woocommerce/plugins/woocommerce-blocks/assets/js/base/utils/derive-selected-shipping-rates.js

/**
 * External dependencies
 */
import { fromEntriesPolyfill } from '@woocommerce/base-utils';

/**
 * Get an array of selected shipping rates keyed by Package ID.
 *
 * @param {Array} shippingRates Array of shipping rates.
 * @return {Object} Object containing the package IDs and selected rates in the format: { [packageId:string]: rateId:string }
 */
export const deriveSelectedShippingRates = ( shippingRates ) =>
	fromEntriesPolyfill(
		shippingRates.map(
			( { package_id: packageId, shipping_rates: packageRates } ) => [
				packageId,
				packageRates.find( ( rate ) => rate.selected )?.rate_id,
			]
		)
	);