Как отследить изменившееся значение sessionStorage и поместить в переменную?

function onSampleResized(e) { 
  var $table = $(e.currentTarget); 
  console.clear(); 
  $table.find('th').each(function(i) { 
    console.log(`column: ${i}; width: ${$(this).width()}`); 
  }); 
} 
$("#flex").colResizable({ 
  liveDrag: true, 
  resizeMode: 'flex', 
  postbackSafe: true, 
  onResize: onSampleResized 
});

<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css"> 
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script> 
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/js/bootstrap.min.js"></script> 
<!-- Resizable columns --> 
<script src="https://rawgit.com/alvaro-prieto/colResizable/master/colResizable-1.6.js"></script> 
 
 
<div class="container"> 
  <h2>Bordered Table</h2> 
  <p>The .table-bordered class adds borders to a table:</p> 
  <table class="table table-bordered" id="flex"> 
    <thead> 
      <tr> 
        <th>Firstname</th> 
        <th>Lastname</th> 
        <th>Email</th> 
      </tr> 
    </thead> 
    <tbody> 
      <tr> 
        <td>John</td> 
        <td>Doe</td> 
        <td>john@example.com</td> 
      </tr> 
      <tr> 
        <td>Mary</td> 
        <td>Moe</td> 
        <td>mary@example.com</td> 
      </tr> 
      <tr> 
        <td>July</td> 
        <td>Dooley</td> 
        <td>july@example.com</td> 
      </tr> 
    </tbody> 
  </table> 
</div>