var poll = document.pollForm;
poll.onsubmit = function() {
    var flag = false;
    for (i=0; i<poll.elements.length; i++) {
        if (poll.elements[i].checked) {
            flag = true;
        }
    }
    if (!flag) {
        alert(alertPoll);
        return false;
    }
    return true;
}