This is fantastic, however it doesn't really completely replace the reasons for using something like date-fns.

Stuff like a "time-range" (both a "computer" value, and a "humanized" one like "10 minutes ago"), and other nice to haves.

There's no reason this can't be a good base going forward though! And for what it does cover, I really like the API.

This looks like a step in the right direction. I can't seem to find a polyfill though -- do you have a link to that?