Type for emitWithAck seems incorrect

[turnerhayes]

The Typsecript annotations for emitWithAck seem to be off. Following the docs, my types are as follows:

export interface ClientToServerEvents {
  "game:join": (args: {
    gameName: GameID;
    color: ColorID;
  }) => void;
  "game:connect": (args: {
    gameName: GameID;
  }) => void;
  "board:place-marble": (args: {
    gameName: GameID;
    position: BoardPosition;
    color: ColorID;
  }) => void;
}

When I call emitWithAck(), it shows an error:

const result = await this.socket.emitWithAck("game:join", {
            gameName,
            color,
        });

Expected 1 arguments, but got 2.

If I add an extra argument to the "game:join" callback type, the error disappears.

The type for emitWithAck is

emitWithAck<Ev extends EventNames<EmitEvents>>(ev: Ev, ...args: AllButLast<EventParams<EmitEvents, Ev>>): Promise<FirstArg<Last<EventParams<EmitEvents, Ev>>>>;

It seems like AllButLast should not be there; it should just take all parameters of the event handler.

[darrachequesne]

For future readers:

One needs to include the callback in the types:

export interface ClientToServerEvents {
  "game:join": (args: {
    gameName: GameID;
    color: ColorID;
  }, callback: (result: string) => void) => void;
}

// result is typed as "string"
const result = await this.socket.emitWithAck("game:join", {
    gameName,
    color,
});

// same for callback-style
this.socket.emit("game:join", {
    gameName,
    color,
}, (result) => {
  // result is typed as "string"
});

Reference: https://socket.io/docs/v4/typescript/

[ZachHaber]

This might make sense to update the client package to have the same EventNamesWithAck type that the server package does to prevent typescript from allowing misusing emitWithAck on the client side.