jquery判断邮箱对错

<!DOCTYPE html>
<html >
<head>
    <meta charset="UTF-8">
    <title>检测Email地址格式是否正确</title>
     <script src="http://apps.bdimg.com/libs/jquery/1.10.2/jquery.min.js"></script>
</head>
<body>
    <input type="text" >
    <input type="submit" value="检测Email地址格式是否正确" class="is-email">

    <script type="text/javascript">
    $(".is-email").click(function(){
        var email = $("#emailname").val();
        if(email == ''){
              alert("请输入您的邮箱");
              return;
        }else if(email != "") {
            var reg = /^\w+((-\w+)|(\.\w+))*\@[A-Za-z0-9]+((\.|-)[A-Za-z0-9]+)*\.[A-Za-z0-9]+$/;
            isok= reg.test(email );
            if (!isok) {
                alert("邮箱格式不正确,请重新输入!");
                return false;
            }
        };
        alert("ok 输入正确");
    });
    </script>
</body>
</html>