Web/API/ServiceWorkerContainer

The ServiceWorkerContainer interface of the Service Worker 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() method used to register service workers, and the ServiceWorkerContainer.controller property used to determine whether or not the current page is actively controlled.

Properties

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

ServiceWorkerContainer.ready 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 associated with the current page has an ServiceWorkerRegistration.active worker. Once that condition is met, it resolves with the ServiceWorkerRegistration.

Events

controllerchange: Occurs when the document's associated ServiceWorkerRegistration acquires a new active worker. Also available via the ServiceWorkerContainer.oncontrollerchange property.
error: Fired whenever an error occurs in the associated service workers. Also available via the ServiceWorkerContainer.onerror property.
message: Occurs when incoming messages are received by the ServiceWorkerContainer object (e.g. via a MessagePort.postMessage() call.) Also available via the ServiceWorkerContainer.onmessage property.

Methods

ServiceWorkerContainer.register(): Creates or updates a ServiceWorkerRegistration for the given scriptURL.
ServiceWorkerContainer.getRegistration(): Gets a ServiceWorkerRegistration object whose scope matches the provided document URL. The method returns a Promise that resolves to a ServiceWorkerRegistration or undefined.
ServiceWorkerContainer.getRegistrations(): Returns all ServiceWorkerRegistration objects associated with a ServiceWorkerContainer in an array. The method returns a Promise that resolves to an array of ServiceWorkerRegistration.
ServiceWorkerContainer.startMessages(): explicitly starts the flow of messages being dispatched from a service worker to pages under its control (e.g. sent via Client.postMessage()). This can be used to react to sent messages earlier, even before that page's content has finished loading.

Examples

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.');
}

Specifications

Specification	Status	Comment
Service WorkersThe definition of 'ServiceWorkerContainer' in that specification.	Working Draft	Initial definition.

