timey.js is a small dependency-free command line module written in node.js to convert between milliseconds and human-readable time.
Grab the timey.js project and place it somewhere semi-permanent on your system, then, from the project folder, run:
$ npm install -g .
This will register timey as a CLI command.
Install timey.js globally, and run it as follows to convert from milliseconds:
$ timey 23660001
23660001ms in human time is 06:34:20.001
... and like this to convert from human-readable time to milliseconds:
$ timey 06:34:20.001
06:34:20.001 in milliseconds is 23660001
Timey will try to guess whether the input time is in human-readable or millisecond time.
The ~ operator is javascript bitwise operator that flips the bits of the number it operates on; in practice, a double-tilde has the effect of performing an integer division of a by b, and it does this slightly faster than Math.floor() does.
More importantly, it's super-inscrutable and difficult to parse when reading code.
timey.js includes some minimally-useful unit tests; to run them:
$ npm install
$ npm test
(timey.js isn't packaged with its dev dependencies by default, so npm install is necessary to grab them before running any tests.)
MIT, I guess?