Designing a vending machine

vendingMachine.js

/*
##########
# PROMPT #
##########

- This vending machine must take user inputs (i.e. A1, A2, B1..etc) and dispenses an item after users input money. 
- There are only 9 inputs. 
- Assume that there are different kinds of items in the vending machine (Sprite, cheetos, etc).
- The vending machine must store instances of items to be dispensed, the item can't be created at the moment someone requests it.

###############
# ASSUMPTIONS #
###############

- has a glass front - no need to persist quantities or types of the items
- will still process a customer's purchase even if there are no more items in the vending machine
- would usually persist information mechanically
- persisting data (ex: amount a customer paid, vendingSelection prices) would normally be done
  mechanically but I'll mock data with objects where applicable


########
# TODO #
########
make change?  handle a no-change scenario?
*/


// - this would normally be done mechanically!  But for the sake of this
// exercise let's go ahead and process their payment anyway
var vendingSelections = {
  A1: {
    // price values in cents
    price: 150
  },
  A2: {
    price: 100
  },
  A3: {
    price: 100
  },
  B1: {
    price: 150
  },
  B2: {
    price: 100
  },
  B3: {
    price: 100
  },
  C1: {
    price: 150
  },
  C2: {
    price: 100
  },
  C3: {
    price: 100
  }
}

var processPayment = function(selection, payment){
  // no need to test for valid selections since they are predetermined by the 
  // buttons the user can push
  var balance = vendingSelections[selection][price] - payment
  if(!balance){
    dispenceItem(selection);
  }

  // TODO: make change
}

// this function connects to the physical machine and sends a signal to 
// mechanically dispence an item.  
var dispenseItem = function(selection){
  return {
    selection: selection
  }
}