What is the alternative to `alert` in metro apps?

Question

I created my first app on Windows 8 vs 2012 and it runs and works fine. But when I try to say \"helloworld\" from JavaScript like this:

alert(\"Hello World\         


        

Answer 1

javascript：

 (function () {

  window.alert = function (message) {
      window.external.notify( message);
  }
//do some test
alert("a");
alert("b");
alert("c");
window.setInterval(function () {
    alert("e");
    alert("f");
}, 5000);
window.setInterval(function () { 
    alert("d");
    alert("2");
}, 10000);
 })();

C#:

  //register ScriptNotify event
  webView2.ScriptNotify += webView2_ScriptNotify;

async void webView2_ScriptNotify(object sender, NotifyEventArgs e)
    {
        MSG.Alert(e.Value);
    }


public class MSG
{
    static List messages = new List();


    public static void Alert(string message)
    {

        messages.Add(message);
        if (messages.Count == 1)
        {
              Show(messages.First());
        }

    }

    private static async Task Show(string message)
    {
        MessageDialog md = new MessageDialog(message, "Title");

        md.Commands.Add(
           new UICommand("OK", new UICommandInvokedHandler((cmd) =>
           {
               messages.RemoveAt(0);

           })));



        await md.ShowAsync();

        while (messages.Count > 0)
        {

            await Show(messages.First());
        }

    }

}