ServiceWorker.state

The state read-only property of the ServiceWorker interface returns a string representing the current state of the service worker. It can be one of the following values: installing, installed, activating, activated, or redundant.

Syntax

someURL = ServiceWorker.state

Value

A String that can take one of the following values:

"installing"

The service worker in this state is considered an installing worker. During this state, ExtendableEvent.waitUntil() can be called inside the install event handler to extend the life of the installing worker until the passed promise resolves successfully. This is primarily used to ensure that the service worker is not active until all of the core caches are populated.

"installed"

The service worker in this state is considered a waiting worker.

"activating"

The service worker in this state is considered an active worker. During this state, ExtendableEvent.waitUntil() can be called inside the onactivate event handler to extend the life of the active worker until the passed promise resolves successfully. No functional events are dispatched until the state becomes activated.

"activated"

The service worker in this state is considered an active worker ready to handle functional events.

"redundant"

A new service worker is replacing the current service worker, or the current service worker is being discarded due to an install failure.

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.

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);
  });
}

Specifications

Browser compatibility

Desktop Mobile
Chrome Edge Firefox Internet Explorer Opera Safari WebView Android Chrome Android Firefox for Android Opera Android Safari on IOS Samsung Internet
state
40
17
44
Extended Support Releases (ESR) before Firefox 78 ESR do not support service workers and the Push API.
No
27
11.1
40
40
44
27
11.3
4.0

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https://developer.mozilla.org/en-US/docs/Web/API/ServiceWorker/state