this-is-js.factory-function-cart-product.js

function createProduct({ name, price  }) {
    function getName() {
        return name
    }

    function getPrice() {
        return price
    }

    return {
        getName,
        getPrice
    }
}

function createCart() {
    const data = {
        items: []
    }

    function onItemAddedToCart() {
        console.log(`The cart has ${data.items.length} items`)
    }

    function addItem(item) {
        return new Promise((resolve) => {
            setTimeout(() => {
                data.items.push(item)
                resolve()
            }, 500)
        }).then(onItemAddedToCart)
    }

    function showCartInfo() {
        data
            .items
            .forEach(item => console.log(`${item.getName()}: R$ ${item.getPrice()}`))
    }

    return {
        addItem,
        showCartInfo
    }
}

const notebook = createProduct({
    name: 'Notebook',
    price: 1000
})

const smartphone = createProduct({
    name: 'Smartphone',
    price: 500
})

const myCart = createCart()

Promise.all([
    myCart.addItem(notebook),
    myCart.addItem(smartphone)
]).then(() => {
    myCart.showCartInfo()
})