diff --git a/demo/public/service_worker.js b/demo/public/service_worker.js
index e69de29bb2..9cd535c9fc 100644
--- a/demo/public/service_worker.js
+++ b/demo/public/service_worker.js
@@ -0,0 +1,3 @@
+self.addEventListener("fetch", function(event) {
+  event.respondWith(fetch(event.request));
+});