This is an experimental technology
Check the Browser compatibility table carefully before using this in production.

The clientId read-only property of the FetchEvent returns the id of the Client that the current service worker is controlling.

The Clients.get() method could then be passed this ID to retrieve the associated client.


var myClientId = FetchEvent.clientId;


A DOMString that represents the client ID.


self.addEventListener('fetch', function(event) {


Specification Status Comment
Service Workers
The definition of 'clientId' in that specification.
Working Draft Initial definition.

Browser compatibility

FeatureChromeEdgeFirefoxInternet ExplorerOperaSafari
Basic support49 ?451 No36 No
FeatureAndroid webviewChrome for AndroidEdge mobileFirefox for AndroidOpera AndroidiOS SafariSamsung Internet
Basic support4949 ?4536 No5.0

1. Service workers (and Push) have been disabled in the Firefox 45 and 52 Extended Support Releases (ESR.)

See also

Document Tags and Contributors

Contributors to this page: fscholz, chrisdavidmills, dgashmdn
Last updated by: fscholz,