Fetch Brotli-precompressed framework files

Author: SteveSandersonMS

wwwroot/decode.js

@@ -50,19 +50,24 @@
         <a href="" class="reload">Reload</a>
         <a class="dismiss">🗙</a>
     </div>
-
+    <script src="decode.js"></script>
     <script src="_framework/blazor.webassembly.js" autostart="false"></script>
     <script>
         Blazor.start({
             loadBootResource: function (type, name, defaultUri, integrity) {
-                // For framework resources, use the precompressed .gz files for faster downloads
-                // This is needed only because GitHub pages doesn't natively support response compression for .dll files
-                if (type === 'assembly') {
+                // For framework resources, use the precompressed .br files for faster downloads
+                // This is needed only because GitHub pages doesn't natively support Brotli (or even gzip for .dll files)
+                if (type !== 'dotnetjs' && location.hostname !== 'localhost') {
                     return (async function () {
-                        const response = await fetch(defaultUri + '.gz', { cache: 'no-cache' });
-                        const originalResponseBlob = await response.blob();
-                        const decompressedStream = originalResponseBlob.stream().pipeThrough(new DecompressionStream('gzip'));
-                        return new Response(decompressedStream, { headers: response.headers });
+                        const response = await fetch(defaultUri + '.br', { cache: 'no-cache' });
+                        if (!response.ok) {
+                            throw new Error(response.statusText);
+                        }
+                        const originalResponseBuffer = await response.arrayBuffer();
+                        const originalResponseArray = new Int8Array(originalResponseBuffer);
+                        const decompressedResponseArray = BrotliDecode(originalResponseArray);
+                        const contentType = type === 'dotnetwasm' ? 'application/wasm' : 'application/octet-stream';
+                        return new Response(decompressedResponseArray, { headers: { 'content-type': contentType } });
                     })();
                 }
             }