FetchEvent: FetchEvent() constructor

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 FetchEvent() constructor creates a new FetchEvent object.

Syntax

js
new FetchEvent(type, options)

Parameters

type

A string with the name of the event. It is case-sensitive and browsers always set it to fetch.

options

An object that, in addition of the properties defined in ExtendableEvent(), can have the following properties:

request

The Request object that would have triggered the event handler.

preloadResponse

A Promise which returns a previously-loaded response to the client.

clientId Optional

The Client that the current service worker is controlling. It defaults to "".

isReload Optional

A boolean value that signifies whether the page was reloaded or not when the event was dispatched. true if yes, and false if not. Typically, pressing the refresh button in a browser is a reload, while clicking a link and pressing the back button is not. If not present, it defaults to false.

replacesClientId Optional

A string which identifies the client which is being replaced by resultingClientId. It defaults to "".

resultingClientId Optional

A string containing the new clientId if the client changes as a result of the page load. It defaults to ""

handled

A pending promise that will be fulfilled once the event has been handled.

Return value

A new FetchEvent object.

Specifications

Specification
Service Workers
# dom-fetchevent-fetchevent

Browser compatibility

See also