[Home](./index.md) > [puppeteer](./puppeteer.md) > [Protocol](./puppeteer.protocol.md) > [BackgroundService](./puppeteer.protocol.backgroundservice.md) > [BackgroundServiceEvent](./puppeteer.protocol.backgroundservice.backgroundserviceevent.md) > [serviceWorkerRegistrationId](./puppeteer.protocol.backgroundservice.backgroundserviceevent.serviceworkerregistrationid.md) ## Protocol.BackgroundService.BackgroundServiceEvent.serviceWorkerRegistrationId property The Service Worker ID that initiated the event. Signature: ```typescript serviceWorkerRegistrationId: ServiceWorker.RegistrationID; ```