BS4 Modal - ajax

Form Message from modal win by ajax req

<button 
type="button"
class="btn btn-outline-primary" 
data-toggle="modal" 
data-target="#primaryWin"
data-whatever="@fName">Primary</button>

<div class="modal fade" id="primaryWin" tabindex="-1" role="dialog" aria-labelledby="primaryWinLabel" aria-hidden="true">
    <div class="modal-dialog" role="document">
        <div class="modal-content">
            <div class="modal-header">
                <h5 class="modal-title" id="primaryWinLabel">New message</h5>
                <button type="button" class="close" data-dismiss="modal" aria-label="Close">
                    <span aria-hidden="true">&times;</span>
                </button>
            </div>
            <div class="modal-body">

                <!-- FORM -->
                <form method="post" action="server.php" id="formMsg">
                    <div class="form-group">
                        <label for="recipient-name" class="col-form-label">Recipient:</label>
                        <input type="text" class="form-control" id="recipient-name">
                    </div>
                    <div class="form-group">
                        <label for="message-text" class="col-form-label">Message:</label>
                        <textarea class="form-control" id="message-text"></textarea>
                    </div>
                </form>
                <!-- FORM -->
                
            </div>
            <div class="modal-footer">
                <button type="button" class="btn btn-secondary" data-dismiss="modal">Close</button>
                <button type="button" id="btnSbt" class="btn btn-primary">Send message</button>
            </div>
        </div>
    </div>
</div>

<script src="js/jquery-3.3.1.min.js"></script>
<script src="js/popper.min.js"></script>
<script src="js/bootstrap.min.js"></script>
<script>
    // Modal Win
    $('#primaryWin').on('show.bs.modal', function (event) {
    var button = $(event.relatedTarget); // Button that triggered the modal
    var recipient = button.data('whatever') // Extract info from data-* attributes
    // If necessary, you could initiate an AJAX request here (and then do the updating in a callback).
    // Update the modal's content. We'll use jQuery here, but you could use a data binding library or other methods instead.
    var modal = $(this);
    modal.find('.modal-title').text('New message to ' + recipient);
    modal.find('.modal-body input').val(recipient);

    // On submit
    $('#formMsg').on('submit',function(event){
        $.ajax({
            url: 'server.php',
            context: document.body
        }).done(function(data) {
            alert(data);
        });
        event.preventDefault();
    });

    // on click submit
    $('#btnSbt').click(function () {
        $('#formMsg').submit();
    });
});
</script>