Yes, and I've not seen this before, the HTML uses an SVG with an emoji in it as the favicon:

    <link rel="icon" href="data:image/svg+xml,<svg xmlns=%22http://www.w3.org/2000/svg%22 viewBox=%220 0 100 100%22>
      <text y=%22.9em%22 font-size=%2290%22>
        :( HN has remove the emoji
      </text>
    </svg>">

Very neat. Might use that.

I'm just learning JS and P5.play - possibly a daft question why is using SVG useful over say just an emoji/text?

It's interesting (to me) in this specific example because it generates a favicon using SVG + emoji. I wasn't aware that could be done. Favicons can't be simple enoji/text, they have to be an image.

big thanks for the reply

the grid is made up of <p> fields, I thought you just could replace the sqiggly line (background) with an emoji/text using the right font etc instead of svg/emoji

No worries. And yes, but that's not what I'm taking about :) I was interested in the favicon, which is the icon shown in the (desktop) browser tab.

https://en.m.wikipedia.org/wiki/Favicon

That’s what I do on my site! It is (AFAIK) the only way to get platform-specific, dynamic emojis as the favicon.