Script error บนทุก browser IOS และบน Safari เป็นเพราะอะไรคะ

               <script>            
                    function showone() {
                        $(".one").toggle();
                        $(".two").hide();
                    }
                    function showtwo() {
                        $(".one").hide();
                        $(".two").toggle();
                    }
                </script>


<button  onclick="showaddtwo()" style="color: #fff; background-color: #001654; border: 0px; border-radius: 15px; padding: 0px 30px; font-size: 100%;"> ถัดไป <i class="fa fa-chevron-right" aria-hidden="true" style="padding-left: 10px; "></i></button>

<div class="wrapper" >
    <form method="post" id="comment-form-xs" >
 

    <button class="center" id='btnValidate' type="submit" style="color: #fff; background-color: #001654; border: 0px; border-radius: 20px; padding: 0px 30px; font-size: 100%;"> เสร็จสิ้น </button>

    </form>
</div>

<script type="text/javascript">
$(document).ready(function() {  
    
    // submit form using $.ajax() method
    
    $('#comment-form-xs').submit(function(e){
        
        e.preventDefault(); // Prevent Default Submission
        
        $.ajax({
            url: 'submit_comment.php',
            type: 'POST',
            data: $(this).serialize() // it will serialize the form data
        })
        .done(function(data){
            $('#form-content-xs').fadeOut('slow', function(){
                $('#form-content-xs').fadeIn('slow').html(data);
            });
        })
        .fail(function(){
            alert('Ajax Submit Failed ...');    
        });
    });
});
</script>