Trying to submit form using ajax in codeigniter – Jquery ajax

I am trying to submit the form using ajax but it gives always error and data is not submitting into the database.
Please have a look at my code. I have searched about that but didn’t get any solution actually I am new in Codeigniter didn’t have much knowledge about that. I very thankful is someone helps me to solve this error thanks.

jQuery / AJAX Code:

 <script>


    $(document).ready(function(){
        $("#personal-info").submit(function(e){
            e.preventDefault();
            var fname = $("#fname").val();;
            var email_address= $("#email_address").val();
            var comment= $("#comment").val();
            $.ajax({
                type: "POST",
                url: '<?= site_url('Book/contact')?>',
                data: {fname:fname,email_address:email_address,comment:comment},
                success:function(data)
                {
                     Swal.fire({
                  position: 'top-end',
                  icon: 'success',
                  title: 'Message send successfuly',
                  showConfirmButton: false,
                  timer: 1500
                });
                },
                error:function()
                {
                    Swal.fire({
                  position: 'top-end',
                  icon: 'error',
                  title: 'Message Sending Fale Please try again',
                  showConfirmButton: false,
                  timer: 1500
                });
                }
            });
        });
    });
</script>

VIEW :

<div class="row">
                    <div class="col-lg-5 offset-lg-6 col-md-12">
                        <div class="section-title v2">
                            <h2>Write to us</h2>
                        </div>
                        <form id="personal-info" action="" method="post">
                            <div class="form-control-wrap">
                                <div id="message" class="alert alert-danger alert-dismissible fade"></div>
                                <div class="form-group">
                                    <input type="text" class="form-control" id="fname" placeholder="Name*" name="fname" required>
                                </div>
                                <div class="form-group">
                                    <input type="email" class="form-control" id="email_address" placeholder="email*" name="email" required>
                                </div>
                                <div class="form-group">
                                    <textarea class="form-control" rows="8" name="comment" id="comment" placeholder="Your Message" required></textarea>
                                </div>
                                <div class="form-group">
                                    <button type="submit" id="send_form" class="btn v7">Send Message</button>
                                </div>
                            </div>
                        </form>
                    </div>
                </div>

Controller :

 public function contact()
    {
         $data = array(
            'name' => $this->input->post('fname'),
            'emall' => $this->input->post('email'),
            'message' => $this->input->post('message'),
          
        );
          $this->db->insert('contact',$data);
           echo json_encode($data);
    }