FetchEvent: clientId property

Baseline Widely available

This feature is well established and works across many devices and browser versions. It’s been available across browsers since April 2018.

Note: This feature is only available in Service Workers.

The clientId read-only property of the FetchEvent interface 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.

Value

A string that represents the client ID.

Examples

js
self.addEventListener("fetch", (event) => {
  console.log(event.clientId);
});

Specifications

Specification
Service Workers Nightly
# fetch-event-clientid

Browser compatibility

desktop mobile
Chrome
Edge
Firefox
Opera
Safari
Chrome Android
Firefox for Android
Opera Android
Safari on iOS
Samsung Internet
WebView Android
WebView on iOS
clientId
Chrome – Full support
Chrome 49 (Release date: 2016-03-02)
footnote Full support
Edge – Full support
Edge 17 (Release date: 2018-04-30)
footnote Full support
Firefox – Full support
Firefox 45 (Release date: 2016-03-08)
footnote Full support
Opera – Full support
Opera 36 (Release date: 2016-03-15)
footnote Full support
Safari – Full support
Safari 11.1 (Release date: 2018-04-12)
footnote Full support
Chrome Android – Full support
Chrome Android 49 (Release date: 2016-03-09)
footnote Full support
Firefox for Android – Full support
Firefox for Android 45 (Release date: 2016-03-08)
footnote Full support
Opera Android – Full support
Opera Android 36 (Release date: 2016-03-31)
footnote Full support
Safari on iOS – Full support
Safari on iOS 11.3 (Release date: 2018-03-29)
footnote Full support
Samsung Internet – Full support
Samsung Internet 5 (Release date: 2016-12-15)
footnote Full support
WebView Android – Full support
WebView Android 49 (Release date: 2016-03-09)
footnote Full support
WebView on iOS – No support
WebView on iOS
footnote No support

Legend

Tip: you can click/tap on a cell for more information.

Full support
Full support
No support
No support

See also