fix: Drop TypeScript DOM lib dependency

src/client.ts

@@ -20,12 +20,28 @@ export type EventConnected = 'connected'; // connected = socket opened + acknowl
 export type EventClosed = 'closed';
 export type Event = EventConnecting | EventConnected | EventClosed;
 
+/**
+ * The argument is actually the `WebSocket`, but to avoid bundling DOM typings
+ * because the client can run in Node env too, you should assert
+ * the websocket type during implementation.
+ */
+export type EventConnectedHandler = (socket: unknown) => void;
+
+export type EventConnectingHandler = () => void;
+
+/**
+ * The argument is actually the websocket `CloseEvent`, but to avoid
+ * bundling DOM typings because the client can run in Node env too,
+ * you should assert the websocket type during implementation.
+ */
+export type EventClosedHandler = (event: unknown) => void;
+
 export type EventListener<E extends Event> = E extends EventConnecting
-  ? () => void
+  ? EventConnectingHandler
   : E extends EventConnected
-  ? (socket: WebSocket) => void
+  ? EventConnectedHandler
   : E extends EventClosed
-  ? (event: CloseEvent) => void
+  ? EventClosedHandler
   : never;
 
 type CancellerRef = { current: (() => void) | null };

src/types.ts

@@ -24,8 +24,13 @@ export interface Disposable {
 export interface Sink<T = unknown> {
   /** Next value arriving. */
   next(value: T): void;
-  /** An error that has occured. Calling this function "closes" the sink. */
-  error(error: Error | CloseEvent | readonly GraphQLError[]): void;
+  /**
+   * An error that has occured. Calling this function "closes" the sink.
+   * The error can be also `CloseEvent`, but to avoid bundling DOM typings
+   * because the client can run in Node env too, you should assert
+   * the close event type during implementation.
+   */
+  error(error: Error | readonly GraphQLError[] | unknown): void;
   /** The sink has completed. This function "closes" the sink. */
   complete(): void;
 }