JS(JavaScript)判断邮箱格式

<script type="text/javascript">
function ischeckemail(){
var email = document.getElementById("email").value;
            $("#emailmsg").empty();
            if (email != "") {
            var reg = /^\w+((-\w+)|(\.\w+))*\@[A-Za-z0-9]+((\.|-)[A-Za-z0-9]+)*\.[A-Za-z0-9]+$/;
                isok= reg.test(email );
                if (!isok) {
                    $("#emailmsg").append("邮箱错误");
                    document.getElementById("emailname").focus();
                    return false;
                }
            };
}
</script>