woocommerce/plugins/woocommerce-blocks/assets/js/middleware/store-api-nonce.js

/**
 * External dependencies
 */
import apiFetch from '@wordpress/api-fetch';

// Stores the current nonce for the middleware.
let currentNonce = '';
let currentTimestamp = 0;

try {
	const storedNonceValue = window.localStorage.getItem( 'storeApiNonce' );
	const storedNonce = storedNonceValue ? JSON.parse( storedNonceValue ) : {};
	currentNonce = storedNonce?.nonce || '';
	currentTimestamp = storedNonce?.timestamp || 0;
} catch {
	// We can ignore an error from JSON parse.
}

/**
 * Returns whether or not this is a wc/store API request.
 *
 * @param {Object} options Fetch options.
 *
 * @return {boolean} Returns true if this is a store request.
 */
const isStoreApiRequest = ( options ) => {
	const url = options.url || options.path;
	if ( ! url || ! options.method || options.method === 'GET' ) {
		return false;
	}
	return /wc\/store\/v1\//.exec( url ) !== null;
};

/**
 * Set the current nonce from a header object.
 *
 * @param {Object} headers Headers object.
 */
const setNonce = ( headers ) => {
	const nonce =
		typeof headers?.get === 'function'
			? headers.get( 'Nonce' )
			: headers.Nonce;
	const timestamp =
		typeof headers?.get === 'function'
			? headers.get( 'Nonce-Timestamp' )
			: headers[ 'Nonce-Timestamp' ];

	if ( nonce ) {
		updateNonce( nonce, timestamp );
	}
};

/**
 * Updates the stored nonce within localStorage so it is persisted between page loads.
 *
 * @param {string} nonce     Incoming nonce string.
 * @param {number} timestamp Timestamp from server of nonce.
 */
const updateNonce = ( nonce, timestamp ) => {
	// If the "new" nonce matches the current nonce, we don't need to update.
	if ( nonce === currentNonce ) {
		return;
	}

	// Only update the nonce if newer. It might be coming from cache.
	if ( currentTimestamp && timestamp < currentTimestamp ) {
		return;
	}

	currentNonce = nonce;
	currentTimestamp = timestamp || Date.now() / 1000; // Convert ms to seconds to match php time()

	// Update the persisted values.
	window.localStorage.setItem(
		'storeApiNonce',
		JSON.stringify( {
			nonce: currentNonce,
			timestamp: currentTimestamp,
		} )
	);
};

const appendNonceHeader = ( request ) => {
	const headers = request.headers || {};
	request.headers = {
		...headers,
		Nonce: currentNonce,
	};
	return request;
};

/**
 * Nonce middleware which appends the current nonce to store API requests.
 *
 * @param {Object}   options Fetch options.
 * @param {Function} next    The next middleware or fetchHandler to call.
 * @return {*} The evaluated result of the remaining middleware chain.
 */
const storeNonceMiddleware = ( options, next ) => {
	if ( isStoreApiRequest( options ) ) {
		options = appendNonceHeader( options );

		// Add nonce to sub-requests
		if ( Array.isArray( options?.data?.requests ) ) {
			options.data.requests = options.data.requests.map(
				appendNonceHeader
			);
		}
	}
	return next( options, next );
};

apiFetch.use( storeNonceMiddleware );
apiFetch.setNonce = setNonce;

updateNonce(
	// @ts-ignore wcBlocksMiddlewareConfig is window global cache for the initial nonce initialized from hydration.
	wcBlocksMiddlewareConfig.storeApiNonce,
	// @ts-ignore wcBlocksMiddlewareConfig is window global cache for the initial nonce initialized from hydration.
	wcBlocksMiddlewareConfig.storeApiNonceTimestamp
);