So I decided 5/7


#1

var lastTransactionAmount;
var cashRegister = {
total:0,

//Dont forget to add your property
add: function(itemCost) {
    this.total +=  itemCost;
    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

@06ny,
2 things to make in perfect.

-1 initialize your lastTransactionAmount -property like you did with your total property
-2 expand your voidLastTransaction-Method with 1 codeline
this.lastTransactionAmount = 0; to prevent this method to be used more then once.!!!


#3

Thank you. I already saw in problem 7 how the code should look like. Duly noted.