Get stuck!


#1


https://www.codecademy.com/courses/close-the-super-makert/0/5?curriculum_id=506324b3a7dffd00020bf661#


Oops, try again. false
Your bill is NaN


var cashRegister = {
    total:0,
    //Dont forget to add your property
    add: function(itemCost) {
        this.total +=  itemCost;
        lastTransactionAmount = this.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 = 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('eggs',3);
cashRegister.scan('milk',3);
cashRegister.scan('magazine',3);
cashRegister.scan('chocolate',3);

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


#2

@neagumihai54321gmail Here are some problems:

delete this:

also delete:

(Sorry about having this(<) but I added so you can see the minus sign)

and change this:

to this:

this.total -= this.lastTransaction

also change this:

to this:

this.lastTransaction = itemCost;

Hope this helps

Steven


#3

@steven.copeland
@neagumihai54321gmail

 +- cashRegister-object -----------------+
 |                                       |
 | all properties are referred to using  |
 |           this    keyword             |
 |                                       |
 |  this.total                           |
 |         this.lastTransactionAmount    |
 |                                       |
 +---------------------------------------+

===================================================

the this-keyword explained
using Dog class-constructor and snoopy Instance of Dog
http://www.codecademy.com/forum_questions/54809212631fe9483b007e43

-------------------------------------------------

google search
+++ this explained
javascript this explained site:stackoverflow.com
http://stackoverflow.com/questions/3127429/how-does-the-this-keyword-work
https://www.codecademy.com/forum_questions/55f03d4b93767651db0005b3

-------------------------------------------------

Reference::

google search
== the Book ==
javascript this site:developer.mozilla.org
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/this
Have a read through
http://stackoverflow.com/questions/4354418/var-vs-this-vs-constructor-parameter-variables
and
http://javascriptweblog.wordpress.com/2010/08/30/understanding-javascripts-this/


#4

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