<article>I'm an article!</article>
<container>I'm a container!</container>
<figure><img data-description="Baby" id="baby" src="https://upload.wikimedia.org/wikipedia/en/9/9d/Maggie_Simpson.png" alt="Maggie Simpson">
<figcaption><p><mark>Maggie Simpson</mark> <small>(Wikipedia)</small></p>
</figcaption>
</figure>
<script> alert(document.getElementById("baby").getAttribute("data-description"));
</script>