Learning Javascript & AJAX
invisible: I would honestly recommend reading through some of the code and trying to figure out what it's doing.  Find a function in jQuery you use all of the time and figure out how it accomplishes it's goal.  Also, John Resig has a decent (albeit may miss some of the points you'll need) tutorial application: http://ejohn.org/apps/learn/(Edit: I'd also recommend any time you need anything, look to see if it exists first regardless of how small it is. And http://www.w3schools.com/jsref/ will help you enormously.)As far as AJAX, I'd recommend to just understand how it SHOULD work.  Understand what the Xhrconn object you have should contain and what you should be able to retrieve from the "raw" object if you need to do so.  Trying to understand where it fails in IE, Firefox, Safari, and Opera is overkill (there are so many little bugs!).