Modify Jekyll on Github Pages' image & alt-text behavior to work with figures and figcaptions

jekyll-images-figure.js

<script>
  /* Pulls images with alt text out of paragraphs, puts them into <figure> elements with <figcaption>s */
  var imgs = document.querySelectorAll('article p img');
  [].forEach.call(imgs, function(e){
    var d = document.createElement('figure');
    d.innerHTML = '<img src="' + e.src + '" alt="' + e.alt + '"><figcaption>' + e.alt + '</figcaption>';
    e.parentNode.insertBefore(d, e);
    e.parentNode.removeChild(e);
  });
</script>

e.parentNode.replaceChild(d, e); would cut a line out