I try to pass the 'data-id' from the code below:
<a data-toggle="modal" data-id="10" class="passingID">
   <button type="button" class="btn btn-primary btn-sm" data-toggle="modal" data-target="#editkaryawan">
       <i class="fas fa-pencil-alt"></i> Edit</button>
</a>
To an input form values here:
<div class="modal-body">
    <form method="post" action="tambahkaryawan.php">
      <input type="hidden" class="form-control" name="idkl" id="idkl" value="">
    </form>
</div>
This is the jquery i use:
  <script>
    $(document).on("click", ".passingID", function () {
     var ids = $(this).data('id');
     $(".modal-body #idkl").val( ids );
    });
  </script>
 
     
     
    