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
# fetch-event-clientid

Browser compatibility

See also