const checkAvailability = useCallback(
    productId => {
      client.product.fetch(productId).then(fetchedProduct => {
        // this checks the currently selected variant for availability
        const result = fetchedProduct.variants.filter(
          variant => variant.id === productVariant.shopifyId
        )
        if (result.length > 0) {
          setAvailable(result[0].available)
        }
      })
    },
    [client.product, productVariant.shopifyId, variants]
  )

  useEffect(() => {
    checkAvailability(product.shopifyId)
  }, [productVariant, checkAvailability, product.shopifyId])