A nearly universal problem in ASP.NET is handling multiple postbacks. There are various server-side and client-side solutions to deal with this, but these solutions can only be understood once you already have the domain knowledge to solve the problem yourself. You then end up repeating the pattern in every project.

Well, programming is about not repeating yourself and automating repetitive tasks. So I've released a reusable abstraction to handle multiple postbacks on the client-side. Because it's a client-side solution, it will only work for browsers with JavaScript enabled, but that's by far the most common case.

AspQ

AspQ is a small JavaScript object that hooks into the ASP.NET JS standard and AJAX runtimes. It basically queues all sync and async postback requests so they don't interfere with one another, and applies the updates in event order. I believe this option provides a superior user experience to simply preventing a submit until the previous postback has completed, because the user can still operate on the UI while they wait.

There have been quite a few incarnations of this idea in the wild, but I've found them all lacking. Either they didn't work for LinkButtons, or they didn't work with Master pages, or they didn't handle sync postbacks. AspQ should do them all.

So go ahead and download AspQ.js from the repository and save it in your site's script directory. You then have a choice of the following two methods to use it.

Method 1

Just include the JS in your pages:

<script type="text/javascript" src="/path/to/AspQ.js"></script>

override protected void OnInit(EventArgs e) { ... // register form submission script this.ClientScript.RegisterOnSubmitStatement(GetType(), "PreventDuplicateSubmits", "return AspQ.submit(this);"); ... }

Method 2

And place the following server-side code in your OnInit method of the System.Web.UI.Page:

This method makes only server-side changes using similar changes to the OnInit method:

override protected void OnInit(EventArgs e) { ... // include script site-wide var script = new HtmlGenericControl("script"); script.Attributes.Add("type", "text/javascript"); script.Attributes.Add("src", "/path/to/AspQ.js"); this.Header.Controls.Add(script); // register form submission script this.ClientScript.RegisterOnSubmitStatement(GetType(), "PreventDuplicateSubmits", "return AspQ.submit(this);"); ... }

AspQ is simple to setup and seems adequate for most purposes. If you have a use case that it doesn't handle, please let me know!

It's released under the LGPL, which is my default OSS license, but I'm open to discussion on the issue since the LGPL may not be appropriate for a JavaScript library.

Edit: here's a demo showing a simple counter. Press the +/- buttons as many times and as fast as you like, the updates will all happen and in the proper order.