sw.js

// This polyfill provides Cache.add(), Cache.addAll(), and CacheStorage.match()
importScripts('sw-cache-polyfill.js');

//my SW
this.addEventListener('install', function(event){
    event.waitUntil(
        caches.open('v1').then(function(cache){
            return cache.addAll([
                '/ngitung/',
                '/ngitung/index.html',
                '/ngitung/style.css',
                '/ngitung/app.js'
            ]);
        })
    );
})
this.addEventListener('fetch', function(event) {
    var response;
    event.respondWith(caches.match(event.request).catch(function() {
        return fetch(event.request);
    }).then(function(r) {
            response = r;
            caches.open('v1').then(function(cache) {
                cache.put(event.request, response);
    });
        return response.clone();
  }).catch(function() {
    return caches.match('/ngitung/index.html');
  }));
});