How can I hook up to Excel events in Javascript

Question

In a client-side web application, I would like to:

1. open an Excel spreadsheet,
2. export some application data to Excel,
3. allow the user to work with it, and
4. when they are done, read the (potentially changed) data back into my application.

I would like the user to have a fluid experience and detect when they are done with excel by hooking up to the BeforeClose event, but I find that I am unable to hook up to Excel's events in javascript/HTML.

function BeforeCloseEventHandler(cancel) {
    // TODO: read values from spreadsheet
    alert("Closing...");
}

function openExcel() {
    var excel = new ActiveXObject("Excel.Application");
    var workbook = excel.Workbooks.Add();
    var worksheet = workbook.Worksheets(1);
    worksheet.Cells(1, 1).Value = "First Cell";
    worksheet.Cells(1, 2).Value = "Second Cell";
    workbook.BeforeClose = BeforeCloseEventHandler;  // THIS DOESN'T WORK
    excel.Visible = true;
    excel.UserControl = true;
}

Does anyone have any suggestions?

Answer 1

After doing some research, I have discovered that I cannot hook up events to dynamic ActiveX objects (i.e., the ones that are created by the new ActiveXObject constructor) in javascript.

One idea is that I create a wrapper Windows Form user control that would be hosted inside of an <object> tag in the web app. The user control would call Excel and receive events, and raise events back to javascript, which I could hook up to using the <script for="..." event="..."> mechanism. Not sure that this will work, but I will try it.

Even if it does work, I am not particularly happy about this solution. There are too many layers--the javascript is being called from a silverlight control meaning that my data has to cross 3 boundaries there and back: Silverlight -> Javascript -> Hosted Winform User Control -> Excel.

It would be nice to eliminate some of these boundaries.