Bleep Bleep why


#1


Building a cash register: Bleep Bleep


My code works fine (after LOTS of trial and error). I do not understand why to call voidLastTransaction I need to write cashRegister.voidLastTransaction(); instead of just voidLastTransaction();

Thanks!


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() {
        cashRegister.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();
//why not just voidLastTransaction();
cashRegister.scan("chocolate", 3);


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


#2

You need to call voidLastTransaction() on the specific cashRegister object.


#3

Thanks. The method is within the cashRegister object. Do all methods need to specify the object? And if I had another function is it safe to assume I could not call the voidLastTransaction method (or scan/add either) as it would be in a separate function?


#4

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