js alert显示图片

<img src="path_to_your_image.jpg" alt="Description of the image">

var img = document.createElement('img');
img.src = 'path_to_your_image.jpg';
img.alt = 'Description of the image';
document.body.appendChild(img);

<!-- Button trigger modal -->
<button type="button" class="btn btn-primary" data-toggle="modal" data-target="#imageModal">
  Launch demo modal
</button>

<!-- Modal -->
<div class="modal fade" id="imageModal" tabindex="-1" role="dialog" aria-labelledby="imageModalLabel" aria-hidden="true">
  <div class="modal-dialog" role="document">
    <div class="modal-content">
      <div class="modal-body">
        <img src="path_to_your_image.jpg" class="img-fluid">
      </div>
    </div>
  </div>
</div>