PrecacheStrategy.js
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/*
Copyright 2020 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 { copyResponse } from 'workbox-core/copyResponse.js';
import { cacheNames } from 'workbox-core/_private/cacheNames.js';
import { getFriendlyURL } from 'workbox-core/_private/getFriendlyURL.js';
import { logger } from 'workbox-core/_private/logger.js';
import { WorkboxError } from 'workbox-core/_private/WorkboxError.js';
import { Strategy } from 'workbox-strategies/Strategy.js';
import './_version.js';
/**
* A {@link workbox-strategies.Strategy} implementation
* specifically designed to work with
* {@link workbox-precaching.PrecacheController}
* to both cache and fetch precached assets.
*
* Note: an instance of this class is created automatically when creating a
* `PrecacheController`; it's generally not necessary to create this yourself.
*
* @extends workbox-strategies.Strategy
* @memberof workbox-precaching
*/
class PrecacheStrategy extends Strategy {
/**
*
* @param {Object} [options]
* @param {string} [options.cacheName] Cache name to store and retrieve
* requests. Defaults to the cache names provided by
* {@link workbox-core.cacheNames}.
* @param {Array<Object>} [options.plugins] {@link https://developers.google.com/web/tools/workbox/guides/using-plugins|Plugins}
* to use in conjunction with this caching strategy.
* @param {Object} [options.fetchOptions] Values passed along to the
* {@link https://developer.mozilla.org/en-US/docs/Web/API/WindowOrWorkerGlobalScope/fetch#Parameters|init}
* of all fetch() requests made by this strategy.
* @param {Object} [options.matchOptions] The
* {@link https://w3c.github.io/ServiceWorker/#dictdef-cachequeryoptions|CacheQueryOptions}
* for any `cache.match()` or `cache.put()` calls made by this strategy.
* @param {boolean} [options.fallbackToNetwork=true] Whether to attempt to
* get the response from the network if there's a precache miss.
*/
constructor(options = {}) {
options.cacheName = cacheNames.getPrecacheName(options.cacheName);
super(options);
this._fallbackToNetwork =
options.fallbackToNetwork === false ? false : true;
// Redirected responses cannot be used to satisfy a navigation request, so
// any redirected response must be "copied" rather than cloned, so the new
// response doesn't contain the `redirected` flag. See:
// https://bugs.chromium.org/p/chromium/issues/detail?id=669363&desc=2#c1
this.plugins.push(PrecacheStrategy.copyRedirectedCacheableResponsesPlugin);
}
/**
* @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 response = await handler.cacheMatch(request);
if (response) {
return response;
}
// If this is an `install` event for an entry that isn't already cached,
// then populate the cache.
if (handler.event && handler.event.type === 'install') {
return await this._handleInstall(request, handler);
}
// Getting here means something went wrong. An entry that should have been
// precached wasn't found in the cache.
return await this._handleFetch(request, handler);
}
async _handleFetch(request, handler) {
let response;
const params = (handler.params || {});
// Fall back to the network if we're configured to do so.
if (this._fallbackToNetwork) {
if (process.env.NODE_ENV !== 'production') {
logger.warn(`The precached response for ` +
`${getFriendlyURL(request.url)} in ${this.cacheName} was not ` +
`found. Falling back to the network.`);
}
const integrityInManifest = params.integrity;
const integrityInRequest = request.integrity;
const noIntegrityConflict = !integrityInRequest || integrityInRequest === integrityInManifest;
// Do not add integrity if the original request is no-cors
// See https://github.com/GoogleChrome/workbox/issues/3096
response = await handler.fetch(new Request(request, {
integrity: request.mode !== 'no-cors'
? integrityInRequest || integrityInManifest
: undefined,
}));
// It's only "safe" to repair the cache if we're using SRI to guarantee
// that the response matches the precache manifest's expectations,
// and there's either a) no integrity property in the incoming request
// or b) there is an integrity, and it matches the precache manifest.
// See https://github.com/GoogleChrome/workbox/issues/2858
// Also if the original request users no-cors we don't use integrity.
