JavaScript listener, "keypress" doesn't detect backspace?
KeyPress event is invoked only for character (printable) keys, KeyDown event is raised for all including nonprintable such as Control, Shift, Alt, BackSpace, etc.
UPDATE:
The keypress event is fired when a key is pressed down and that key normally produces a character value
Reference.
Try keydown instead of keypress.
The keyboard events occur in this order: keydown, keyup, keypress
The problem with backspace probably is, that the browser will navigate back on keyup and thus your page will not see the keypress event.