Tab Timer
<title id=t></title>
<script>
st = Date.now()
setInterval(_ => {
s = Date.now() - st
t.innerHTML =
~~(s/6e4)+':'+(~~(s/1e3)%60)
}, 500)
</script>
I speed coded this recently to put a timer in a brower tab.
Have a look at it here in a new tab…
Obviously this is pretty odd – but it does work for my purposes 😉