ServiceWorkerContainer.ready

The ready read-only property of the ServiceWorkerContainer interface defines whether a service worker is ready to control a page or not. It returns a Promise that will never reject, which resolves to a ServiceWorkerRegistration with an ServiceWorkerRegistration.active worker.

Syntax

navigator.serviceWorker.ready.then(function(serviceWorkerRegistration) { ... });

Example

function subscribe() {
  var subscribeButton = document.querySelector('.js-subscribe-button');
  subscribeButton.disabled = false;

  navigator.serviceWorker.ready.then(function(serviceWorkerRegistration) {
    serviceWorkerRegistration.pushManager.subscribe()
      .then(function(subscription) {
        // The subscription was successful
        subscribeButton.disabled = true;
        return sendSubscriptionToServer(subscription);
      })
      .catch(function(error) {
        if (Notification.permission === 'denied') {
          console.log('Permission for Notifications was denied');
          subscribeButton.disabled = true;
        } else {
          console.log('Unable to subscribe to push.', error);
          subscribeButton.disabled = false;
        }
      });
  });
}

Specifications

Specification	Status	Comment
Service Workers The definition of 'ServiceWorkerRegistration.ready' in that specification.	Working Draft	Initial definition.

Browser compatibility

[1] Service workers (and Push) have been disabled in the Firefox 45 Extended Support Release (ESR.)