ServiceWorkerContainer: controller property

Baseline Widely available

This feature is well established and works across many devices and browser versions. It’s been available across browsers since April 2018.

Secure context: This feature is available only in secure contexts (HTTPS), in some or all supporting browsers.

Note: This feature is available in Web Workers.

The controller read-only property of the ServiceWorkerContainer interface returns a ServiceWorker object if its state is activating or activated (the same object returned by ServiceWorkerRegistration.active). This property returns null if the request is a force refresh (Shift + refresh) or if there is no active worker.

Value

A ServiceWorker object.

Examples

js
if ("serviceWorker" in navigator) {
  // Do a one-off check to see if a service worker's in control.
  if (navigator.serviceWorker.controller) {
    console.log(
      `This page is currently controlled by: ${navigator.serviceWorker.controller}`,
    );
  } else {
    console.log("This page is not currently controlled by a service worker.");
  }
} else {
  console.log("Service workers are not supported.");
}

Specifications

Specification
Service Workers
# navigator-service-worker-controller

Browser compatibility