How to define an undefined return value from C# code behind, JS / JQuery

Question

This is a follow up using the code from my previous question:

Why wont js read text box values

My code behind methods are already displayed in that post.

My script works fine with the code behind but when I am trying to retrieve the return value I am getting a return value of "undefined".

The JS code is simple:

var answer  = PageMethods.saveCat(CategoryName, ParentID, CategoryID, CatChk);
window.alert(answer);

I have also tried:

windows.alert(String(answer));

but I keep getting an undefined value. I have searched around but have only been able to find solutions using a drawn out $.ajax syntax and was wondering is there a simple way to grab the string value returned by my web method similar to the code I am trying to get to work instead of writing 10 - 15 lines of code?

Thanks for the help.

Answer 1

Thanks to Karthik Ganesan's comment I was able to get on the right track using this link: mindfiresolutions.com/Using-PageMethods-in-ASPNET-2467.php

My resulting code was:

PageMethods.saveCat(CategoryName, ParentID, CategoryID, CatChk, onSuccess, onFailure);
               function onSuccess(result)
               {
                   alert(result);
               }
               function onFailure(result)
               {
                   alert("There was an error saving the category.");
               }

I am posting this hoping it helps out other newbies to JS.