Function onAdd

context/StateContext.js:16–38

(product, quantity)

  let index;

  const onAdd = (product, quantity) => {
    const checkProductInCart = cartItems.find((item) => item._id === product._id);
    
    setTotalPrice((prevTotalPrice) => prevTotalPrice + product.price * quantity);
    setTotalQty((prevTotalQty) => prevTotalQty + quantity);
    
    if(checkProductInCart) {
      const updatedCartItems = cartItems.map((cartProduct) => {
        if(cartProduct._id === product._id) return {
          ...cartProduct,
          quantity: cartProduct.quantity + quantity
        }
      })

      setCartItems(updatedCartItems);
    } else {
      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);