Bootstrap 3 jquery event for active tab change

$('a[data-toggle="tab"]').on('shown.bs.tab', function (e) {
  var target = $(e.target).attr("href") // activated tab
  alert(target);
});
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.6/js/bootstrap.min.js"></script>
<link href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.6/css/bootstrap.min.css" rel="stylesheet"/>

<ul id="myTab" class="nav nav-tabs">
  <li class="active"><a href="#home" data-toggle="tab">Home</a></li>
  <li class=""><a href="#profile" data-toggle="tab">Profile</a></li>
</ul>
<div id="myTabContent" class="tab-content">
  <div class="tab-pane fade active in" id="home">
    home tab!
  </div>
  <div class="tab-pane fade" id="profile">
    profile tab!
  </div>
</div>

$(function () {
    $('#myTab a:last').tab('show');
});

$('a[data-toggle="tab"]').on('shown.bs.tab', function (e) {
    var target = $(e.target).attr("href");
    if ((target == '#messages')) {
        alert('ok');
    } else {
        alert('not ok');
    }
});

the problem is that attr('href') is never empty.

Or to compare the #id = "#some value" and then call the ajax.