How to add JavaScript function before request or after request for ACT Update Panel?

PageRequestManager

                Sys.WebForms.PageRequestManager.getInstance().add_beginRequest(BeginRequestHandler);

                Sys.WebForms.PageRequestManager.getInstance().add_endRequest(EndRequestHandler);

                function BeginRequestHandler(sender, args)

                {

                     var elem = args.get_postBackElement();

                     ActivateAlertDiv('visible', 'AlertDiv', elem.value + ' processing...');

                }

                function EndRequestHandler(sender, args)

                {

                     ActivateAlertDiv('hidden', 'AlertDiv', '');

                }

 http://msdn.microsoft.com/en-us/library/bb311028.aspx

In ASP.NET, ENTER key on a FORM with a single Input Field, will automatically SUBMIT.

This happens in IE, Chrome, but not in Firefox.

Solution: add another hidden input field. Such as:

<div style="display: none">

    <input type="text" name="hiddenText" />

</div>

Reason:

Because IE and Chrome following HTML2.0 Specification exactly.

According to HTML2.0 Specification, 8.2. Form Submission:

When there is only one single-line text input field in a form, the

   user agent should accept Enter in that field as a request to submit

   the form.

http://tools.ietf.org/html/rfc1866#section-8.2