Function onAdd

context/StateContext2.js:16–40

(product, quantity)

    let index;

    const onAdd = (product, quantity) => {
        // check if product already in the cart
        const checkProductInCart = cartItems.find((item) => item._id === product._id);
        
        setTotalPrice((prevTotalPrice) => prevTotalPrice + product.price * quantity);
        setTotalQty((prevTotalQty) => prevTotalQty + quantity);

        // if product already in cart, then increase the qty of product instead of add the same product in cart
        if(checkProductInCart) {
            // update the actual item in the cart
            const updatedCartItems = cartItems.map((cartProduct) => {
                if(cartProduct._id === product._id) return {
                    ...cartProduct,
                    quantity: cartProduct.quantity + quantity
                }
            })

            setCartItems(updatedCartItems);
        } else {
            // if when dont have the item in the cart
            product.quantity = quantity;
            setCartItems([...cartItems, {...product}]);
        }
        toast.success(`${qty} ${product.name} added to the cart`);
    }

    const onRemove = (product) => {
        foundProduct = cartItems.find((item) => item._id === product._id)