updateQuantity

Add or substract the quantity of an item in the cart.

If the items is not yet in the cart, it will be added.

Example

import { updateQuantity } from "fullcart"

updateQuantity("your-product-id", 1)
updateQuantity("your-product-id", 5)
updateQuantity("your-product-id", -1)
updateQuantity("your-product-id", -8)