workbox/test/workbox-google-analytics/static/basic-example/sw.js

/*
  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.
*/

importScripts('/__WORKBOX/buildFile/workbox-sw');
importScripts('/infra/testing/comlink/sw-interface.js');

workbox.setConfig({modulePathPrefix: '/__WORKBOX/buildFile/'});

const sleep = async (ms) => {
  return new Promise((resolve) => setTimeout(resolve, ms));
};

// Spy on .fetch() calls from inside the service worker.
// If `simulateOffline` is set to true, throw a network error.
let simulateOffline = false;
let spiedRequests = [];
const originalFetch = self.fetch;
self.fetch = async (...args) => {
  if (simulateOffline) {
    // Simulate network latency, so the sync event doesn't just fire
    // in an endless loop.
    await sleep(100);
    throw new Error('Simulated network error');
  }
  const clone =
    args[0] instanceof Request ? args[0].clone() : new Request(args[0]);

  spiedRequests.push({
    url: clone.url,
    timestamp: Date.now(),
    body: await clone.text(),
  });
  return originalFetch(...args);
};

// Add a message listener for communication between the client and SW.
self.addEventListener('message', (evt) => {
  switch (evt.data.action) {
    case 'simulate-offline':
      simulateOffline = evt.data.value;
      evt.ports[0].postMessage(null);
      break;
    case 'clear-spied-requests':
      spiedRequests = [];
      evt.ports[0].postMessage(null);
      break;
    case 'get-spied-requests':
      evt.ports[0].postMessage(spiedRequests);
      break;
    case 'dispatch-sync-event': {
      // Override `.waitUntil` so we can signal when the sync is done.
      const originalSyncEventWaitUntil = SyncEvent.prototype.waitUntil;
      SyncEvent.prototype.waitUntil = (promise) => {
        return promise.then(() => evt.ports[0].postMessage(null));
      };

      self.dispatchEvent(
        new SyncEvent('sync', {
          tag: 'workbox-background-sync:workbox-google-analytics',
        }),
      );
      SyncEvent.prototype.waitUntil = originalSyncEventWaitUntil;
      break;
    }
  }
});

workbox.googleAnalytics.initialize();

self.addEventListener('install', (evt) => evt.waitUntil(self.skipWaiting()));
self.addEventListener('activate', (evt) => evt.waitUntil(self.clients.claim()));