100 lines
3.6 KiB
JavaScript
100 lines
3.6 KiB
JavaScript
/*
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Copyright 2016 Google Inc. All Rights Reserved.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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import {WorkboxError} from 'workbox-core/_private/WorkboxError.mjs';
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import {responsesAreSame} from './utils/responsesAreSame.mjs';
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import {broadcastUpdate} from './broadcastUpdate.mjs';
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import './_version.mjs';
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/**
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* Uses the [Broadcast Channel API]{@link https://developers.google.com/web/updates/2016/09/broadcastchannel}
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* to notify interested parties when a cached response has been updated.
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*
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* For efficiency's sake, the underlying response bodies are not compared;
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* only specific response headers are checked.
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*
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* @memberof workbox.broadcastUpdate
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*/
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class BroadcastCacheUpdate {
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/**
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* Construct a BroadcastCacheUpdate instance with a specific `channelName` to
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* broadcast messages on
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*
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* @param {string} channelName The name that will be used when creating
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* the `BroadcastChannel`.
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* @param {Object} options
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* @param {Array<string>}
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* [options.headersToCheck=['content-length', 'etag', 'last-modified']] A
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* list of headers that will be used to determine whether the responses
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* differ.
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* @param {string} [options.source='workbox-broadcast-cache-update'] An
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* attribution value that indicates where the update originated.
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*/
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constructor(channelName, {headersToCheck, source} = {}) {
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if (process.env.NODE_ENV !== 'production') {
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if (typeof channelName !== 'string' || channelName.length === 0) {
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throw new WorkboxError('channel-name-required');
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}
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}
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this._channelName = channelName;
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this._headersToCheck = headersToCheck || [
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'content-length',
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'etag',
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'last-modified',
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];
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this._source = source || 'workbox-broadcast-cache-update';
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// TODO assert typeof headersToCheck instanceof Array
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}
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/**
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* @return {BroadcastChannel|undefined} The BroadcastChannel instance used for
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* broadcasting updates, or undefined if the browser doesn't support the
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* Broadcast Channel API.
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*
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* @private
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*/
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_getChannel() {
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if (('BroadcastChannel' in self) && !this._channel) {
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this._channel = new BroadcastChannel(this._channelName);
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}
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return this._channel;
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}
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/**
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* Compare two [Responses](https://developer.mozilla.org/en-US/docs/Web/API/Response)
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* and send a message via the
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* {@link https://developers.google.com/web/updates/2016/09/broadcastchannel|Broadcast Channel API}
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* if they differ.
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*
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* Neither of the Responses can be {@link http://stackoverflow.com/questions/39109789|opaque}.
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*
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* @param {Response} firstResponse First responses to compare.
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* @param {Response} secondResponse Second responses to compare.
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* @param {string} url The URL of the updated request.
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* @param {string} cacheName Name of the cache the responses belong to.
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* This is included in the message posted on the broadcast channel.
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*/
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notifyIfUpdated(firstResponse, secondResponse, url, cacheName) {
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if (!responsesAreSame(
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firstResponse, secondResponse, this._headersToCheck)) {
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broadcastUpdate(this._getChannel(), cacheName, url, this._source);
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}
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}
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}
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export {BroadcastCacheUpdate};
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