age_restiction.twig

<!-- Modal -->
<div id="age-restriction-modal" class="modal fade" role="dialog">
  <div class="modal-dialog">
    <!-- Modal content-->
    <div class="modal-content">
      <div class="modal-header">
        <h4 class="modal-title">{{modal_title}}</h4>
      </div>
      <div class="modal-body">
        <p>{{message}}</p>
      </div>
      <div class="modal-footer">
        <button id="age-positive" type="button" class="btn btn-default" data-dismiss="modal">{{modal_agree}}</button>
        <button id="age-negative"  type="button" class="btn btn-default" data-dismiss="modal">{{modal_disagree}}</button>
      </div>
    </div>
  </div>
</div>

<script type="text/javascript">
    var AGE_RESTRICTION_SESSION_KEY = '{{session_redirect}}';

    window.addEventListener('load', function(){
        $(document.getElementById('age-restriction-modal')).modal({backdrop: "static"});


        document.getElementById('age-negative').addEventListener('click', function(){
            window.location = "{{redirect_url}}";
        });

        document.getElementById('age-positive').addEventListener('click', function(){
            $.post(AGE_RESTRICTION_SESSION_KEY, { age: {{age}} }, function(response){
                if (JSON.parse(response).success != 1) {
                  console.log('Session Error. Check your cookie!');
                }
            });
        });
    });
</script>