// See https://github.com/GoogleChrome/workbox/issues/3096
if (integrityInManifest &&
noIntegrityConflict &&
request.mode !== 'no-cors') {
this._useDefaultCacheabilityPluginIfNeeded();
const wasCached = await handler.cachePut(request, response.clone());
if (process.env.NODE_ENV !== 'production') {
if (wasCached) {
logger.log(`A response for ${getFriendlyURL(request.url)} ` +
`was used to "repair" the precache.`);
}
}
}
}
else {
// This shouldn't normally happen, but there are edge cases:
// https://github.com/GoogleChrome/workbox/issues/1441
throw new WorkboxError('missing-precache-entry', {
cacheName: this.cacheName,
url: request.url,
});
}
if (process.env.NODE_ENV !== 'production') {
const cacheKey = params.cacheKey || (await handler.getCacheKey(request, 'read'));
// Workbox is going to handle the route.
// print the routing details to the console.
logger.groupCollapsed(`Precaching is responding to: ` + getFriendlyURL(request.url));
logger.log(`Serving the precached url: ${getFriendlyURL(cacheKey instanceof Request ? cacheKey.url : cacheKey)}`);
logger.groupCollapsed(`View request details here.`);
logger.log(request);
logger.groupEnd();
logger.groupCollapsed(`View response details here.`);
logger.log(response);
logger.groupEnd();
logger.groupEnd();
}
return response;
}
async _handleInstall(request, handler) {
this._useDefaultCacheabilityPluginIfNeeded();
const response = await handler.fetch(request);
// Make sure we defer cachePut() until after we know the response
// should be cached; see https://github.com/GoogleChrome/workbox/issues/2737
const wasCached = await handler.cachePut(request, response.clone());
if (!wasCached) {
// Throwing here will lead to the `install` handler failing, which
// we want to do if *any* of the responses aren't safe to cache.
throw new WorkboxError('bad-precaching-response', {
url: request.url,
status: response.status,
});
}
return response;
}
/**
* This method is complex, as there a number of things to account for:
*
* The `plugins` array can be set at construction, and/or it might be added to
* to at any time before the strategy is used.
*
* At the time the strategy is used (i.e. during an `install` event), there
* needs to be at least one plugin that implements `cacheWillUpdate` in the
* array, other than `copyRedirectedCacheableResponsesPlugin`.
*
* - If this method is called and there are no suitable `cacheWillUpdate`
* plugins, we need to add `defaultPrecacheCacheabilityPlugin`.
*
* - If this method is called and there is exactly one `cacheWillUpdate`, then
* we don't have to do anything (this might be a previously added
* `defaultPrecacheCacheabilityPlugin`, or it might be a custom plugin).
*
* - If this method is called and there is more than one `cacheWillUpdate`,
* then we need to check if one is `defaultPrecacheCacheabilityPlugin`. If so,
* we need to remove it. (This situation is unlikely, but it could happen if
* the strategy is used multiple times, the first without a `cacheWillUpdate`,
* and then later on after manually adding a custom `cacheWillUpdate`.)
*
* See https://github.com/GoogleChrome/workbox/issues/2737 for more context.
*
* @private
*/
_useDefaultCacheabilityPluginIfNeeded() {
let defaultPluginIndex = null;
let cacheWillUpdatePluginCount = 0;
for (const [index, plugin] of this.plugins.entries()) {
// Ignore the copy redirected plugin when determining what to do.
if (plugin === PrecacheStrategy.copyRedirectedCacheableResponsesPlugin) {
continue;
}
// Save the default plugin's index, in case it needs to be removed.
if (plugin === PrecacheStrategy.defaultPrecacheCacheabilityPlugin) {
defaultPluginIndex = index;
}
if (plugin.cacheWillUpdate) {
cacheWillUpdatePluginCount++;
}
}
if (cacheWillUpdatePluginCount === 0) {
this.plugins.push(PrecacheStrategy.defaultPrecacheCacheabilityPlugin);
}
else if (cacheWillUpdatePluginCount > 1 && defaultPluginIndex !== null) {
// Only remove the default plugin; multiple custom plugins are allowed.
this.plugins.splice(defaultPluginIndex, 1);
}
// Nothing needs to be done if cacheWillUpdatePluginCount is 1
}
}
PrecacheStrategy.defaultPrecacheCacheabilityPlugin = {
async cacheWillUpdate({ response }) {
if (!response || response.status >= 400) {
return null;
}
return response;
},
};
PrecacheStrategy.copyRedirectedCacheableResponsesPlugin = {
async cacheWillUpdate({ response }) {
return response.redirected ? await copyResponse(response) : response;
},
};
export { PrecacheStrategy };