Demonstration: http://www.verticalsysadmin.com/sha1clock/
Source code: https://gitlab.com/atsaloli/sha1-clock/tree/master
It was a fun little project for me as I'm a sysadmin and haven't done much with JavaScript.
I quickly found a SHA1 implementation through Google and then after realizing there really is no sleep() in JavaScript and to use setInterval instead, I was pretty much set. :-)
There is no practical value, it's just for amusement and for me to learn just enough JavaScript to make it work. :)