[Javascript] Memory leaks?

[scott at randomchaos.com (Scott Reynen)]

I have a few AJAX applications, which work fine in IE, Firefox, and  
Safari, pinging the server every few seconds for new data.  I've  
noticed that if I leave one of these applications open overnight in  
Safari (haven't tested this in anything else yet), the key event  
handling will slow to a crawl by morning and it will only register  
that I've typed something a second or two after I actually press the  
key.  When I first open the application, such typing will register  
immediately.  Even if I reload the page after this happens, it will  
still be slow until I actually restart the whole browser.

I'm not clear on what's causing this, but it seems like a memory  
leak.  Here are two applications that both seem to cause this problem:

http://randomchaos.com/games/fastr/js/chat.js
http://randomchaos.com/games/fastr/js/group.js

The both involve typing in a text input, and they both take specific  
actions on the return/enter (13) keypress.  Unfortunately, you won't  
be able to experience the problem yourself with registering and  
leaving it open for several hours.  I'm sure there are a hundred  
problems with this code, as I'm largely self-taught in JavaScript.   
I'm specifically interested in the problem I described above, and  
would appreciate any suggestions in preventing such a gradual  
slowdown of the event handling.

Peace,
Scott