sw.js

var CACHE_NAME = "expense-manager-cache";
var urlsToCache = [
  "style.css",
  "icons/favicon-32x32.png",
  "icons/favicon-16x16.png",
  "init.js",
  "transfer.js",
  "utils.js",
  "expense.js",
  "vendor/mdl/material.min.js",
  "vendor/mdl/material.min.css"
];

// cache after the first install
self.addEventListener("install", function(event) {
  // Perform install steps
  event.waitUntil(
    caches.open(CACHE_NAME).then(function(cache) {
      console.log("Opened cache");
      return cache.addAll(urlsToCache);
    })
  );
});

// listen for fetch events
self.addEventListener("fetch", function(event) {
  const requestURL = new URL(event.request.url);
  event.respondWith(
    caches.open(CACHE_NAME).then(function(cache) {
      return caches.match(event.request).then(function(response) {
        var fetchPromise = fetch(event.request).then(function(networkResponse) {
          // cache same host files only
          if (
            requestURL.hostname === "mitul45.github.io" ||
            requestURL.hostname === "localhost"
          )
            cache.put(event.request, networkResponse.clone());
          return networkResponse;
        });
        return response || fetchPromise;
      });
    })
  );
});