.ShowAsync();

            if (result.Label.Equals("Yes"))
            {
                string res = await MyWebView.InvokeScriptAsync("eval", new string[] { "window.confirm = function (ConfirmMessage) {return true}" });
            }
            else
            {
                string res = await MyWebView.InvokeScriptAsync("eval", new string[] { "window.confirm = function (ConfirmMessage) {return false}" });
            }
    }