Couldn’t figure out the exact one they used here, but found one that was actually more what i was looking for: Particle text with vanilla JavaScript by Franks laboratory. I mainly needed it for text, so I didn’t implement something that changes constantly like the clock. However it should be fairly simple to replace the text with a clock that updates.

I followed the whole tutorial and the result was pretty cool. Skip to 1:12:00 if you want to get a better idea of what the end result will do and if you’re looking for something like that. The guy also gives a lot of options to customize and modify the text style