The ExtendableMessageEvent interface of the ServiceWorker API represents the event object of a message event fired on a service worker (when a channel message is received on the ServiceWorkerGlobalScope from another context) — extends the lifetime of such events.
The ImageBitmapFactories mixin interface contains utility methods to create an ImageBitmap. There is no object of this type, but the two interfaces Window, available within the regular browsing scope, and the WorkerGlobalScope interface for workers, implement this interface.
The scope read-only property of the ServiceWorkerRegistration interface returns a unique identifier for a service worker registration. The service worker must be on the same origin as the document that registers the ServiceWorker.
The unregister method of the ServiceWorkerRegistration interface unregisters the service worker registration and returns a Promise. The promise will resolve to false if no registration was found, otherwise it resolves to true irrespective of whether unregistration happened or not (it may not unregister if someone else just called ServiceWorkerContainer.register with the same scope.) The service worker will finish any ongoing operations before it is unregistered.
The WorkerGlobalScope interface of the Web Workers API is an interface representing the scope of any worker. Workers have no browsing context; this scope contains the information usually conveyed by Window objects — in this case event handlers, the console or the associated WorkerNavigator object. Each WorkerGlobalScope has its own event loop.
The ExtendableEvent interface extends the lifetime of the install and activate events dispatched on the global scope as part of the service worker lifecycle. This ensures that any functional events (like FetchEvent) are not dispatched until it upgrades database schemas and deletes the outdated cache entries.
The isReload read-only property of the FetchEvent interface returns true if the event was dispatched by the user attempting to reload the page, and false otherwise. Pressing the refresh button is a reload while clicking a link and pressing the back button is not.