<p>Is there any way to find out if the user pressed the delete key or dot? It has the same keycode in FireFox.</p>

According to
Detecting keystrokes
, it is possible, provided that:
you search for the keyCode (
8
for delete) onkeydown/up, and
ignore both onkeypress and charCode (Especially if you consider the fact that IE does not fire keypressed event, only key up/down).