io.protocol is undefined

[Anand-Keshavan]

Describe the bug
io.protocol is undefined

To Reproduce

Please fill the following code example:

Socket.IO server version: not relevant

Server

Socket.IO client version: 4.7.5

Client

 import { io } from "socket.io-client";
const revisionNumber = io.protocol;

console.log(`$$$Debug: SocketIo PROTOCOL NUMBER ${revisionNumber}`); --> undefined

Expected behavior
expected the socket protocol number.
As the python-socketio server returns "The client is using an unsupported version of the Socket.IO or Engine.IO protocols"
This is a monrepo with different components using different versions of the socket.io client library.
I need to figure out whether the library used by my component follows the correct protocol.
It is bad enough that there is no way to know the version of the library programmatically.

Platform:

• Device: [e.g. Samsung S8]
• OS: [e.g. Android 9.2]

Additional context
Add any other context about the problem here.

[darrachequesne]

The syntax is:

import { protocol } from "socket.io-client";

console.log(protocol); // current is 5

Reference for the Socket.IO protocol: https://github.com/socketio/socket.io/blob/main/docs/socket.io-protocol/v5-current.md

Same with the underlying Engine.IO client:

import { protocol } from "engine.io-client";

console.log(protocol); // current is 4

Reference for the Engine.IO protocol: https://github.com/socketio/socket.io/blob/main/docs/engine.io-protocol/v4-current.md