Browser compatibility

Update compatibility data on GitHub

	Desktop						Mobile
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet
`ServiceWorkerContainer` Experimental'	Chrome Full support 40	Edge Full support 17 Full support 17 Full support 16 Disabled' Disabled' From version 16: this feature is behind the `Enable service workers` preference.	Firefox Full support 44 Notes' Full support 44 Notes' Notes' Extended Support Releases (ESR) before Firefox 78 ESR do not support service workers and the Push API.	IE No support No	Opera Full support 27	Safari Full support 11.1	WebView Android Full support 40	Chrome Android Full support 40	Firefox Android Full support 44	Opera Android Full support 27	Safari iOS Full support 11.3	Samsung Internet Android Full support 4.0
`controller` Experimental'	Chrome Full support 40	Edge Full support 17 Full support 17 Full support 16 Disabled' Disabled' From version 16: this feature is behind the `Enable service workers` preference.	Firefox Full support 44 Notes' Full support 44 Notes' Notes' Extended Support Releases (ESR) before Firefox 78 ESR do not support service workers and the Push API.	IE No support No	Opera Full support 27	Safari Full support 11.1	WebView Android Full support 40	Chrome Android Full support 40	Firefox Android Full support 44	Opera Android Full support 27	Safari iOS Full support 11.3	Samsung Internet Android Full support 4.0
`getRegistration` Experimental'	Chrome Full support 40	Edge Full support 17 Full support 17 Full support 16 Disabled' Disabled' From version 16: this feature is behind the `Enable service workers` preference.	Firefox Full support 44 Notes' Full support 44 Notes' Notes' Extended Support Releases (ESR) before Firefox 78 ESR do not support service workers and the Push API.	IE No support No	Opera Full support 27	Safari Full support 11.1	WebView Android Full support 40	Chrome Android Full support 40	Firefox Android Full support 44	Opera Android Full support 27	Safari iOS Full support 11.3	Samsung Internet Android Full support 4.0
`getRegistrations` Experimental'	Chrome Full support 45	Edge Full support 17 Full support 17 Full support 16 Disabled' Disabled' From version 16: this feature is behind the `Enable service workers` preference.	Firefox Full support 44 Notes' Full support 44 Notes' Notes' Extended Support Releases (ESR) before Firefox 78 ESR do not support service workers and the Push API.	IE No support No	Opera Full support 27	Safari Full support 11.1	WebView Android Full support 40	Chrome Android Full support 45	Firefox Android Full support 44	Opera Android Full support 27	Safari iOS Full support 11.3	Samsung Internet Android Full support 4.0
`message` event	Chrome Full support 40	Edge Full support 17 Full support 17 Full support 16 Disabled' Disabled' From version 16: this feature is behind the `Enable service workers` preference.	Firefox Full support 44 Notes' Full support 44 Notes' Notes' Extended Support Releases (ESR) before Firefox 78 ESR do not support service workers and the Push API.	IE No support No	Opera Full support 27	Safari Full support 11.1	WebView Android Full support 40	Chrome Android Full support 40	Firefox Android Full support 44	Opera Android Full support 27	Safari iOS Full support 11.3	Samsung Internet Android Full support 4.0
`oncontrollerchange` Experimental'	Chrome Full support 40	Edge Full support 17 Full support 17 Full support 16 Disabled' Disabled' From version 16: this feature is behind the `Enable service workers` preference.	Firefox Full support 44 Notes' Full support 44 Notes' Notes' Extended Support Releases (ESR) before Firefox 78 ESR do not support service workers and the Push API.	IE No support No	Opera Full support 27	Safari Full support 11.1	WebView Android Full support 40	Chrome Android Full support 40	Firefox Android Full support 44	Opera Android Full support 27	Safari iOS Full support 11.3	Samsung Internet Android Full support 4.0
`onerror` Experimental'	Chrome Full support 40	Edge Full support 17 Full support 17 Full support 16 Disabled' Disabled' From version 16: this feature is behind the `Enable service workers` preference.	Firefox Full support 44 Notes' Full support 44 Notes' Notes' Extended Support Releases (ESR) before Firefox 78 ESR do not support service workers and the Push API.	IE No support No	Opera Full support 27	Safari Full support 11.1	WebView Android Full support 40	Chrome Android Full support 40	Firefox Android Full support 44	Opera Android Full support 27	Safari iOS Full support 11.3	Samsung Internet Android Full support 4.0
`onmessage` Experimental'	Chrome Full support 40	Edge Full support 17 Full support 17 Full support 16 Disabled' Disabled' From version 16: this feature is behind the `Enable service workers` preference.	Firefox Full support 44 Notes' Full support 44 Notes' Notes' Extended Support Releases (ESR) before Firefox 78 ESR do not support service workers and the Push API.	IE No support No	Opera Full support 27	Safari Full support 11.1	WebView Android Full support 40	Chrome Android Full support 40	Firefox Android Full support 44	Opera Android Full support 27	Safari iOS Full support 11.3	Samsung Internet Android Full support 4.0
`onmessageerror`	Chrome No support No	Edge No support 17 — 79	Firefox Full support Yes	IE No support No	Opera ?	Safari Full support Yes	WebView Android No support No	Chrome Android No support No	Firefox Android Full support Yes	Opera Android ?	Safari iOS Full support Yes	Samsung Internet Android No support No
`ready` Experimental'	Chrome Full support 40	Edge Full support 17 Full support 17 Full support 16 Disabled' Disabled' From version 16: this feature is behind the `Enable service workers` preference.	Firefox Full support 44 Notes' Full support 44 Notes' Notes' Extended Support Releases (ESR) before Firefox 78 ESR do not support service workers and the Push API.	IE No support No	Opera Full support 27	Safari Full support 11.1	WebView Android Full support 40	Chrome Android Full support 40	Firefox Android Full support 44	Opera Android Full support 27	Safari iOS Full support 11.3	Samsung Internet Android Full support 4.0
`register` Experimental'	Chrome Full support 40	Edge Full support 17 Full support 17 Full support 16 Disabled' Disabled' From version 16: this feature is behind the `Enable service workers` preference.	Firefox Full support 44 Notes' Full support 44 Notes' Notes' Extended Support Releases (ESR) before Firefox 78 ESR do not support service workers and the Push API.	IE No support No	Opera Full support 27	Safari Full support 11.1	WebView Android Full support 40	Chrome Android Full support 40	Firefox Android Full support 44	Opera Android Full support 27	Safari iOS Full support 11.3	Samsung Internet Android Full support 4.0
`startMessages`	Chrome Full support 74	Edge Full support ≤79	Firefox Full support 64	IE No support No	Opera Full support 62	Safari Full support Yes	WebView Android Full support 74	Chrome Android Full support 74	Firefox Android Full support 64	Opera Android Full support 50	Safari iOS Full support Yes	Samsung Internet Android Full support 11.0

Legend

Full support: Full support
No support: No support
Compatibility unknown: Compatibility unknown
Experimental. Expect behavior to change in the future.': Experimental. Expect behavior to change in the future.
See implementation notes.': See implementation notes.
User must explicitly enable this feature.': User must explicitly enable this feature.