Extremely lightweight "lightbox". Zero-dependencies. Only 1.4 KB. And that's without minification and gzip.
<script src="https://cdn.jsdelivr.net/gh/jitbit/nanobox/nanobox.js"></script>
<a class="something" href="https://i.imgur.com/F36gf2O.jpg">click me</a>
<script>
Nanobox.attach("a.something");
</script>If the link points to an image - clicking the link will show an image modal.
If not - if will show an iframe pointing to the link (so you can use it with Yoututbe videos for example)