Bleep Bleep Why it that?


#1

I have two sets of code.
1. The first one I think is correct cannot pass the exercise.
2. The second one I think is wrong can pass the exercise.

Can anyone explain it to me ?

The first one :
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("magazine",3);

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

The second one:

var cashRegister = {
total: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);


#2

Void the last transaction and then add 3 instead

Last transaction:

cashRegister.scan('chocolate',4);

What you did in first case:

cashRegister.scan("magazine",3);

Long story short, you added wrong items in first code. :slight_smile: I wasn't testing anything else since your code gives some result, but this is your first error.


#3

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