关闭bootstrap 4模式窗口防止模式窗口在关闭的窗口下滚动

<!-- HTML代码 -->
<button type="button" class="btn btn-primary" data-toggle="modal" data-target="#myModal">
  打开模态框
</button>

<div class="modal" id="myModal">
  <div class="modal-dialog">
    <div class="modal-content">
      <!-- 模态框内容 -->
      <div class="modal-header">
        <h5 class="modal-title">模态框标题</h5>
        <button type="button" class="close" data-dismiss="modal" aria-label="Close">
          <span aria-hidden="true">&times;</span>
        </button>
      </div>
      <div class="modal-body">
        <p>模态框内容</p>
      </div>
      <div class="modal-footer">
        <button type="button" class="btn btn-secondary" data-dismiss="modal">关闭</button>
        <button type="button" class="btn btn-primary">保存</button>
      </div>
    </div>
  </div>
</div>

<script>
  // JavaScript代码
  $('#myModal').on('hidden.bs.modal', function () {
    $('body').css('overflow', 'hidden');
  });
</script>