ServiceWorkerContainer: ready property

Secure contextAvailable in workers

The ready read-only property of the ServiceWorkerContainer interface provides a way of delaying code execution until a service worker is active.

The property returns a Promise that will never reject, and which waits indefinitely until the ServiceWorkerRegistration associated with the current page has an active worker. Once that condition is met, it resolves with the ServiceWorkerRegistration.

Value

A Promise that will never reject, and which may eventually resolve with a ServiceWorkerRegistration when there is an active service worker.

Examples

Deferring code until there is an active service worker

if ("serviceWorker" in navigator) {
  navigator.serviceWorker.ready.then((registration) => {
    console.log(`A service worker is active: ${registration.active}`);

    // At this point, you can call methods that require an active
    // service worker, like registration.pushManager.subscribe()
  });
} else {
  console.error("Service workers are not supported.");
}

Specifications

Browser compatibility