git.r.bdr.sh - rbdr/r.bdr.sh/blob - service_worker.js

   1 'use strict';
   2
   3 const internals = {
   4   version: '4.2.0',
   5   offlineEssentials: [
   6     '/',
   7     '/css/application.css'
   8   ],
   9
  10   // Response for when network is not available
  11
  12   errorResponse: '<h1>Service Unavailable</h1>',
  13
  14   // Main entry point, adds event listeners for service worker
  15
  16   main() {
  17
  18     self.addEventListener('install', internals.onInstall);
  19     self.addEventListener('fetch', internals.onFetch);
  20     self.addEventListener('activate', internals.onActivate);
  21   },
  22
  23   // Runs on installation of the service worker
  24
  25   onInstall(event) {
  26
  27     event.waitUntil(
  28       caches.open(`${internals.version}/essentials`)
  29         .then((cache) => {
  30
  31           return cache.addAll(internals.offlineEssentials)
  32         })
  33     );
  34   },
  35
  36   // Runs when a path is fetched, returns files from cache
  37
  38   onFetch(event) {
  39
  40     if (event.request.method !== 'GET') {
  41       return;
  42     }
  43
  44     event.respondWith(
  45       caches.match(event.request)
  46         .then((cached) => {
  47
  48           const freshContent = fetch(event.request)
  49             .then((response) => {
  50
  51               caches.open(`${internals.version}/paths`)
  52                 .then((cache) => cache.put(event.request, response.clone()));
  53             }, internals.onFetchFail)
  54             .catch(internals.onFetchFail);
  55
  56             return cached || freshContent;
  57         })
  58     );
  59   },
  60
  61   onActivate(event) {
  62
  63     event.waitUntil(
  64       caches.keys()
  65         .then((keys) => {
  66
  67           return Promise.all(keys
  68             .filter((key) => !key.startsWith(internals.version))
  69             .map((key) => caches.delete(key))
  70           );
  71         })
  72     );
  73   },
  74
  75   // Responds with Servie Unavailable if we can't fetch a
  76   // file from network
  77
  78   onFetchFail() {
  79
  80     return new Response(internals.errorResponse, {
  81       status: 503,
  82       statusText: 'Service Unavailable',
  83       headers: new Headers({
  84         'Content-Type': 'text/html'
  85       })
  86     });
  87   }
  88 };
  89
  90 internals.main();