CODEWITHSUNDEEP
javascript
Vito Martiradonna
Vito Martiradonna

Reputation: 63

TypeError: Cannot read properties of undefined while using getter js

I built two classes, a product with name and price and a shopping cart for an array of products; for the ShoppingCart get totPrice method I'm using the reduce() function on the array cart of the constructor, but I'm always getting the error above and I don't get why.

class Product {
    constructor(name,price) {
        this.name = name;
        this.price = price;
    }
    toString() {
        console.log(this.name + ' - ' + this.price);
    }
}

class ShoppingCart {
    constructor(cart) {
        this.cart = cart;
    }
    get totPrice() {
        return this.cart.reduce((el1,el2) => {el1.price + el2.price});
    }
    addProd = function(prod) {
        this.cart.push(prod);
        this.cart.totPrice += prod.price;
        if(this.cart.length >= 5){
            this.totPrice = this.totPrice * 0.9;
        }
        if(this.cart.filter(tmp => tmp.name === prod.name).length % 4 === 0){
            this.totPrice -= prod.price;
        }
    }
    removeProd = function(prod) {
        let i = this.cart.findIndex(el => {prod.name === el.name});
        this.cart.splice(i,1);
        console.log(`The product ${prod.name} has been removed from your shopping cart`);
    }
} 

let prod1 = new Product('Apple',15);

let prod2 = new Product('Banana',20);

let prod3 = new Product('Melon',25);

let shopCart = new ShoppingCart([prod1,prod2,prod3]);

console.log(shopCart.totPrice);

Upvotes: 0

Views: 178

Answers (1)

fludas
fludas

Reputation: 58

There is already an answer for this one explained here.

After the first iteration your're returning a number and then trying to get property sum.price of it to add it to the next object which is undefined. Also you need a initial value for the sum.

get totPrice() {
    return this.cart.reduce((acc,el) => acc + el.price,0);
}

Upvotes: 1

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