sw.js

var CACHE = "v1.1"

var filesToCache = [
  './',
  './resources/js/jquery.min.js',
  './resources/js/highlight.min.js',
  './resources/js/json-to-nest.js',
  './resources/js/common.js',
  './resources/css/tomorrow.highlight.css',
  './resources/css/common.css',
  'https://d33wubrfki0l68.cloudfront.net/e937e774cbbe23635999615ad5d7732decad182a/26072/logo-small.ede75a6b.svg'
]

self.addEventListener('install', function (evt) {
  console.log('Attempting service worker installation.');

  // Wait until promise resolves
  evt.waitUntil(precache());
});

// On fetch, return from cache
self.addEventListener('fetch', function (evt) {
  evt.respondWith(serve(evt.request));
});

// Opens cache and loads filesToCache into cache for using them in future
function precache() {
  return caches
    .open(CACHE)
    .then(function (cache) {
      return cache.addAll(filesToCache);
    });
}

// When a resource is requested first serve from service worker and if service
// worker hasn't cached that request, then fetch that resource and then serve it
// This strategy is cache first.
function serve(request) {
  return caches
    .open(CACHE)
    .then(function (cache) {
      return cache
        .match(request)
        .then(function (matching) {
          return matching || fetch(request);
        })
        .catch(console.error);
    });
}