@juanignaciomalerb4 Incorrect. If the array is empty, then 0 / 0 is done, which results in NaN (which is the expected result).

ooooh it makes sense now

I think because in the sum prototype he gives an initial value of 0 in the reduce function. So if an empty array is passed that will be the default value

I think they're equal. It's just the arrow one is shorter

what about empty array? does average() method still work?

some faith returned after this kata thx buddy <3

Is there any particular reason to use strict (in)equality here?

Where is division by 0 Test ?)

you'll still have an anonymous functon anyways (return function() {}).

Not the always, but only a one time during the initial initialization (self-invoking function). This migh explain something re initial initialization https://en.wikipedia.org/wiki/Memoization

When you pass a function from the outside as a parameter a code evaluation interpretator won't need to reinitialize the function every time when sun/whatever dependent function execution happens.

So when you for example do reduce in this way

function someFunc()
  return this.reduce(function(a, b) { return a + b; }, 0);
}

then reducing function initialization happens every time when you call the someFunc, in my opinion it's not the most optimal way, but I believe nowadays JS interpretators are able to omtimize such cases automatically.

I'm asking because I don't know (not to say you're wrong). Is using closure here really a better way? What benefit does this give? It seems like you'll still have an anonymous functon anyways (return function() {}).

I think it might be better using === or !==.

Nice touch reusing sum in average.

I was expecting to find an answer like this after I submitted my 50 line solution. Excellent, thanks a lot!