5/7 So Confused


#1

I know I messed up somewhere, but idk where. It keeps printing out "Your bill is NaN".

var cashRegister = {
total:0,
//Dont forget to add your property
lastTransactionAmount:0,
add: function(itemCost) {
lastTransactionAmount = itemCost;
this.total += itemCost;
},
scan: function(item,quantity) {
switch (item) {
case "eggs": this.add(0.98 * quantity); break;
case "milk": this.add(1.23 * quantity); break;
case "magazine": this.add(4.99 * quantity); break;
case "chocolate": this.add(0.45 * quantity); break;
}
return true;
},
//Add the voidLastTransaction Method here
voidLastTransaction: function(lastTransactionAmount) {
this.total -= lastTransactionAmount;
}
};

cashRegister.scan('eggs',1);
cashRegister.scan('milk',1);
cashRegister.scan('magazine',1);
cashRegister.scan('chocolate',4);

//Void the last transaction and then add 3 instead
cashRegister.voidLastTransaction();
cashRegister.scan('chocolate',3);

//Show the total bill
console.log('Your bill is '+cashRegister.total);


#2
voidLastTransaction: function(lastTransactionAmount) {
    this.total -= lastTransactionAmount;
}

This method does not take any parameters, and needs to refer to the member variable...

    voidLastTransaction: function() {
        this.total -= this.lastTransactionAmount;
    }