ServiceWorkerContainer

ServiceWorkerContainer.controller (en-US) Read only

Returns a ServiceWorker (en-US) object if its state is activated (the same object returned by ServiceWorkerRegistration.active (en-US)). This property returns null during a force-refresh request (Shift + refresh) or if there is no active worker.

ServiceWorkerContainer.ready (en-US) Read only

Provides a way of delaying code execution until a service worker is active. It returns a Promise that will never reject, and which waits indefinitely until the ServiceWorkerRegistration (en-US) associated with the current page has an ServiceWorkerRegistration.active (en-US) worker. Once that condition is met, it resolves with the ServiceWorkerRegistration (en-US).

ServiceWorkerContainer.oncontrollerchange (en-US)

Fired whenever a controllerchange event occurs — when the document's associated ServiceWorkerRegistration (en-US) acquires a new active (en-US) worker.

ServiceWorkerContainer.onerror (en-US)

Fired whenever an error (en-US) event occurs in the associated service workers.

ServiceWorkerContainer.onmessage (en-US)

Fired whenever a message event occurs — when incoming messages are received to the ServiceWorkerContainer object (e.g. via a MessagePort.postMessage() (en-US) call.)

ServiceWorkerContainer.register()

Creates or updates a ServiceWorkerRegistration (en-US) for the given scriptURL.

ServiceWorkerContainer.getRegistration() (en-US)

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

ServiceWorkerContainer.getRegistrations() (en-US)

Returns all ServiceWorkerRegistration (en-US) objects associated with a ServiceWorkerContainer in an array. If the method can't return ServiceWorkerRegistration (en-US) objects, it returns a Promise.

The example below first checks to see if the browser supports service workers. If supported, 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) {
  // Register a service worker hosted at the root of the
  // site using the default scope.
  navigator.serviceWorker.register('/sw.js').then(function(registration) {
    console.log('Service worker registration succeeded:', registration);

    // At this point, you can optionally do something
    // with registration. See https://developer.mozilla.org/en-US/docs/Web/API/ServiceWorkerRegistration
  }).catch(function(error) {
    console.log('Service worker registration failed:', error);
  });

  // Independent of the registration, let's also display
  // information about whether the current page is controlled
  // by an existing service worker, and when that
  // controller changes.

  // First, do a one-off check if there's currently a
  // service worker in control.
  if (navigator.serviceWorker.controller) {
    console.log('This page is currently controlled by:', navigator.serviceWorker.controller);
  }

  // Then, register a handler to detect when a new or
  // updated service worker takes control.
  navigator.serviceWorker.oncontrollerchange = function() {
    console.log('This page is now controlled by:', navigator.serviceWorker.controller);
  };
} else {
  console.log('Service workers are not supported.');
}

• Using Service Workers (en-US)
• Service workers basic code example
• Is ServiceWorker ready?
• Promise
• Using web workers (en-US)