Web/API/ServiceWorker

The ServiceWorker interface of the Service Worker API provides a reference to a service worker. Multiple browsing contexts (e.g. pages, workers, etc.) can be associated with the same service worker, each through a unique ServiceWorker object.

A ServiceWorker object is available in the ServiceWorkerRegistration.active property, and the ServiceWorkerContainer.controller property — this is a service worker that has been activated and is controlling the page (the service worker has been successfully registered, and the controlled page has been reloaded.)

The ServiceWorker interface is dispatched a set of lifecycle events — install and activate — and functional events including fetch. A ServiceWorker object has an associated ServiceWorker.state, related to its lifecycle.

Properties

The ServiceWorker interface inherits properties from its parent, Worker.

ServiceWorker.scriptURL Read only: Returns the ServiceWorker serialized script URL defined as part of ServiceWorkerRegistration. The URL must be on the same origin as the document that registers the ServiceWorker.
ServiceWorker.state Read only: Returns the state of the service worker. It returns one of the following values: installing, installed, activating, activated, or redundant.

Event handlers

ServiceWorker.onstatechange Read only: An EventListener property called whenever an event of type statechange is fired; it is basically fired anytime the ServiceWorker.state changes.

Methods

The ServiceWorker interface inherits methods from its parent, Worker, with the exception of Worker.terminate — this should not be accessible from service workers.

Examples

This code snippet is from the service worker registration-events sample (live demo). The code listens for any change in the ServiceWorker.state and returns its value.

if ('serviceWorker' in navigator) {
    navigator.serviceWorker.register('service-worker.js', {
        scope: './'
    }).then(function (registration) {
        var serviceWorker;
        if (registration.installing) {
            serviceWorker = registration.installing;
            document.querySelector('#kind').textContent = 'installing';
        } else if (registration.waiting) {
            serviceWorker = registration.waiting;
            document.querySelector('#kind').textContent = 'waiting';
        } else if (registration.active) {
            serviceWorker = registration.active;
            document.querySelector('#kind').textContent = 'active';
        }
        if (serviceWorker) {
            // logState(serviceWorker.state);
            serviceWorker.addEventListener('statechange', function (e) {
                // logState(e.target.state);
            });
        }
    }).catch (function (error) {
        // Something went wrong during registration. The service-worker.js file
        // might be unavailable or contain a syntax error.
    });
} else {
    // The current browser doesn't support service workers.
}

Specifications

Specification	Status	Comment
Service WorkersThe definition of 'ServiceWorker' 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
`ServiceWorker` 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
`onstatechange` 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
`scriptURL` 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
`state` 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

Legend

Full support: Full support
No support: No support
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.