Javascript immutable way of updating shopping cart

immutable_cart.js

/*
Javascript: Immutable way of changing quantity in a shopping cart
*/
let cart = [{
        id: 1,
        quantity: 3
    },
    {
        id: 2,
        quantity: 4
    },
    {
        id: 3,
        quantity: 10
    }
];

const itemID = 2; // item id that should be changed

let modifiedCart = cart.map((item) => {
    if (item.id === itemID) {
        return {
            ...item,
            quantity: 1
        }
    }
    return item;
});

modifiedCart.forEach(val => console.log(val));