StaleWhileRevalidate.js 5.05 KB
/*
  Copyright 2018 Google LLC

  Use of this source code is governed by an MIT-style
  license that can be found in the LICENSE file or at
  https://opensource.org/licenses/MIT.
*/
import { assert } from 'workbox-core/_private/assert.js';
import { logger } from 'workbox-core/_private/logger.js';
import { WorkboxError } from 'workbox-core/_private/WorkboxError.js';
import { cacheOkAndOpaquePlugin } from './plugins/cacheOkAndOpaquePlugin.js';
import { Strategy } from './Strategy.js';
import { messages } from './utils/messages.js';
import './_version.js';
/**
 * An implementation of a
 * [stale-while-revalidate](https://developer.chrome.com/docs/workbox/caching-strategies-overview/#stale-while-revalidate)
 * request strategy.
 *
 * Resources are requested from both the cache and the network in parallel.
 * The strategy will respond with the cached version if available, otherwise
 * wait for the network response. The cache is updated with the network response
 * with each successful request.
 *
 * By default, this strategy will cache responses with a 200 status code as
 * well as [opaque responses](https://developer.chrome.com/docs/workbox/caching-resources-during-runtime/#opaque-responses).
 * Opaque responses are cross-origin requests where the response doesn't
 * support [CORS](https://enable-cors.org/).
 *
 * If the network request fails, and there is no cache match, this will throw
 * a `WorkboxError` exception.
 *
 * @extends workbox-strategies.Strategy
 * @memberof workbox-strategies
 */
class StaleWhileRevalidate extends Strategy {
    /**
     * @param {Object} [options]
     * @param {string} [options.cacheName] Cache name to store and retrieve
     * requests. Defaults to cache names provided by
     * {@link workbox-core.cacheNames}.
     * @param {Array<Object>} [options.plugins] [Plugins]{@link https://developers.google.com/web/tools/workbox/guides/using-plugins}
     * to use in conjunction with this caching strategy.
     * @param {Object} [options.fetchOptions] Values passed along to the
     * [`init`](https://developer.mozilla.org/en-US/docs/Web/API/WindowOrWorkerGlobalScope/fetch#Parameters)
     * of [non-navigation](https://github.com/GoogleChrome/workbox/issues/1796)
     * `fetch()` requests made by this strategy.
     * @param {Object} [options.matchOptions] [`CacheQueryOptions`](https://w3c.github.io/ServiceWorker/#dictdef-cachequeryoptions)
     */
    constructor(options = {}) {
        super(options);
        // If this instance contains no plugins with a 'cacheWillUpdate' callback,
        // prepend the `cacheOkAndOpaquePlugin` plugin to the plugins list.
        if (!this.plugins.some((p) => 'cacheWillUpdate' in p)) {
            this.plugins.unshift(cacheOkAndOpaquePlugin);
        }
    }
    /**
     * @private
     * @param {Request|string} request A request to run this strategy for.
     * @param {workbox-strategies.StrategyHandler} handler The event that
     *     triggered the request.
     * @return {Promise<Response>}
     */
    async _handle(request, handler) {
        const logs = [];
        if (process.env.NODE_ENV !== 'production') {
            assert.isInstance(request, Request, {
                moduleName: 'workbox-strategies',
                className: this.constructor.name,
                funcName: 'handle',
                paramName: 'request',
            });
        }
        const fetchAndCachePromise = handler.fetchAndCachePut(request).catch(() => {
            // Swallow this error because a 'no-response' error will be thrown in
            // main handler return flow. This will be in the `waitUntil()` flow.
        });
        void handler.waitUntil(fetchAndCachePromise);
        let response = await handler.cacheMatch(request);
        let error;
        if (response) {
            if (process.env.NODE_ENV !== 'production') {
                logs.push(`Found a cached response in the '${this.cacheName}'` +
                    ` cache. Will update with the network response in the background.`);
            }
        }
        else {
            if (process.env.NODE_ENV !== 'production') {
                logs.push(`No response found in the '${this.cacheName}' cache. ` +
                    `Will wait for the network response.`);
            }
            try {
                // NOTE(philipwalton): Really annoying that we have to type cast here.
                // https://github.com/microsoft/TypeScript/issues/20006
                response = (await fetchAndCachePromise);
            }
            catch (err) {
                if (err instanceof Error) {
                    error = err;
                }
            }
        }
        if (process.env.NODE_ENV !== 'production') {
            logger.groupCollapsed(messages.strategyStart(this.constructor.name, request));
            for (const log of logs) {
                logger.log(log);
            }
            messages.printFinalResponse(response);
            logger.groupEnd();
        }
        if (!response) {
            throw new WorkboxError('no-response', { url: request.url, error });
        }
        return response;
    }
}
export { StaleWhileRevalidate };