ServiceWorkerContainer: controller property

Secure contextAvailable in workers

The controller read-only property of the ServiceWorkerContainer interface represents the active service worker controlling the current page (associated with this ServiceWorkerContainer), or null if the page has no active or activating service worker.

This is the same object returned by active.

Value

A ServiceWorker object if its state is activating or activated, or null if there is no active worker.

The property also returns null if the request is a force refresh (Shift + refresh)

Examples

Test if a page is controlled by a service worker

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

Browser compatibility