cart-utils/index.js

Shopping cart utilities for cart total, subtotal, and shipping cost

const TAX_RATE = process.env.TAX_RATE || 0.06625
const SHIPPING_RATE = process.env.SHIPPING_RATE || 500
const FREE_SHIPPING_THRESHOLD = process.env.FREE_SHIPPING_THRESHOLD || 10000

const cartSubtotal = (cart) => {
  const subTotal = cart.reduce((counter, product) => {
    return counter + product.price_in_cent * product.qty
  }, 0)
  return subTotal
}

const cartTaxes = (cart) => {
  const subTotal = cartSubtotal(cart)
  return subTotal * TAX_RATE
}

const cartTotal = (cart) => {
  if (cart.length === 0) {
    return 0
  }
  const subTotal = cartSubtotal(cart)
  const shipping = shouldPayShipping(cart) ? SHIPPING_RATE : 0
  const total = subTotal + cartTaxes(cart) + shipping

  return Math.round(total)
}

const shouldPayShipping = (cart) => {
  const subTotal = cartSubtotal(cart)

  return subTotal < FREE_SHIPPING_THRESHOLD
}

module.exports = {
  cartSubtotal,
  cartTaxes,
  cartTotal,
  shouldPayShipping,
}