I am wondering if there's something I misunderstood here. The code is:

function countdown(n){
  if(n < 1) return [];
  let result = countdown(n - 1);
  result.unshift(n);
  return result;
}

I'm wondering why it can't be written like this:

function countdown(n){
  if(n < 1) return [];
  return countdown(n - 1).unshift(n);
}

This returns an error:

TypeError: countdown(...).unshift is not a function

Aren't both of them the same thing?