samples/web/slide_puzzle/flutter_service_worker.js

'use strict';
const MANIFEST = 'flutter-app-manifest';
const TEMP = 'flutter-temp-cache';
const CACHE_NAME = 'flutter-app-cache';
const RESOURCES = {
  "icons/Icon-512.png": "70dd4c7d62910514def11f21e23d99f8",
"icons/favicon.png": "fa7fde306a35e196516bf8b1d6100f14",
"icons/Icon-192.png": "8afa706053b186edf013b6c9880872f9",
"manifest.json": "c58884a2d51c23985850658029a90226",
"assets/AssetManifest.json": "530ce7513a29f7e0e810e7b74f70931f",
"assets/assets/images/simple_dash_large.png": "c3100434238b1fe0f6b8e6d074ccd80e",
"assets/assets/images/simple_dash_medium.png": "4e2fd9dee5fbd150653f06a83be3accf",
"assets/assets/images/simple_dash_small.png": "b3f2ec92db7be8297f529f94d8e38136",
"assets/assets/images/shuffle_icon.png": "32ebb4a7c6f9b07157a57f537f254619",
"assets/assets/fonts/GoogleSans-Regular.ttf": "51134713ade7b1f137e06ce395d39d40",
"assets/assets/fonts/GoogleSans-BoldItalic.ttf": "aebc8fe5e393970fa3d468524e64b670",
"assets/assets/fonts/GoogleSans-Bold.ttf": "c0370e8a74992bab73461f8348e3b369",
"assets/assets/fonts/GoogleSans-Italic.ttf": "b08c7421b2d5350ea3003c8f38932601",
"assets/NOTICES": "57acdf72b543bf647caed8c82ab5f10a",
"assets/FontManifest.json": "a6a35a39ab693849dcde3aba2d4304a7",
"assets/fonts/MaterialIcons-Regular.otf": "4e6447691c9509f7acdbf8a931a85ca1",
"index.html": "bf2ae2a8e3add87afd231227b24a1ccb",
"/": "bf2ae2a8e3add87afd231227b24a1ccb",
"version.json": "edac6610d63f93aebfb1c09a76230248",
"favicon.png": "fa7fde306a35e196516bf8b1d6100f14",
"main.dart.js": "61754a901cc48bc501a7c145d08639b5",
"canvaskit/profiling/canvaskit.js": "f3bfccc993a1e0bfdd3440af60d99df4",
"canvaskit/profiling/canvaskit.wasm": "a9610cf39260f60fbe7524a785c66101",
"canvaskit/canvaskit.js": "43fa9e17039a625450b6aba93baf521e",
"canvaskit/canvaskit.wasm": "04ed3c745ff1dee16504be01f9623498"
};

// The application shell files that are downloaded before a service worker can
// start.
const CORE = [
  "/",
"main.dart.js",
"index.html",
"assets/NOTICES",
"assets/AssetManifest.json",
"assets/FontManifest.json"];
// During install, the TEMP cache is populated with the application shell files.
self.addEventListener("install", (event) => {
  self.skipWaiting();
  return event.waitUntil(
    caches.open(TEMP).then((cache) => {
      return cache.addAll(
        CORE.map((value) => new Request(value, {'cache': 'reload'})));
    })
  );
});

