Subprotocols in 4.3.2

[B-R-Bender]

Hello!
Is there a way to specify a list of subprotocols for ws transport while creating a socket?

something like

const socket = io("wss://localhost:3500", { protocols: ["customProtocol"] });

Thank you!

[B-R-Bender]

looks like it's missing in 4.x (at least what I can find from docs) but was present in 3.x here
could you guys shed some light on this?

[B-R-Bender]

Alright, I've got it working, though it's not stated in the docs.
First you need to specify a transport

const socket = io("wss://localhost:3500", {
    transports: ["websocket"],
    protocols: ["custom-protocol"]
});

than on the server side you can get it with

io.on("connection", (socket) => {
  console.log(socket.client.conn.transport.socket.protocol);
});

[darrachequesne]

Hi! You are absolutely right, the option was indeed missing from the documentation.

It should be fixed now: https://socket.io/docs/v4/client-options/#protocols