16 Building a Cash Register


var cashRegister = {
//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() {
cashRegister.total -= lastTransactionAmount;
//takes away the value of the last transaction form the current list of transactions



//Void the last transaction and then add 3 instead
//why not just voidLastTransaction();
cashRegister.scan("chocolate", 3);

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

okay so the code above runs just perfectly, however I'm just not quite understanding why we can use "lastTransactionAmount" which has been created inside a different function from the one of which it is called in "voidLastTransaction"


voidLastTransaction method belongs to cashRegister object, that's why you cannot call it directly.

Regarding lastTransactionAmount - you actually forgot to declare this property. It belongs right after total.


do you mean declare it outside of the add function?


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