// During activate, the cache is populated with the temp files downloaded in
// install. If this service worker is upgrading from one with a saved
// MANIFEST, then use this to retain unchanged resource files.
self.addEventListener("activate", function(event) {
  return event.waitUntil(async function() {
    try {
      var contentCache = await caches.open(CACHE_NAME);
      var tempCache = await caches.open(TEMP);
      var manifestCache = await caches.open(MANIFEST);
      var manifest = await manifestCache.match('manifest');
      // When there is no prior manifest, clear the entire cache.
      if (!manifest) {
        await caches.delete(CACHE_NAME);
        contentCache = await caches.open(CACHE_NAME);
        for (var request of await tempCache.keys()) {
          var response = await tempCache.match(request);
          await contentCache.put(request, response);
        }
        await caches.delete(TEMP);
        // Save the manifest to make future upgrades efficient.
        await manifestCache.put('manifest', new Response(JSON.stringify(RESOURCES)));
        return;
      }
      var oldManifest = await manifest.json();
      var origin = self.location.origin;
      for (var request of await contentCache.keys()) {
        var key = request.url.substring(origin.length + 1);
        if (key == "") {
          key = "/";
        }
        // If a resource from the old manifest is not in the new cache, or if
        // the MD5 sum has changed, delete it. Otherwise the resource is left
        // in the cache and can be reused by the new service worker.
        if (!RESOURCES[key] || RESOURCES[key] != oldManifest[key]) {
          await contentCache.delete(request);
        }
      }
      // Populate the cache with the app shell TEMP files, potentially overwriting
      // cache files preserved above.
      for (var request of await tempCache.keys()) {
        var response = await tempCache.match(request);
        await contentCache.put(request, response);
      }
      await caches.delete(TEMP);
      // Save the manifest to make future upgrades efficient.
      await manifestCache.put('manifest', new Response(JSON.stringify(RESOURCES)));
      return;
    } catch (err) {
      // On an unhandled exception the state of the cache cannot be guaranteed.
      console.error('Failed to upgrade service worker: ' + err);
      await caches.delete(CACHE_NAME);
      await caches.delete(TEMP);
      await caches.delete(MANIFEST);
    }
  }());
});

// The fetch handler redirects requests for RESOURCE files to the service
// worker cache.
self.addEventListener("fetch", (event) => {
  if (event.request.method !== 'GET') {
    return;
  }
  var origin = self.location.origin;
  var key = event.request.url.substring(origin.length + 1);
  // Redirect URLs to the index.html
  if (key.indexOf('?v=') != -1) {
    key = key.split('?v=')[0];
  }
  if (event.request.url == origin || event.request.url.startsWith(origin + '/#') || key == '') {
    key = '/';
  }
  // If the URL is not the RESOURCE list then return to signal that the
  // browser should take over.
  if (!RESOURCES[key]) {
    return;
  }
  // If the URL is the index.html, perform an online-first request.
  if (key == '/') {
    return onlineFirst(event);
  }
  event.respondWith(caches.open(CACHE_NAME)
    .then((cache) =>  {
      return cache.match(event.request).then((response) => {
        // Either respond with the cached resource, or perform a fetch and
        // lazily populate the cache.
        return response || fetch(event.request).then((response) => {
          cache.put(event.request, response.clone());
          return response;
        });
      })
    })
  );
});

self.addEventListener('message', (event) => {
  // SkipWaiting can be used to immediately activate a waiting service worker.
  // This will also require a page refresh triggered by the main worker.
  if (event.data === 'skipWaiting') {
    self.skipWaiting();
    return;
  }
  if (event.data === 'downloadOffline') {
    downloadOffline();
    return;
  }
});

// Download offline will check the RESOURCES for all files not in the cache
// and populate them.
async function downloadOffline() {
  var resources = [];
  var contentCache = await caches.open(CACHE_NAME);
  var currentContent = {};
  for (var request of await contentCache.keys()) {
    var key = request.url.substring(origin.length + 1);
    if (key == "") {
      key = "/";
    }
    currentContent[key] = true;
  }
  for (var resourceKey of Object.keys(RESOURCES)) {
    if (!currentContent[resourceKey]) {
      resources.push(resourceKey);
    }
  }
  return contentCache.addAll(resources);
}

// Attempt to download the resource online before falling back to
// the offline cache.
function onlineFirst(event) {
  return event.respondWith(
    fetch(event.request).then((response) => {
      return caches.open(CACHE_NAME).then((cache) => {
        cache.put(event.request, response.clone());
        return response;
      });
    }).catch((error) => {
      return caches.open(CACHE_NAME).then((cache) => {
        return cache.match(event.request).then((response) => {
          if (response != null) {
            return response;
          }
          throw error;
        });
      });
    })
  );
}