forEach on a 'new Array' isn't doing what I expect

Question

I\'m just learning how to use JS higher-order functions (map, forEach, reduce, etc), and have stumbled into confusion. I\'m trying to write a simple \'range\' function, but

Answer 1

The problem is that map doesn't iterate undefined entries (*).

I suggest using a for loop instead:

var rangeArr = new Array((num2 + 1) - num1);
for(var i=0; i<=num2-num1; ++i)
    rangeArr[i] = num1 + i;
return rangeArr;

(*) With undefined entries I mean rangeArr.hasOwnProperty(i) === false, not to be confused with rangeArr[i] === void 0.