package webextension_polyfill.webrequest; /** Fired when HTTP response headers of a request have been received. **/ typedef OnHeadersReceivedEvent = { /** Registers an event listener callback to an event. **/ function addListener(callback:(details:OnHeadersReceivedDetailsType) -> ts.AnyOf3>, filter:RequestFilter, ?extraInfoSpec:Array):Void; /** Deregisters an event listener callback from an event. **/ function removeListener(callback:(details:OnHeadersReceivedDetailsType) -> ts.AnyOf3>):Void; function hasListener(callback:(details:OnHeadersReceivedDetailsType) -> ts.AnyOf3>):Bool; function hasListeners():Bool; };