there are several javascript libraries avaliable to do an AJAX request to a server.- DojoKit- Rico- Prototype- Yahoo! UI (YUI)If you're interested in YUI and AJAX, you'll want to take a look at the Connection Manager utility which will enable you to make XHR (aka AJAX) requests. Documentation and examples can be found on the YUI site.If you're mainly concerned with integrating Ruby on Rails and Javascript, I found Dan Webb's site informative for that particular reason.
developer.yahoo.com