How to define types of the auth properties in socket.io-client

Question

Question

I am using socket.io-client with typescript.

When creating a socket instance, I set a token property in the auth of the Socket options, but an type error occurs when using it.

How can I resolve this?

---

• "socket.io-client": "4.5.0"
• "typescript": "4.6.4"

---

source

import { io, Socket } from "socket.io-client";
import { ServerToClientEventsInterface, ClientToServerEventsInterface } from "../../../backend/socket/interface/socketEventsInterface";
const socket: Socket<ServerToClientEventsInterface, ClientToServerEventsInterface> = io({
    auth: (cb: any) => {
        cb({ token: localStorage.token })
    }
});

socket.on('created', () => {
    console.log("token", socket.auth.token);
});

source capture

error

TS2339: Property 'token' does not exist on type '{ [key: string]: any; } | ((cb: (data: object) => void) => void)'. Property 'token' does not exist on type '(cb: (data: object) => void) => void'.

---

the definition of Socket options

export interface SocketOptions {
    /**
     * the authentication payload sent when connecting to the Namespace
     */
    auth: {
        [key: string]: any;
    } | ((cb: (data: object) => void) => void);
}

---

Reference document

• https://socket.io/docs/v4/client-options/#socket-options
• https://socket.io/docs/v4/middlewares/#sending-credentials

---

tried

I've confirmed that the error can be avoided by the following method, but I don't think it's the right way to go.

socket.on('created', () => {
    const tmp: any = socket.auth;
    console.log("token", tmp.token);
});

---

let me tell you that I can't speak English well. I'm sorry if it's a strange sentence. Please point out any sentences that you do not understand, and I will do my best to correct them.

I would be very grateful if you could answer. Thank you.