Yeah, that's a strange piece of code, particularly since it introduces mutation (object[axis] = ...) and additional processing (reduce loop and inner function construction) that the naive example doesn't. It is slightly more generalizable to additional dimensions, but that seems awfully YAGNI to me. I suppose it prevents repetition of the Math.abs call and addition, but again that seems like massive overkill. I'd write it as follows, similar to yours:
TBH, this thread is pretty nitpicky, but I do agree with your assessment.
Yes and no.
On the one hand, the much more interesting parts here are the new APIs they've been using (and also IMHO the intelligent way they're handling compatibility and polyfills). All credit to the Stripe team both for making these tools work and for sharing what they've learned in the process for the benefit of others.
On the other hand, I think there is a real cultural problem in the JS community where newer is equated with better, and those defending that position will not infrequently appeal to authority by saying that Facebook or Stripe or Google or whoever does it so it must be a best practice. Grandpa here is getting awfully bored of young whippersnappers telling him code using new ES6 tricks is better (or, just as bad, that there's something wrong with clear, working code that does things in some older way). A gentle challenge to that assumption in a discussion about how these high profile organisations are using the new technologies doesn't seem either impolite or unjustified.
