undefined

points

[-]

OK, or maybe...

  total = calculateOrderTotal(user.order);
  total = total * user.discount;

[-]

Or:

  total = calculateOrderTotal(user.order);
  total *= user.discount;

or:

  return 
         calculateOrderTotal(user.order)
       * user.discount;

[-]

Didn't you just shift the branch to the calculateDiscount() function?

[-]

Not necessarily.

   return 1 - user.isPremiumMember * 0.1;

would also cut it.