[iso8859-1]

Typing fixes this, and anonymous records make it even better.

JavaScript lacks typing, and then they decided on a weird signature for the callback...

[simon04]

Unfortunately typing doesn't fix this. The 2nd callback function argument of Array.map is (index:number), and the 2nd argument of Number.parseInt is (radix:number).

It's a very nasty issue to debug.

[iso8859-1]

If there were typing, there would be no reason to not use newtypes[0] for radix and index. These values should only be explicitly unwrapped to plain numbers.

It would look like this

    newtype Radix = Radix { radixToWord :: Word }
    newtype Index = Index { indexToWord :: Word }

[0]: https://wiki.haskell.org/Newtype