https://docs.microsoft.com/en-us/aspnet/core/blazor/progressive-web-app

PWA without offline support

src/BlazorBoilerplate.Server/wwwroot/index_csb.html

@@ -19,7 +19,8 @@
     <link href="_content/BlazorBoilerplate.CommonUI/css/bootstrap/bootstrap.min.css" rel="stylesheet" />
     <link href="_content/MatBlazor/dist/matBlazor.css" rel="stylesheet" />
     <link href="_content/BlazorBoilerplate.CommonUI/css/site.css" rel="stylesheet" />
-
+    <link href="manifest.json" rel="manifest" />
+
     <!-- Global site tag (gtag.js) - Google Analytics -->
     <script async src="https://www.googletagmanager.com/gtag/js?id=UA-55161075-2"></script>
     <script>
@@ -58,5 +59,8 @@
     <script src="_content/BlazorBoilerplate.CommonUI/javascript/chatClient.js"></script>
     <script src="_content/BlazorBoilerplate.CommonUI/javascript/jsInterops.js"></script>
     <script src="_content/Microsoft.AspNetCore.ProtectedBrowserStorage/protectedBrowserStorage.js"></script>
+
+    <!-- https://docs.microsoft.com/en-us/aspnet/core/blazor/progressive-web-app -->
+    <script>navigator.serviceWorker.register('service-worker.js');</script>
 </body>
 </html>

src/BlazorBoilerplate.Server/wwwroot/manifest.json

@@ -0,0 +1,15 @@
+{
+  "name": "Blazor Boilerplate & Starter Kit (CSB)",
+  "short_name": "Blazor Boilerplate",
+  "start_url": "/",
+  "display": "standalone",
+  "background_color": "#ffffff",
+  "theme_color": "#5D2E8F",
+  "icons": [
+    {
+      "src": "icon-512.png",
+      "type": "image/png",
+      "sizes": "512x512"
+    }
+  ]
+}

src/BlazorBoilerplate.Server/wwwroot/service-worker.js

@@ -0,0 +1,4 @@
+// In development, always fetch from the network and do not enable offline support.
+// This is because caching would make development more difficult (changes would not
+// be reflected on the first load after each change).
+self.addEventListener('fetch', () => { });

src/BlazorBoilerplate.Server/wwwroot/service-worker.published.js

@@ -0,0 +1,48 @@
+// Caution! Be sure you understand the caveats before publishing an application with
+// offline support. See https://aka.ms/blazor-offline-considerations
+
+self.importScripts('./service-worker-assets.js');
+self.addEventListener('install', event => event.waitUntil(onInstall(event)));
+self.addEventListener('activate', event => event.waitUntil(onActivate(event)));
+self.addEventListener('fetch', event => event.respondWith(onFetch(event)));
+
+const cacheNamePrefix = 'offline-cache-';
+const cacheName = `${cacheNamePrefix}${self.assetsManifest.version}`;
+const offlineAssetsInclude = [ /\.dll$/, /\.pdb$/, /\.wasm/, /\.html/, /\.js$/, /\.json$/, /\.css$/, /\.woff$/, /\.png$/, /\.jpe?g$/, /\.gif$/, /\.ico$/ ];
+const offlineAssetsExclude = [ /^service-worker\.js$/ ];
+
+async function onInstall(event) {
+    console.info('Service worker: Install');
+
+    // Fetch and cache all matching items from the assets manifest
+    const assetsRequests = self.assetsManifest.assets
+        .filter(asset => offlineAssetsInclude.some(pattern => pattern.test(asset.url)))
+        .filter(asset => !offlineAssetsExclude.some(pattern => pattern.test(asset.url)))
+        .map(asset => new Request(asset.url, { integrity: asset.hash }));
+    await caches.open(cacheName).then(cache => cache.addAll(assetsRequests));
+}
+
+async function onActivate(event) {
+    console.info('Service worker: Activate');
+
+    // Delete unused caches
+    const cacheKeys = await caches.keys();
+    await Promise.all(cacheKeys
+        .filter(key => key.startsWith(cacheNamePrefix) && key !== cacheName)
+        .map(key => caches.delete(key)));
+}
+
+async function onFetch(event) {
+    let cachedResponse = null;
+    if (event.request.method === 'GET') {
+        // For all navigation requests, try to serve index.html from cache
+        // If you need some URLs to be server-rendered, edit the following check to exclude those URLs
+        const shouldServeIndexHtml = event.request.mode === 'navigate';
+
+        const request = shouldServeIndexHtml ? 'index.html' : event.request;
+        const cache = await caches.open(cacheName);
+        cachedResponse = await cache.match(request);
+    }
+
+    return cachedResponse || fetch(event.request);
+}