how to select dropdownmwnu list in bootstrap 4 code example

Example 1: bootstrap 4 dropdown

<div class="dropdown">
  <button class="btn btn-secondary dropdown-toggle" type="button" id="dropdownMenuButton" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
    Dropdown button
  </button>
  <div class="dropdown-menu" aria-labelledby="dropdownMenuButton">
    <a class="dropdown-item" href="#">Action</a>
    <a class="dropdown-item" href="#">Another action</a>
    <a class="dropdown-item" href="#">Something else here</a>
  </div>
</div>

Example 2: bootstrap 4 dropdown item list style

$(document).ready(function() {
  $(".dropdown-menu li a").click(function(e) {
    e.preventDefault();
    $(".dropdown-menu li").removeClass('activeTabLink');
    var activeAttr = $(this).parent('li').addClass('activeTabLink');
  });
});