The Client interface represents an executable context such as a Worker, or a SharedWorker.
Client
MDN Reference
The frameType read-only property of the Client interface indicates the type of browsing context of the current Client.
frameType
The id read-only property of the Client interface returns the universally unique identifier of the Client object.
id
The type read-only property of the Client interface indicates the type of client the service worker is controlling.
type
The url read-only property of the Client interface returns the URL of the current service worker client.
url
The postMessage() method of the (a Window, Worker, or SharedWorker).
postMessage()