Bootstrap-4 Buttons with dropdowns Selected value not display

I'm used bootstrap-4 Buttons with drop downs I have some issue selected value not display for this drop down? I want to know how to set of the currency name when the selected value correctly, My code is something wrong, Getting one time all of value for this,You can understand that issue, please look at snippet

$(".dropdown-menu ").click(function(){

  $(this).parents(".input-group-btn").find('.btn').text($(this).text());
 

});

<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-beta.2/css/bootstrap.min.css" integrity="sha384-PsH8R72JQ3SOdhVi3uxftmaW6Vc51MKb0q5P2rRUpPvrszuE4W1povHYgTpBfshb" crossorigin="anonymous">
<script src="https://code.jquery.com/jquery-3.2.1.slim.min.js" integrity="sha384-KJ3o2DKtIkvYIK3UENzmM7KCkRr/rE9/Qpg6aAZGJwFDMVNA/GpGFF93hXpG5KkN" crossorigin="anonymous"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.12.3/umd/popper.min.js" integrity="sha384-vFJXuSJphROIrBnz7yo7oB41mKfc8JzQZiCq4NCceLEaO4IHwicKwpJf9c9IpFgh" crossorigin="anonymous"></script>
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-beta.2/js/bootstrap.min.js" integrity="sha384-alpBpkh1PFOepccYVYDB4do5UnbKysX5WZXm3XxPqe5iKTfUKjNkCk9SaVuEZflJ" crossorigin="anonymous"></script>
<div class="row">
  <div class="col-lg-6">
    <div class="input-group">
      <div class="input-group-btn">
        <button type="button" class="btn btn-secondary dropdown-toggle" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
         Currency
        </button>
        <div class="dropdown-menu">
          <a class="dropdown-item" href="#">USD</a>
          <a class="dropdown-item" href="#">AUS</a>
       
        </div>
      </div>
      <input type="text" class="form-control" aria-label="Text input with dropdown button">
    </div>
  </div>
 
</div>

Solution

I resolved the my problem Solution 01
button work like a select box , I change my script

<script>

            $('.dropdown-menu a').on('click', function(){    
        $('.dropdown-toggle').html($(this).html());    
    })
        </script>

now its work for me

	$('.dropdown-menu a').on('click', function(){    
    $('.dropdown-toggle').html($(this).html());    
})

<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-beta.2/css/bootstrap.min.css" integrity="sha384-PsH8R72JQ3SOdhVi3uxftmaW6Vc51MKb0q5P2rRUpPvrszuE4W1povHYgTpBfshb" crossorigin="anonymous">
<script src="https://code.jquery.com/jquery-3.2.1.slim.min.js" integrity="sha384-KJ3o2DKtIkvYIK3UENzmM7KCkRr/rE9/Qpg6aAZGJwFDMVNA/GpGFF93hXpG5KkN" crossorigin="anonymous"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.12.3/umd/popper.min.js" integrity="sha384-vFJXuSJphROIrBnz7yo7oB41mKfc8JzQZiCq4NCceLEaO4IHwicKwpJf9c9IpFgh" crossorigin="anonymous"></script>
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-beta.2/js/bootstrap.min.js" integrity="sha384-alpBpkh1PFOepccYVYDB4do5UnbKysX5WZXm3XxPqe5iKTfUKjNkCk9SaVuEZflJ" crossorigin="anonymous"></script>
<div class="row">
  <div class="col-lg-6">
    <div class="input-group">
      <div class="input-group-btn">
        <button type="button" class="btn btn-secondary dropdown-toggle" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
         Currency
        </button>
        <div class="dropdown-menu">
          <a class="dropdown-item" href="#">USD</a>
          <a class="dropdown-item" href="#">AUS</a>
       
        </div>
      </div>
      <input type="text" class="form-control" aria-label="Text input with dropdown button">
    </div>
  </div>
 
</div>

Solution-02 Script

        $(".dropdown-menu a ").click(function(){

  $(this).parents(".input-group-btn").find('.btn').text($(this).text());


});

$(".dropdown-menu a ").click(function(){

  $(this).parents(".input-group-btn").find('.btn').text($(this).text());
 

});

   <link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-beta.2/css/bootstrap.min.css" integrity="sha384-PsH8R72JQ3SOdhVi3uxftmaW6Vc51MKb0q5P2rRUpPvrszuE4W1povHYgTpBfshb" crossorigin="anonymous">
    <script src="https://code.jquery.com/jquery-3.2.1.slim.min.js" integrity="sha384-KJ3o2DKtIkvYIK3UENzmM7KCkRr/rE9/Qpg6aAZGJwFDMVNA/GpGFF93hXpG5KkN" crossorigin="anonymous"></script>
    <script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.12.3/umd/popper.min.js" integrity="sha384-vFJXuSJphROIrBnz7yo7oB41mKfc8JzQZiCq4NCceLEaO4IHwicKwpJf9c9IpFgh" crossorigin="anonymous"></script>
    <script src="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-beta.2/js/bootstrap.min.js" integrity="sha384-alpBpkh1PFOepccYVYDB4do5UnbKysX5WZXm3XxPqe5iKTfUKjNkCk9SaVuEZflJ" crossorigin="anonymous"></script>
    <div class="row">
      <div class="col-lg-6">
        <div class="input-group">
          <div class="input-group-btn">
            <button type="button" class="btn btn-secondary dropdown-toggle" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
             Currency
            </button>
            <div class="dropdown-menu">
              <a class="dropdown-item" href="#">USD</a>
              <a class="dropdown-item" href="#">AUS</a>
           
            </div>
          </div>
          <input type="text" class="form-control" aria-label="Text input with dropdown button">
        </div>
      </div>
     
    </div>