FetchEvent: replacesClientId property

Note: This feature is only available in Service Workers.

The replacesClientId read-only property of the FetchEvent interface is the id of the client that is being replaced during a page navigation.

For example, when navigating from page A to page B replacesClientId is the ID of the client associated with page A. It can be an empty string when navigating from about:blank to another page, as about:blank's client will be reused, rather than be replaced.

Additionally, if the fetch isn't a navigation, replacesClientId will be an empty string. This could be used to access/communicate with a client that will imminently be replaced, right before a navigation.


A string.


self.addEventListener("fetch", (event) => {


Service Workers
# fetch-event-replacesClientId

Browser compatibility

BCD tables only load in the browser

See also