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ServiceWorkerContainer: ready property

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.

Value

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

Examples

if ("serviceWorker" in navigator) {
  navigator.serviceWorker.ready.then((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.error("Service workers are not supported.");
}

Specifications

Specification
Service Workers # navigator-service-worker-ready

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
`ready`	40	17	44	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/ServiceWorkerContainer/ready