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/*
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
* [network first](https://developer.chrome.com/docs/workbox/caching-strategies-overview/#network-first-falling-back-to-cache)
* request strategy.
*
* 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 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 NetworkFirst 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)
* @param {number} [options.networkTimeoutSeconds] If set, any network requests
* that fail to respond within the timeout will fallback to the cache.
*
* This option can be used to combat
* "[lie-fi]{@link https://developers.google.com/web/fundamentals/performance/poor-connectivity/#lie-fi}"
* scenarios.
*/
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);
}
this._networkTimeoutSeconds = options.networkTimeoutSeconds || 0;
if (process.env.NODE_ENV !== 'production') {
if (this._networkTimeoutSeconds) {
assert.isType(this._networkTimeoutSeconds, 'number', {
moduleName: 'workbox-strategies',
className: this.constructor.name,
funcName: 'constructor',
paramName: 'networkTimeoutSeconds',
});
}
}
}
/**
* @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: 'makeRequest',
});
}
const promises = [];
let timeoutId;
if (this._networkTimeoutSeconds) {
const { id, promise } = this._getTimeoutPromise({ request, logs, handler });
timeoutId = id;
promises.push(promise);
}
const networkPromise = this._getNetworkPromise({
timeoutId,
request,
logs,
handler,
});
promises.push(networkPromise);
const response = await handler.waitUntil((async () => {
// Promise.race() will resolve as soon as the first promise resolves.
return ((await handler.waitUntil(Promise.race(promises))) ||
// If Promise.race() resolved with null, it might be due to a network
// timeout + a cache miss. If that were to happen, we'd rather wait until
// the networkPromise resolves instead of returning null.
// Note that it's fine to await an already-resolved promise, so we don't
// have to check to see if it's still "in flight".
(await networkPromise));
})());
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 });
}
return response;
}
/**
* @param {Object} options
* @param {Request} options.request
* @param {Array} options.logs A reference to the logs array
* @param {Event} options.event
* @return {Promise<Response>}
*
* @private
*/
_getTimeoutPromise({ request, logs, handler, }) {
let timeoutId;
const timeoutPromise = new Promise((resolve) => {
const onNetworkTimeout = async () => {
if (process.env.NODE_ENV !== 'production') {
logs.push(`Timing out the network response at ` +
`${this._networkTimeoutSeconds} seconds.`);
}
resolve(await handler.cacheMatch(request));
};
timeoutId = setTimeout(onNetworkTimeout, this._networkTimeoutSeconds * 1000);
});
return {
promise: timeoutPromise,
id: timeoutId,
};
}
/**
* @param {Object} options
* @param {number|undefined} options.timeoutId
* @param {Request} options.request
* @param {Array} options.logs A reference to the logs Array.
* @param {Event} options.event
* @return {Promise<Response>}
*
* @private
*/
async _getNetworkPromise({ timeoutId, request, logs, handler, }) {
let error;
let response;
try {
response = await handler.fetchAndCachePut(request);
}
catch (fetchError) {
if (fetchError instanceof Error) {
error = fetchError;
}
}
if (timeoutId) {
clearTimeout(timeoutId);
}
if (process.env.NODE_ENV !== 'production') {
if (response) {
logs.push(`Got response from network.`);
}
else {
logs.push(`Unable to get a response from the network. Will respond ` +
`with a cached response.`);
}
}
if (error || !response) {
response = await handler.cacheMatch(request);
if (process.env.NODE_ENV !== 'production') {
if (response) {
logs.push(`Found a cached response in the '${this.cacheName}'` + ` cache.`);
}
else {
logs.push(`No response found in the '${this.cacheName}' cache.`);
}
}
}
return response;
}
}
export { NetworkFirst };