Drop old Nodejs version support?

[hasezoey]

Do you want to request a feature or report a bug?
discussion

What is the current behavior?
Currently the code seems to be made for newer version of nodejs, while a effort was made to be nodejs 4.x compatible, but did not reach everywhere (like stringToParts.js is still let/const), so maybe consider dropping old version of nodejs (either by matching what mongoose requires or something like nodejs 8)

PS: it also seems old version are not even tested anymore (lowest version i see is 12)

[vkarpov15]

If memory serves, let and const work fine in Node 4 as long as you use strict mode. So that's not a problem.

But you're right that we should drop support for older versions of Node. No need to support anything below 12 these days. I'd like to do that before we ship a 1.0.0 release.