closeOnBeforeunload not working properly after upgrading to socketio v4.7.5

[sarmad36]

With following configuration
this.socket = io({
closeOnBeforeunload: false,
reconnection: true,
reconnectionDelay: 100,
reconnectionDelayMax: 2000,
reconnectionAttempts: Infinity,
transports: ["polling"],
secure: true,
rejectUnauthorized: false,
forceNew: false,
timeout: 6000,
})

when I try to leave the page on Firefox the socket connection is disconnected and if I try to log the reason for disconnection it says " transport error "

[sarmad36]

@darrachequesne can you provide any input here?

[darrachequesne]

Hi! When setting closeOnBeforeunload: false, the Socket instance will indeed emit a disconnect event when the user reloads the page on Firefox.

Reference: https://socket.io/docs/v4/client-options/#closeonbeforeunload

[sarmad36]

But if I set it to true is silently closes the transport and I am unable to emit any event.
Basically what I want to do is that on javascript "beforeUnload" event I want to emit a socket event it works fine on chrome and other browsers but on firefox no event is being fired.

[darrachequesne]

I was not able to reproduce the issue: https://github.com/socketio/socket.io-fiddle/tree/socket.io/discussions/5055

$ node server.js
server listening at http://localhost:3000
connect NyI3hlDYDpKmSbt9AAAB
received 'bye'
disconnect NyI3hlDYDpKmSbt9AAAB due to transport close
connect 38pAi8rwORkfnrbPAAAD
received 'bye'
disconnect 38pAi8rwORkfnrbPAAAD due to transport close
connect jxE3dn1g6Stpb-ZNAAAH

The beforeunload handler:

window.addEventListener("beforeunload", () => {
  console.log("beforeunload");
  socket.emit("bye");
});

Same behavior on Chromium (v123) and Firefox (v127) on Ubuntu 22.04.

Am I missing something?