A use for the Array() constructor!

makeN.js

function makeN(n, obj) {
  // gotta use .apply(null) because Array(n) makes a new empty array of size n and map behaves starngely
  // Array.apply(null, Array(n)) creates an array of size n with undefined as the value of every item
  // we can then call map on it to get back an array with n `obj`s.
  return Array.apply(null, Array(n)).map(function() { return obj; });
}

http://cl.ly/image/0r3V1W2o0l0d

It is only called for elements of the array which actually exists, this gotcha exists for forEach as well.

Array(10).forEach(function(){ console.log('hi'); });

Silence...

Ah, that makes sense.

Also... Traceur/ES6 http://jsbin.com/vayayevo/1/edit