var cacheName = 'tempConverterShell';
var filesToCache = [
 '/',
 '/index.html',
 '/scripts/sample.js',
 '/styles/sample.css'
];
＃install イベントの時　作動　↓
self.addEventListener('install', function(event) {
 console.log('ServiceWorker installing');
 event.waitUntil(
 caches.open(cacheName).then(function(cache) {
 console.log('Service Worker caching app shell');
 return cache.addAll(filesToCache);
 })
 );
});
//activate イベントの時　作動　↓
self.addEventListener('activate', function(event) {
 console.log('Service Worker activating');
 event.waitUntil(
 caches.keys().then(function(keyList) {
 return Promise.all(keyList.map(function(key) {
 if (key !== cacheName) {
 console.log('Service Worker removing oldcache', key);
 return caches.delete(key);
 }
 }));
 })
 );
 return self.clients.claim();
});
//fetch イベントの時　作動　↓
self.addEventListener('fetch', function(event) {
 console.log('Service Worker fetching ',
event.request.url);
 event.respondWith(

caches.match(event.request).then(function(response) {
 return response || fetch(event.request);
 })
 );
});