function isText(str) {
	return (str != null && str != "");
}

function isValidEmail(str) {
	var filter  = /^([a-zA-Z0-9_\.\-])+\@(([a-zA-Z0-9\-])+\.)+([a-zA-Z0-9]{2,4})$/;
	return (filter.test(str));
}

function validate_cf(which) {
	/* check e-mail */
	var err1 = "";
	if (!isValidEmail(which.cf_email.value)) {
		err1 += "e-mails must be in the format "name@domain.com"";
	}
	var cf_error1 = document.getElementById("cf_error1");
	if (cf_error1) {
		cf_error1.innerHTML = err1;
	}
	/* check subject */
	var err2 = "";
	if (!isText(which.cf_subj.value)) {
		err2 += "please select this required field";
	}
	var cf_error2 = document.getElementById("cf_error2");
	if (cf_error2) {
		cf_error2.innerHTML = err2;
	}
	return (err1 == "" && err2 == "");
}

function validate_cnf(which) {
	var err = "";
	if (!isValidEmail(which.cnf_email.value)) {
		err += "e-mails must be in the format "name@domain.com"";
	}
	if (err != "") {
		var cnf_error = document.getElementById("cnf_error");
		if (cnf_error) {
			cnf_error.innerHTML = err;
		}
		return false;
	}
	return true;
}