3/7 Short term memory - NaN


#1

Hi , I'm getting the following error message:
"Oops, try again. Calling cashRegister.add(3.2) set the cashRegister.total to NaN instead of 3.2"; What am I doing wrong?

var cashRegister = {
    total: 0,
//insert the add method here    
    add: function(itemCost){
        this.total+=this.itemCost;
    },
    
    scan: function (item) {
        switch (item) { 
        case "eggs": 
            this.add(0.98); 
            break;
        
        case "milk": 
            this.add(1.23); 
            break;
        
        //Add other 2 items here
        case "magazine":
            this.add(4.99);
            break;
        
        case "chocolate":
            this.add(0.45);
            break;
        }
    return true;   
    }
};

//Scan 2 eggs and 3 magazines
cashRegister.scan("eggs");
cashRegister.scan("eggs");
cashRegister.scan("magazine");
cashRegister.scan("magazine");
cashRegister.scan("magazine");
//Show the total bill
console.log('Your bill is '+ cashRegister.total);


#2

should read,

    this.total += itemCost;

itemCost is a locally defined variable, not a property of the cashRegister object.


#3

thank you, thank you, thank you. I was going crazy!