Var not needed in 5. bleep bleep


#1


5. Bleep bleep

My code works well, but I do not understand however
1. why the code can define a new variable "lastTransaction" without defining it with "var" prefix.
2. why can I access this variable in "voidLasttransaction" function although it is not a global variable


Replace this line with your code. 
var cashRegister = {
    total:0,
    //Dont forget to add your property
    add: function(itemCost) {
        this.total +=  itemCost;
        lastTransaction = 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 -= lastTransaction;
    }
    
};

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

1: In "loose mode" (contrary to "strict mode"), the JS engine allows you to create variables without the keyword "var". However, these variables will be global.
2: "voidLasttransaction" is an attribute - similar to the attribute "total" - of the object "cashRegister" and thus can be accessed via the dot notation.

Hope it helps. :slight_smile:


#3

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