From af5cd7e548447b6aa86b34b069cc4e88c0fd1256 Mon Sep 17 00:00:00 2001
From: Guo Xiang Tan <tgx_world@hotmail.com>
Date: Thu, 5 Jul 2018 14:57:32 +0800
Subject: [PATCH] Unregister old service workers when
 `Discourse.ServiceWorkerURL` changes.

---
 .../initializers/register-service-worker.js.es6     | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/app/assets/javascripts/discourse/initializers/register-service-worker.js.es6 b/app/assets/javascripts/discourse/initializers/register-service-worker.js.es6
index d5c6c460c3f..26d19206ffe 100644
--- a/app/assets/javascripts/discourse/initializers/register-service-worker.js.es6
+++ b/app/assets/javascripts/discourse/initializers/register-service-worker.js.es6
@@ -11,6 +11,19 @@ export default {
 
     if (isSupported) {
       if (Discourse.ServiceWorkerURL && !isSafari) {
+        navigator.serviceWorker.getRegistrations().then(registrations => {
+          for (let registration of registrations) {
+            if (
+              registration.active &&
+              !registration.active.scriptURL.includes(
+                Discourse.ServiceWorkerURL
+              )
+            ) {
+              registration.unregister();
+            }
+          }
+        });
+
         navigator.serviceWorker
           .register(`${Discourse.BaseUri}/${Discourse.ServiceWorkerURL}`)
           .catch(error => {