files/en-us/web/http/reference/headers/service-worker-allowed/index.md
The HTTP Service-Worker-Allowed {{Glossary("response header")}} is used to broaden the path restriction for a service worker's default scope.
By default, the scope for a service worker registration is the directory where the service worker script is located.
For example, if the script sw.js is located in /js/sw.js, it can only control URLs under /js/ by default.
Servers can use the Service-Worker-Allowed header to allow a service worker to control URLs outside of its own directory.
A service worker intercepts all network requests within its scope, so you should avoid using overly-broad scopes unless necessary.
<table class="properties"> <tbody> <tr> <th scope="row">Header type</th> <td>{{Glossary("Response header")}}</td> </tr> </tbody> </table>Service-Worker-Allowed: <scope>
<scope>
The JavaScript example below is included in example.com/product/index.html, and attempts to register a service worker with a scope that applies to all resources under example.com/.
navigator.serviceWorker.register("./sw.js", { scope: "/" }).then(
(registration) => {
console.log("Install succeeded, scoped to '/'", registration);
},
(error) => {
console.error(`Service worker registration failed: ${error}`);
},
);
The HTTP response to the service worker's script resource request (./sw.js) includes the Service-Worker-Allowed header set to /:
HTTP/1.1 200 OK
Date: Mon, 16 Dec 2024 14:37:20 GMT
Service-Worker-Allowed: /
// sw.js contents…
If the server doesn't set the header, the service worker registration will fail, as the scope option ({ scope: "/" }) requests a scope broader than the directory where the service worker script is located (/product/sw.js).
{{Specifications}}
{{Compat}}