Bleep Bleep


#1

I am getting a message saying: "Your bill is NaN"

Please Help.

var cashRegister = {
total:0,
//Dont forget to add your property
add: function(itemCost) {
this.total += itemCost;
this.lastTransactionAmout = 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(itemCost){
this.total -= this.voidLastTransaction;
},

};

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

I don't know if I'm right, but in:
//Add the voidLastTransaction Method here
voidLastTransaction: function(itemCost){
this.total -= this.voidLastTransaction;
},

try:
this.total -= this.lastTransactionAmout;


#3

You made two mistakes, actually. The one pointed out above by arcpro40227 and the fact that you didn't create the "lastTransactionAmount" property. Your code should look like this:

var cashRegister = {
total:0,
//Dont forget to add your property
lastTrasanction: 0,
add: function(itemCost) {
this.total += itemCost;
this.lastTransactionAmount = 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() {
this.total -= this.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);

I was also lost and your code gave me some perspective. Thank you. :smile: