navigator.serviceWorker is a read-only property that returns the ServiceWorkerContainer for this document — the API entry point to register, update, remove, and talk to service workers (MDN).
Read the notes below before you rely on this property. Prefer feature detection when support is limited.
Use navigator.serviceWorker. Start with this line.
navigator.serviceWorker| Call | What it does |
|---|---|
navigator.serviceWorker | Primary signature. |
Built into the browser. Read navigator.serviceWorker on Navigator — no import required.
navigator.serviceWorker| Parameter | Description |
|---|---|
| Secure context | Required. HTTPS or localhost |
| Return Value | Description |
|---|---|
| * | ServiceWorkerContainer |
MDN’s beginner check before any register call.
if ("serviceWorker" in navigator) {
console.log("Supported!");
} else {
console.log("Service workers are not supported.");
}in operator checks whether the property exists.register() inside the supported branch.Read controller and listen for when a new worker takes over.
if (!("serviceWorker" in navigator)) {
console.log("Service workers are not supported.");
} else if (navigator.serviceWorker.controller) {
console.log("This page is currently controlled by a service worker.");
} else {
console.log("No controlling service worker yet.");
}
if ("serviceWorker" in navigator) {
navigator.serviceWorker.addEventListener("controllerchange", () => {
console.log("Controller changed — a new worker took control.");
});
}controller. A ServiceWorker object means this page is controlled; null means not yet.controller is set (MDN pattern).controllerchange fires when a new active worker takes control.Register a script at the site root (needs a real same-origin /sw.js).
if ("serviceWorker" in navigator) {
navigator.serviceWorker
.register("/sw.js")
.then((registration) => {
console.log("Service worker registration succeeded:", registration.scope);
})
.catch((error) => {
console.error("Service worker registration failed: " + error);
});
} else {
console.log("Service workers are not supported.");
}register without the in check./sw.js).ServiceWorkerRegistration; failure rejects the Promise.sw.js to see success.Navigator.serviceWorker is part of the Service Worker API, marked Baseline Widely available on MDN (since April 2018). Requires a secure context.
Supported in Chrome, Firefox, Safari, Edge, and Opera. Entry point for register(), controller, and ready. May be missing in private mode.
Bottom line: Safe for modern PWAs and offline caching. See the MDN serviceWorker reference. Always feature-detect and serve over HTTPS.
Learn how navigator.storage estimates quota and requests persistent storage.
14 people found this page helpful