Question

I have the javascript code below which disables an asp.net button during page postback. I also have a dropdownlist whose Autopostback property is set to true. Unfortunately, when i change the selectedItem in the dropdownlist, the button is disabled.

I want the Button disabled only when the page postback is caused by that same button, but not any other control on the page.

Some one please help on what change i should make to the code below to achieve this.

<script type="text/javascript">
    // Get a reference to the PageRequestManager.
    var prm = Sys.WebForms.PageRequestManager.getInstance();

    // Using that prm reference, hook _initializeRequest
    // and _endRequest, to run our code at the begin and end
    // of any async postbacks that occur.
    prm.add_initializeRequest(InitializeRequest);
    prm.add_endRequest(EndRequest);

    // Executed anytime an async postback occurs.
    function InitializeRequest(sender, args) {

        // Change the Container div's CSS class to .Progress.
        $get('Container').className = 'Progress';

        // Get a reference to the element that raised the postback,
        //   and disables it.
        $get(args._postBackElement.id).disabled = true;
    }

    // Executed when the async postback completes.
    function EndRequest(sender, args) {
        // Change the Container div's class back to .Normal.
        $get('Container').className = 'Normal';

        // Get a reference to the element that raised the postback
        //   which is completing, and enable it.
        $get(sender._postBackSettings.sourceElement.id).disabled = false;
    }                 
</script>

Answer 1

Well, you’re hooking into any asynchrous postback, sounds like you just want to hook into a particular button’s postback.

However, you could fix this with minimal code adjustment, just by checking the ID of the control which triggered the postback before disabling it.

if (args._postBackElement.id == idOfTheButton)
   $get(args._postBackElement.id).disabled = true;

Of course, if your button is a server-side button (asp:button), then you would need to either render out the client-id to the client from the server, or access it directly:

if (args._postBackElement.id == '<%= YourButton.ClientId %>')
   $get(args._postBackElement.id).disabled = true;

As i said, there are better solutions than this (like only hooking into the postback event of the button, not any postback event).

But nonetheless, this should solve your problem.