<script type="text/javascript">
function logout()
{
  console.log('ajax');
  $.ajax({
    type: 'POST',
    url: '/logout',
    success: function (data) {
      location.reload();
    }
  });
}

<nav class="navbar navbar-inverse navbar-fixed-top">
<div class="container">
  <div class="collapse navbar-collapse" id="myNavbar">
    <ul class="nav navbar-nav navbar-right">
      <li style="margin-right: 10px">
        <button class="btn btn-default navbar-btn">
          <span class="glyphicon glyphicon-user"></span> Hello
          <%=sess_data.user %>
        </button>
      </li>
      <li>
        <form style="padding: 0px;margin: 0px">
          <button class="btn btn-primary navbar-btn" type="button" onclick=logout() id="logout">
            <span class="glyphicon glyphicon-user"></span> Log Out</button>
        </form>
      </li>
    </ul>
  </div>
</div>