FetchEvent.replacesClientId

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.

Syntax

var myReplacedClientId = fetchEvent.replacesClientId;

Value

A DOMString.

Example

self.addEventListener('fetch', function(event) {
  console.log(event.replacesClientId);
});

Specifications

Browser compatibility

See also

• Using Service Workers
• Service workers basic code example
• Is ServiceWorker ready?
• Promise
• Using web workers