Dapatkan Nilai Bidang Jenis Tersembunyi

<input type="hidden" id="foo" name="zyx" value="bar" />

alert($('input#foo').val());
alert($('input[name=zyx]').val());
alert($('input[type=hidden]').val());
alert($(':hidden#foo').val());
alert($('input:hidden[name=zyx]').val());
Thoughtful Tapir