Use alarms to keep service worker running (#299)

ian-h-chamberlain · web-flow · commit 966e02e96ee8 · 2025-03-18T22:45:29.000+08:00
Follow-up to #295, which doesn't seem to be enough to guarantee a good search experience the first time typing. This alarm approach seems to be not recommended, but it works well and can be limited to just run on Firefox where it's an issue. Without a much larger refactor or extensive testing, I think this is truly the best short term solution to using the extension on Firefox!
diff --git a/extension/firefox-bg.html b/extension/firefox-bg.html
@@ -4,6 +4,7 @@
         <meta charset="UTF-8" />
         <title>Rust Search Extension</title>
         <script src="service-worker.js" type="module"></script>
+        <script src="service-worker-keepalive.js" type="module"></script>
   </head>
   <body></body>
 </html>
diff --git a/extension/service-worker-keepalive.js b/extension/service-worker-keepalive.js
@@ -0,0 +1,16 @@
+/**
+ * This is a hack to keep the service worker running forever on Firefox, which
+ * aggressively shuts down the worker on Manifest v3 (resulting in a poor search experience).
+ *
+ * It may be possible to fine-tune the event registration so this isn't necessary,
+ * but it seems like even re-initializing for omnibox.onInputStarted isn't enough to
+ * get suggestions working how they used to in manifest v2.
+ *
+ * See <https://bugzilla.mozilla.org/show_bug.cgi?id=1771203> for more info.
+ **/
+browser.alarms.onAlarm.addListener(() => {
+    // This handler doesn't need to do anything, merely exist.
+});
+
+// Default idle timeout is 30s, this alarm will fire every 20s
+browser.alarms.create("keepalive", { periodInMinutes: 1.0 / 3.0 });
diff --git a/manifest.jsonnet b/manifest.jsonnet
@@ -46,7 +46,7 @@ json
 .addHostPermissions(host_permissions)
 .addOptionalHostPermissions(optional_host_permissions)
 .addIcons(icons())
-.addPermissions(['storage', 'unlimitedStorage'])
+.addPermissions(['storage', 'unlimitedStorage', 'alarms'])
 .setOptionsUi('manage/index.html')
 .addContentScript(
   matches=['*://docs.rs/*'],
