function isValid()
{
	var userName = document.getElementById('pwtypev');
	var pwd		 = document.getElementById('pwpwd');
	var gdcode	 = document.getElementById('gdcode');
	
	if(userName.value == "")
	{
		alert('请输入用户名！');
		userName.focus();
		return false;
	}
    else if(pwd.value == "")
	{
		alert('请输入密码！');
		pwd.focus();
		return false;
	}
	else if(gdcode.value == "")
	{
		alert('请输入验证码！');
		gdcode.focus();
		return false;
	}
	
	return true;
}