5/7 - Returning Your bill is NaN


#1

Hi there can someone take a look at my code below and let me know where I am going wrong. It keep saying "Oops, try again. False" and "Your bill is NaN" in the console.

var cashRegister = {
total:0,
//Dont forget to add your property
add: function(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(){
        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);


#2

In your cashRegister object
you have to initialize =lastTransactionAmount= as you did with =total=
and
in your add property you should assign / reassign =lastTransactionAmount= with itemCost


#3

var cashRegister = {
total:0,
lastTransactionAmount:0,
//Dont forget to add your property
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);


#4

Your code is Ok...
Maybe...
++++ reset of session *****************
As you are manipulating with objects
under certain circumstances you can shoot your Browser in an
inconsistent state.

Therefor it is of an advantage to know that you have 2 reset facilities:

One is the use of the F5-key which does a refresh Browser

and

Two, select&copy your code
Then use the Reset Code button of the course-window,
then paste your code back in.

Addendum
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