I think I understand HOW Javascript has to work in order to be O.K. for section 508. But I have been unable to find an answer to a related question: does my site need to work W
ADA 508 doesn't require you to have JavaScript. All you have to do is add a tag that explains that they can't log in without JavaScript enabled. Then when it is enabled, you should verify that the event handlers that are called have no problems on screen readers.
This site explains the javascript event handlers that work well with most screen readers: http://ada508.com/ OnClick and simple validation should be fine.
So in short...no, all content does not have to be accessible to readers without JavaScript as long as you have a tag on the page.