48 lines
1.8 KiB
JavaScript
48 lines
1.8 KiB
JavaScript
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/*
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Copyright 2020 Google LLC
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Use of this source code is governed by an MIT-style
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license that can be found in the LICENSE file or at
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https://opensource.org/licenses/MIT.
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*/
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import { getOrCreatePrecacheController } from './utils/getOrCreatePrecacheController.js';
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import './_version.js';
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/**
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* `PrecacheFallbackPlugin` allows you to specify an "offline fallback"
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* response to be used when a given strategy is unable to generate a response.
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*
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* It does this by intercepting the `handlerDidError` plugin callback
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* and returning a precached response, taking the expected revision parameter
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* into account automatically.
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*
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* Unless you explicitly pass in a `PrecacheController` instance to the
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* constructor, the default instance will be used. Generally speaking, most
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* developers will end up using the default.
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*
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* @memberof workbox-precaching
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*/
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class PrecacheFallbackPlugin {
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/**
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* Constructs a new PrecacheFallbackPlugin with the associated fallbackURL.
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*
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* @param {Object} config
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* @param {string} config.fallbackURL A precached URL to use as the fallback
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* if the associated strategy can't generate a response.
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* @param {PrecacheController} [config.precacheController] An optional
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* PrecacheController instance. If not provided, the default
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* PrecacheController will be used.
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*/
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constructor({ fallbackURL, precacheController, }) {
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/**
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* @return {Promise<Response>} The precache response for the fallback URL.
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*
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* @private
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*/
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this.handlerDidError = () => this._precacheController.matchPrecache(this._fallbackURL);
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this._fallbackURL = fallbackURL;
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this._precacheController =
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precacheController || getOrCreatePrecacheController();
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}
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}
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export { PrecacheFallbackPlugin };
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