Service Workers Cached JS

offline.svg

<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 22 22">
  <defs id="defs3051">
    <style type="text/css" id="current-color-scheme">
      .ColorScheme-Text {
        color:#4d4d4d;
      }
      </style>
  </defs>
  <g
     transform="translate(-421.71429,-525.79074)">
    <path
       style="opacity:1;fill:currentColor;fill-opacity:1;stroke:none"
       d="M 11 4 A 6 6 0 0 0 5 10 A 6 6 0 0 0 5.0039062 10.128906 A 4 4 0 0 0 2 14 A 4 4 0 0 0 6 18 L 15 18 A 5 5 0 0 0 20 13 A 5 5 0 0 0 16.757812 8.3242188 A 6 6 0 0 0 11 4 z M 11 5 A 5 5 0 0 1 15.919922 9.1113281 A 4.0000019 4.0000019 0 0 1 19 13 A 4.0000019 4.0000019 0 0 1 15 17 L 6 17 A 2.9999979 2.9999979 0 0 1 3 14 A 2.9999979 2.9999979 0 0 1 6 11 A 2.9999979 2.9999979 0 0 1 6.1074219 11.005859 A 5 5 0 0 1 6 10 A 5 5 0 0 1 11 5 z "
       transform="translate(421.71429,525.79074)"
       class="ColorScheme-Text"
       id="path4196" />
    <path
       style="opacity:1;fill:#bdc3c7;fill-opacity:1;stroke:none"
       d="m 442.71429,540.29071 a 4.5,4.5 0 0 1 -4.5,4.5 4.5,4.5 0 0 1 -4.5,-4.5 4.5,4.5 0 0 1 4.5,-4.5 4.5,4.5 0 0 1 4.5,4.5 z"
       id="path4306" />
    <path
       style="opacity:1;fill:#ffffff;fill-opacity:1;stroke-linecap:round"
       d="M 14 14 L 14 15 L 15 15 L 15 14 L 14 14 z M 16 14 L 16 15 L 17 15 L 17 14 L 16 14 z M 18 14 L 18 15 L 19 15 L 19 14 L 18 14 z "
       transform="translate(421.71429,525.79074)"
       id="rect4521" />
  </g>
</svg>

sw.js

'use strict';
const version = 'v201704100047';
const __DEVELOPMENT__ = false;
const __DEBUG__ = false;
const offlineResources = ['/', '/offline.html', '/offline.svg'];
const ignoreFetch = [/https?:\/\/example.disqus.com\//, /chrome-extension:\/\//];

function onInstall(event) {
	log('install event in progress.');
	event.waitUntil(updateStaticCache());
	self.skipWaiting()
}
function updateStaticCache() {
	return caches.open(cacheKey('offline')).then((cache) = > {
		return cache.addAll(offlineResources)
	}).then(() = > {
		log('installation complete!')
	})
}
function onFetch(event) {
	const request = event.request;
	if (shouldAlwaysFetch(request)) {
		event.respondWith(networkedOrOffline(request));
		return
	}
	if (shouldFetchAndCache(request)) {
		event.respondWith(networkedOrCached(request));
		return
	}
	event.respondWith(cachedOrNetworked(request))
}
function networkedOrCached(request) {
	return networkedAndCache(request).
	catch (() = > {
		return cachedOrOffline(request)
	})
}
function networkedAndCache(request) {
	return fetch(request).then((response) = > {
		var copy = response.clone();
		caches.open(cacheKey('resources')).then((cache) = > {
			cache.put(request, copy)
		});
		log("(network: cache write)", request.method, request.url);
		return response
	})
}
function cachedOrNetworked(request) {
	return caches.match(request).then((response) = > {
		log(response ? '(cached)' : '(network: cache miss)', request.method, request.url);
		return response || networkedAndCache(request).
		catch (() = > {
			return offlineResponse(request)
		})
	})
}
function networkedOrOffline(request) {
	return fetch(request).then((response) = > {
		log('(network)', request.method, request.url);
		return response
	}).
	catch (() = > {
		return offlineResponse(request)
	})
}
function cachedOrOffline(request) {
	return caches.match(request).then((response) = > {
		return response || offlineResponse(request)
	})
}
function offlineResponse(request) {
	log('(offline)', request.method, request.url);
	if (request.url.match(/\.(jpg|png|gif|svg|jpeg)(\?.*)?$/)) {
		return caches.match('/offline.svg')
	} else {
		return caches.match('/offline.html')
	}
}
function onActivate(event) {
	log('activate event in progress.');
	event.waitUntil(removeOldCache())
}
function removeOldCache() {
	return caches.keys().then((keys) = > {
		return Promise.all(keys.filter((key) = > {
			return !key.startsWith(version)
		}).map((key) = > {
			return caches.delete(key)
		}))
	}).then(() = > {
		log('removeOldCache completed.')
	})
}
function cacheKey() {
	return [version, ...arguments].join(':')
}
function log() {
	if (developmentMode()) {
		console.log("SW:", ...arguments)
	}
}
function shouldAlwaysFetch(request) {
	return __DEVELOPMENT__ || request.method !== 'GET' || ignoreFetch.some(regex = > request.url.match(regex))
}
function shouldFetchAndCache(request) {
	return ~request.headers.get('Accept').indexOf('text/html')
}
function developmentMode() {
	return __DEVELOPMENT__ || __DEBUG__
}
log("Hello from ServiceWorker land!", version);
self.addEventListener('install', onInstall);
self.addEventListener('fetch', onFetch);
self.addEventListener("activate", onActivate);