workbox-precaching/src/utils/PrecacheInstallReportPlugin.ts

This module efficiently precaches assets.

/*
  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 {WorkboxPlugin, WorkboxPluginCallbackParam} from 'workbox-core/types.js';

import '../_version.js';


/**
 * A plugin, designed to be used with PrecacheController, to determine the
 * of assets that were updated (or not updated) during the install event.
 * 
 * @private
 */
class PrecacheInstallReportPlugin implements WorkboxPlugin {
  updatedURLs: string[] = [];
  notUpdatedURLs: string[] = [];

  handlerWillStart: WorkboxPlugin['handlerWillStart'] = async ({
    request,
    state,
  }: WorkboxPluginCallbackParam['handlerWillStart']) => {
    // TODO: `state` should never be undefined...
    if (state) {
      state.originalRequest = request;
    }
  }

  cachedResponseWillBeUsed: WorkboxPlugin['cachedResponseWillBeUsed'] = async ({
    event,
    state,
    cachedResponse,
  }: WorkboxPluginCallbackParam['cachedResponseWillBeUsed']) => {
    if (event.type === 'install') {
      // TODO: `state` should never be undefined...
      const url = state!.originalRequest.url;

      if (cachedResponse) {
        this.notUpdatedURLs.push(url);
      } else {
        this.updatedURLs.push(url);
      }
    }
    return cachedResponse;
  }
}

export {PrecacheInstallReportPlugin};