Definition
Service Workers Nightly defines FetchEvent
[Exposed=ServiceWorker]
interface FetchEvent : ExtendableEvent {
constructor(DOMString type, FetchEventInit eventInitDict);
[SameObject] readonly attribute Request request;
readonly attribute Promise<any> preloadResponse;
readonly attribute DOMString clientId;
readonly attribute DOMString resultingClientId;
readonly attribute DOMString replacesClientId;
readonly attribute Promise<undefined> handled;
undefined respondWith(Promise<Response> r);
};