Just by adding this small JavaScript module to the end of your web pages, you get your form's submissions intercepted and, instead of sending request to the server in the usual way, they are done asynchronously and in an AJAX-style smooth way.
As long as it is a client-side library it will work with any server technology: ASP.NET, PHP, JSP, Classic ASP... and even with local HTM files.
I've included extensibility so that you can add easily your own progress indicators (several included) and show error messages the way you prefer (by default it shows an alert).
It's transparent to your server code and could be used to add AJAX capabilities to some applications without writting a single line of code.
Documentation is included.