Asp.NET MVC AjaxOptions OnSuccess fires.. too early?

Question

I'd like to use the OnSuccess option of AjaxOptions passed as Ajax.BeginForm argument to "do something" once the response is completely received and DOM updated. As far as I can undestand from MSDN, this is what this option do.

In my application, OnSuccess script fires too early, immediately after the request is sent. I put to sleep the thread for a while, to better see the result. I supposed to see the OnSuccess script (an alert) fired after that sleep time, say, 2 seconds. I use Firebug to see what's happening under the hood, and all I see is: I click the button (submit inside the ajax form), alert is shown (2 seconds before expected), after 2 seconds firebug shows the request-response and nothing more happens.

Where I'm wrong?

Thanks in advance, mt

Some sample code, as correctly asked (I started a blank new solution using Asp.NET MVC template in VS):

Home/Index view:

<asp:Content ID="indexContent" ContentPlaceHolderID="MainContent" runat="server">
<div id="divPlaceholder">
<% 
    using (Ajax.BeginForm("DoLongTask", "Home", 
    new AjaxOptions() {
        UpdateTargetId = "divPlaceholder", 
        InsertionMode = InsertionMode.Replace,
        OnSuccess = "alert('onsuccess fired')"
    })) 
{
%>
<input type="submit" value="button" />
<% } %>
</div>
</asp:Content>

HomeController

public ActionResult DoLongTask()
{
    if (Request.IsAjaxRequest())
    {
        System.Threading.Thread.Sleep(2000);
        return View();
    }
    else
    {
        throw new NotSupportedException();
    }
}

I think this is enough to reproduce the behavior. An empty partial view can be used as DoLongTask view.

Answer 1

Not sure how helpful this will be but I am looking at doing something like this at the moment and have found if you call out to a function within the OnSucess then it will happen after the action method, for example:

using (Ajax.BeginForm("DoLongTask", "Home", 
    new AjaxOptions() {
        UpdateTargetId = "divPlaceholder", 
        InsertionMode = InsertionMode.Replace,
        OnSuccess = "function() { alert('onsuccess fired'); }"
    }))