voidLastTransaction


#1

Can anyone figure out what's wrong with this?

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

Just going down through the code,

    add: function(itemCost, lastTransactionAmount) {

lastTransactionAmount is a property in object context so is not needed as a parameter. The method can see and access that property as,

    this.lastTransactionAmount

Your code should read,

    add: function (itemCost) {