Add optional reverse argument to sortBy

[ludofischer]

I have often wished to be able to reuse the same iterator, but reverse the order of the sort, when implementing filter-type controls.

This functionality has been already proposed (#910) but with a different API. I hope this one feels more idiomatic.

[sindresorhus]

This is where I would have used a ternary: return reverse ? -1 : 1;

[ludofischer]

I have updated the pull request to use a ternary, which does better fit stylistically with the rest of the codebase.

[braddunbar]

Hi @ludovicofischer! Thanks for your patch. I don't think we want to go this direction with _.sortBy though. For one thing, it's a breaking change that would make all existing calls to _.sortBy which contain a context argument sort in reverse. Also, it's generally best to avoid boolean arguments like this, especially when the fix is so straightforward (define a separate comparator).

[ludofischer]

Yeah, it’s true no underscore method takes that kind of option modifying its behaviour.