AJAX Script in VS 2008
JavaScript code overall isn't that difficult to write. It may sometimes be hard to come up with a particular task, but it isn't that hard to write. It's hard to get syntatically correct, even with all of the features VS 2008 has to offer. VS 2008 has a lot of nice features to help prevent this, but sometimes it's hard to see that something's missing, especially since running an ASP.NET AJAX application doesn't tell you that your script is missing a comma or period, or a variable name is wrong.
That is the difficulty as it is now with JavaScript, and it's still there in VS 2008, so be prepared as you develop with AJAX to go through your script with a fine tooth comb, looking for green squiggly lines that an error occurred (if those lines appear at all).
The sign that something's wrong with your script usually is that a component's undefined, and can't be instantiated or used. I had this happen as a weird error occurred whenever I ran a script that my component was undefined, even though it was downloaded. It was simply a syntax issue.