JS is a language where [1,2,11].sort() returns [1,11,2].
And if you use a variable instead of a bare array, half the functions are side-effectful, as determined by coin toss.
And if you try declaring that variable with new Array(3).map() then it will ignore all 3 indices, because undefined is real enough to be enumerated, but not real enough to be iterated, because, and I cannot overstress the importance of this principle in Javascript, go fuck yourself. Go fuck yourself is why.
Array(3) doesn't create [undefined, undefined, undefined, ]; it creates [/* hole */, /* hole */, /* hole */, ]. The holes don't set any property on the array whatsoever, so they are skipped when iterating. How this makes sense, I can't tell you.
the is_even package does not provide much worth indeed because it simply negates is_odd and thereby all its benefit.
It's dependency is_odd on the other hand provides at least some additional checks (it also checks if the value is a valid integer below the max int value)
And while I would indeed see uses for such methods (especially with the other checks, no simple oneliners) in some cases, especially in testing: This is stuff you write yourself, throw it in a e.g. NumberUtils class and everything is fine. You do never depend on an external library for that. The benefit (not spending a few seconds to write it) does not outweigh any of the drawbacks that come with external libraries.