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ObserverCallback.handleEvent()

This is an experimental technology
Because this technology's specification has not stabilized, check the compatibility table for usage in various browsers. Also note that the syntax and behavior of an experimental technology is subject to change in future versions of browsers as the specification changes.

The handleEvent() method of the ObserverCallback interface runs when the associated fetch request runs, providing a FetchObserver object to observe the fetch.

You would never run this function yourself, rather it would be run internally as a result of an observe parameter being defined on a fetch request init object.

Syntax

observe(observer);

Parameters

A FetchObserver object.

Return value

Void.

Examples

Again, you would never run this method by yourself. Refer to the FetchObserver page for a valid observer usage example

Specifications

Not part of a specification yet.

Browser compatibility

Feature Chrome Edge Firefox (Gecko) Internet Explorer Opera Safari (WebKit)
Basic support

No support

No support No support[1] No support

No support

No support
Feature Android Android Webview Edge Firefox Mobile (Gecko) IE Phone Opera Mobile Safari Mobile Chrome for Android
Basic support No support No support No support No support[1] No support No support No support No support

[1] Hidden behind a preference in 55+ Nightly. In about:config, you need to create two new boolean prefs — dom.fetchObserver.enabled and dom.fetchController.enabled — and set the values of both to true.

See also

Document Tags and Contributors

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