ServiceWorkerGlobalScope#serviceWorker to get a service worker object corresponding to a worker itself

Category: Service Worker
Type: New or changed feature
Status: Enabled by default (Chrome 79)
Intent stage: Prepare to ship

Summary

This allows a service worker to get its ServiceWorker object with self.serviceWorker in a service worker script and its current state with self.serviceWorker.state in the script.

Motivation

A service worker instance currently has no way to get its current lifecycle state. There's a bit of a hack one can do where you keep track of the current event as a global variable but that's error prone and doesn't capture the waiting periods correctly. The best way to solve this would be to just allow a service worker to get its ServiceWorker object in a service worker script.

Standards & signals

Specification: https://w3c.github.io/ServiceWorker/#service-worker-global-scope-serviceworker
Firefox: Positive
Safari: Positive
Web developers: Positive
Tracking bug: https://bugs.chromium.org/p/chromium/issues/detail?id=977496

Docs: https://github.com/w3c/ServiceWorker/issues/1077

Samples: https://github.com/web-platform-tests/wpt/blob/master/service-workers/service-worker/global-serviceworker.https.any.js

Explainers: https://github.com/w3c/ServiceWorker/issues/1077

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