Submitting a form by pressing enter without a submit button

Well I am trying to submit a form by pressing enter but not displaying a submit button. I don't want to get into JavaScript if possible since I want everything to work on all browsers (the only JS way I know is with events).

Right now the form looks like this:

<form name="loginBox" target="#here" method="post">
    <input name="username" type="text" /><br />
    <input name="password" type="password" />
    <input type="submit" style="height: 0px; width: 0px; border: none; padding: 0px;" hidefocus="true" />
</form>

Which works pretty well. The submit button works when the user presses enter, and the button doesn't show in Firefox, IE, Safari, Opera and Chrome. However, I still don't like the solution since it is hard to know whether it will work on all platforms with all browsers.

Can anyone suggest a better method? Or is this about as good as it gets?

Try:

<input type="submit" style="position: absolute; left: -9999px"/>

That will push the button waaay to the left, out of the screen. The nice thing with this is, you'd get graceful degradation when CSS is disabled.

Update - Workaround for IE7

As suggested by Bryan Downing + with tabindex to prevent tab reach this button (by Ates Goral):

<input type="submit" 
       style="position: absolute; left: -9999px; width: 1px; height: 1px;"
       tabindex="-1" />

I think you should go the Javascript route, or at least I would:

<script type="text/javascript">
// Using jQuery.

$(function() {
    $('form').each(function() {
        $(this).find('input').keypress(function(e) {
            // Enter pressed?
            if(e.which == 10 || e.which == 13) {
                this.form.submit();
            }
        });

        $(this).find('input[type=submit]').hide();
    });
});
</script>


<form name="loginBox" target="#here" method="post">
    <input name="username" type="text" /><br />
    <input name="password" type="password" />
    <input type="submit" />
</form>

Have you tried this ?

<input type="submit" style="visibility: hidden;" />

Since most browsers understand visibility:hidden and it doesn't really work like display:none, I'm guessing that it should be fine, though. Haven't really tested it myself, so CMIIW.