ServiceWorkerContainer

The ServiceWorkerContainer interface of the ServiceWorker API provides an object representing the service worker as an overall unit in the network ecosystem, including facilities to register, unregister and update service workers, and access the state of service workers and their registrations.

Most importantly, it exposes the ServiceWorkerContainer.register(scriptURL, scope[, base]) method used to register service workers, and the ServiceWorkerContainer.controller property used to determine whether or not the current page is actively controlled.

ServiceWorkerContainer.controller Read only

Returns a ServiceWorker object if its state is 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.

ServiceWorkerContainer.ready Read only

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.

ServiceWorkerContainer.oncontrollerchange

An event handler fired whenever a controllerchange event occurs — when the document's associated ServiceWorkerRegistration acquires a new ServiceWorkerRegistration.active worker.

ServiceWorkerContainer.onerror

An event handler fired whenever an error event occurs in the associated service workers.

ServiceWorkerContainer.onmessage

An event handler fired whenever a message event occurs — when incoming messages are received to the ServiceWorkerContainer object (e.g. via a MessagePort.postMessage() call.)

ServiceWorkerContainer.register() 

Creates or updates a ServiceWorkerRegistration for the given scriptURL.

ServiceWorkerContainer.getRegistration()

Gets a ServiceWorkerRegistration object whose scope URL matches the provided document URL.  If the method can't return a ServiceWorkerRegistration, it returns a Promise. 

ServiceWorkerContainer.getRegistrations()

Returns all ServiceWorkerRegistrations associated with a ServiceWorkerContainer in an array.  If the method can't return ServiceWorkerRegistrations, it returns a Promise. 

This code snippet is from the service worker fallback-response sample (see fallback-response live). The code checks to see if the browser supports service workers. Then the code registers the service worker and determines if the page is actively controlled by the service worker. If it isn't, it prompts the user to reload the page so the service worker can take control. The code also reports any registration failures.

if ('serviceWorker' in navigator) {
  navigator.serviceWorker.register('service-worker.js', {scope: './'}).then(function() {
    if (navigator.serviceWorker.controller) {
      document.querySelector('#status').textContent = 'The service worker is currently handling network operations.';
      showRequestButtons();
    } else {
      document.querySelector('#status').textContent = 'Please reload this page to allow the service worker to handle network operations.';
    }
  }).catch(function(error) {
    document.querySelector('#status').textContent = error;
  });
} else {
  var aElement = document.createElement('a');
  aElement.href = 'http://www.chromium.org/blink/serviceworker/service-worker-faq';
  aElement.textContent = 'unavailable';
  document.querySelector('#status').appendChild(aElement);
}

• Using Service Workers
• Service workers basic code example
• Is ServiceWorker ready?
• Promise
• Using web workers