JSFiddle - React, Tailwind, and code Playground

HTML

<link rel="stylesheet" href="//netdna.bootstrapcdn.com/bootstrap/3.0.2/css/bootstrap.min.css">
<script src="//netdna.bootstrapcdn.com/bootstrap/3.0.2/js/bootstrap.min.js"></script>
<!-- Button trigger modal -->
<button class="btn btn-primary btn-lg launch-modal" data-toggle="modal" data-target="#myModal1">
  Launch modal 1
</button>

<button class="btn btn-primary btn-lg launch-modal" data-toggle="modal" data-target="#myModal2">
  Launch modal 2
</button>





<!-- Modal 1 -->
<div class="modal fade" id="myModal1" tabindex="-1" role="dialog" aria-labelledby="myModalLabel" aria-hidden="true">
  <div class="modal-dialog">
    <div class="modal-content">
      <div class="modal-header">
        <button type="button" class="close" data-dismiss="modal" aria-hidden="true">&times;</button>
        <h4 class="modal-title" id="myModalLabel">Modal title</h4>
      </div>
      <div class="modal-body">
        <textarea id="textareaID1" class="form-control"></textarea>
      </div>
      <div class="modal-footer">
        <button type="button" class="btn btn-default" data-dismiss="modal">Close</button>
        <button type="button" class="btn btn-primary">Save changes</button>
      </div>
    </div><!-- /.modal-content -->
  </div><!-- /.modal-dialog -->
</div><!-- /.modal -->


<!-- Modal 2 -->
<div class="modal fade" id="myModal2" tabindex="-1" role="dialog" aria-labelledby="myModalLabel" aria-hidden="true">
  <div class="modal-dialog">
    <div class="modal-content">
      <div class="modal-header">
        <button type="button" class="close" data-dismiss="modal" aria-hidden="true">&times;</button>
        <h4 class="modal-title" id="myModalLabel">Modal title</h4>
      </div>
      <div class="modal-body">
        <textarea id="textareaID2" class="form-control"></textarea>
      </div>
      <div class="modal-footer">
        <button type="button" class="btn btn-default" data-dismiss="modal">Close</button>
        <button type="button" class="btn btn-primary">Save...

CSS

.launch-modal {
    margin: 20px;
}

JavaScript

/*$('#myModal1').on('shown.bs.modal', function () {
    $('#textareaID1').focus();
    
})
$('#myModal2').on('shown.bs.modal', function () {
    $('#textareaID2').focus();
})
*/
$(document).on('open', '#myModal1', function () {
    $('input').attr('tabindex', "-1");
    $('.modal-form input').each(function(index, input) {
        input.tabIndex = index + 1;
        $('.modal-form').find('input select textarea').first().focus();
    });
});

$(document).on('close', '.remodal', function () {
    $('input').each(function(index, input) {
        input.tabIndex = index + 1;
        
     });
});

$('.modal-form').find('input select textarea').first().focus();