sw_template.js

// Based on https://googlechrome.github.io/samples/service-worker/basic/

const version = "$VERSION$";
const currentCacheName = `ELCWEB-${version}`;
const filesToCache = "$FILES_TO_CACHE$"

self.addEventListener('install', event => {
  event.waitUntil(
    caches.open(currentCacheName)
      .then(cache => cache.addAll(filesToCache))
      .then(self.skipWaiting())
  );
});

self.addEventListener('activate', event => {
  event.waitUntil(
    caches.keys()
      .then(cacheNames => cacheNames.filter(cacheName => ! currentCacheName.includes(cacheName) ))
      .then(cachesToDelete => Promise.all(cachesToDelete.map(cacheToDelete => caches.delete(cacheToDelete))))
      .then(self.clients.claim())
  );
});

self.addEventListener('fetch', event => {
  const url = event.request.url;
  const scope = self.registration.scope;
  
	if (!url.startsWith(scope)) {
		return;
  }

  event.respondWith(
    caches.open(currentCacheName)
      .then(cache => cache.match(event.request, {ignoreSearch: true}) )
      .then(response => response || fetch(event.request) )
  );
});