A sample modifier to apply tax information to a set of room rates

applyTax.js

var Promise = require('bluebird');
module.exports = function create(taxService) {

    function addTaxInformation(id, roomRates) {
        return Promise.each(roomRates, function (roomRate) {
            return taxService.getTaxInformation(id, roomRate.total.price)
                .then(function (taxInformation) {
                    if (taxInformation) {
                        roomRate.total.priceBeforeTax = taxInformation.priceBeforeTax;
                        roomRate.taxes = taxInformation.taxBreakdown;
                    }
                });
        }).then(function () {
            return roomRates;
        });
    }

    return function modifyRoomRates(originalRoomRates, id) {
        return addTaxInformation(id, originalRoomRates);
    };
};