ASP.NET, Showing Loading message while Postback

Question

I have an ASP.NET page which has an asp.net button control in it. When the user clicks on the button, the page will do some calculations and then close itself, but when I click on the button during post back, the page shows a blank screen. I want to show a loading message instead of this. I used javascript to show a div which was hidden intitially and shown when the user clicks the button, but when the post back happens, the screen becomes blank. Any idea how to show the loading messsage in this scenario?

Thanks in advance.

Answer 1

Basically, you can't using just postbacks. The browser draws the screen white while waiting for a response from the server. That message you set to show when the user clicks a button was the correct approach (so good work).

But the browser drew the screen white, thinking "Oh boy I'm about to get a response!" and then waited for longer than you think is appropriate.

The only thing you could try would be, in the response, make the very first thing to stream to the browser some sort of loading message that the browser can display while loading the rest (like the gmail loading screen). But personally, I think you could spend your time doing some other development.

You could try other techniques with AJAX though.

Answer 2

If you use Ajax to post back to the form asynchronously, you can use the UpdateProgress control. Here is a link to an article explaining how to implement the functionality:

How to make a Gmail-like loading indicator with ASP.NET Ajax

Answer 3

Do you really need to avoid ASP.NET ajax or JQuery?

If so: move the heavy processing into an invisible IFRAME. Action your form to the invisible IFRAME, or use javascript to set the location of the IFRAME.

Your 'loading' javascript will display fine. When the form inside the IFRAME completes it just needs to output some javascript to tell the 'parent' to go to location or refresh.