function check_exist() {
            
            var email = $(‘#email‘).val().Trim();
            url = "/Account/Exist";
            $.post(url, { email: email }, function (result) {
                if (result == "1") {
                    $(‘#email_error‘).html("该邮箱已经被注册!");
                    return false;
                }
                else if (result == "0")
                    
                    $(‘#email_error‘).html("");

            });
            return true;


        }

 function regist() {
            if (!check_exist())
                return false;
            if (!check_pass())
                return false;
             ...........
}