[解決済み] data-id属性を取得するにはどうすればよいですか？

$("#list li").on('click', function() {
  //  ret = DetailsView.GetProject($(this).attr("#data-id"), OnComplete, OnTimeOut, OnError);
  alert($(this).attr("#data-id"));
});

<script src="https://code.jquery.com/jquery-3.3.1.slim.min.js"></script>

<ul id="list" class="grid">
  <li data-id="id-40" class="win">
    <a id="ctl00_cphBody_ListView1_ctrl0_SelectButton" class="project" href="#">
      <img src="themes/clean/images/win.jpg" class="project-image" alt="get data-id" />
    </a>
  </li>
</ul>