function trim(s) {
  return s.replace(/^\s+|\s+$/, '');
}

function validateEmail(fld) {
	var valid = true;
	var tfld = trim(fld.value);                        // value of field with whitespace trimmed off
	var emailFilter = /^[^@]+@[^@.]+\.[^@]*\w\w$/ ;
	var illegalChars = /[\(\)\<\>\,\;\:\\\"\[\]]/ ;
	
	if (fld.value == "") {
		valid = false;
	}
	else if (!emailFilter.test(tfld)) {              //test email for illegal characters
		valid = false;
	}
	else if (fld.value.match(illegalChars)) {
		valid = false;
	}
	else {
		valid = true;
	}

	return valid;
}

function validate_form(form) {
	valid = true;

	if (form.surname.value == "") {
		alert ("请输入你的姓氏");
		form.surname.focus();
		valid = false;
	}
	else if (form.firstname.value == "") {
		alert ("请输入你的名字");
		form.firstname.focus();
		valid = false;
	}
	else if (form.salutation.selectedIndex == 0) {
		alert ("请输入你的称呼");
		form.salutation.focus();
		valid = false;
	}
	else if (!validateEmail(form.email)) {
		alert ("请输入你的电子邮箱");
		form.email.focus();
		form.email.select();
		valid = false;
	}
	else if (form.mobile.value == "") {
		alert ("请输入你的联络电话");
		form.mobile.focus();
		valid = false;
	}

	return valid;
}