I am a novice-intermediate programmer taking a stab at AJAX. While reading up on JavaScript I found it curious that most of the examples I\'ve been drawing on use PHP for su
You can use something like Google Gears to produce JS applications which are capable of storing data in a local cache or database. You can't read or write arbitrary areas of the disk though. (This was written in 2009 - Google Gears is now deprecated)
These days, you should be looking at the local storage capabilities provided by HTML5