function checkForm() {
    thisform = document.contact;
    if (thisform.name.value == "") {
        alert("Please fill in your name.");
        return false;
    }
    if (thisform.email.value == "") {
        alert("Please fill in a valid e-mail address.");
        return false;
    }
    if (thisform.comments.value == "") {
        alert("Please fill your comment or question.");
        return false;
    }
    return true;
}