PostMessage not working in IE

Question

I am trying to post messages from my pdf document to the web browser.  I have the following code snippet below.  I am receiving the alert from the pdf file in all browsers.  I am not getting the postMessage back in IE but I am in Chrome.
function onMessageFunc(messageArray)
        app.alert('incoming message: ' + messageArray[0]);
        try
            this.hostContainer.postMessage(["echo: " + messageArray[0]]);
        catch (e) {
            app.alert(e.message);

Answer 1

Acrobat JavaScript Overview:
PDF documents have great versatility since they can be displayed both within the Acrobat software as well as a web browser. Therefore, it is important to be aware of the differences between JavaScript used in a PDF file and JavaScript used in a web page:
JavaScript in a PDF file does not have access to objects within an HTML page. Similarly, JavaScript in a web page cannot access objects within a PDF file.
In HTML, JavaScript is able to manipulate such objects as Window. JavaScript for Acrobat cannot access this particular object but it can manipulate PDF-specific objects.