'Twas brillig, and the slithy toves did gyre and gimble in the wabe

It's possible (though unlikely) that Javascript is being used to do a client-side password hash, rather than sending the password in the raw to the server. However, since both the Kindle and the Wii support Javascript enough to do that, there's absolutely no excuse to not still support submitting the form in a normal way; it's just an explanation of why there is a plausible explanation of Javascript being involved at all.