Web/API/ServiceWorkerContainer/ready

The ready read-only property of the ServiceWorkerContainer interface 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 active worker. Once that condition is met, it resolves with the ServiceWorkerRegistration.

Syntax

navigator.serviceWorker.ready.then(function(serviceWorkerRegistration) { ... });

Value

A Promise that will never reject, and which may eventually resolve with a ServiceWorkerRegistration.

Example

if ('serviceWorker' in navigator) {
  navigator.serviceWorker.ready
  .then(function(registration) {
    console.log('A service worker is active:', registration.active);

    // At this point, you can call methods that require an active
    // service worker, like registration.pushManager.subscribe()
  });
} else {
  console.log('Service workers are not supported.');
}

Specifications

Specification	Status	Comment
Service WorkersThe definition of 'ServiceWorkerRegistration.ready' 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
`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

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.

ServiceWorkerContainer.ready by Mozilla Contributors is licensed under CC-BY-SA 2.5.