Minor: Event handler of 'offline' event must be added on the initial evaluation of worker script on Service Worker

[wanfahmi11]

Describe the bug
Getting a warning when including socket.io client to service worker:

Event handler of 'offline' event must be added on the initial evaluation of worker script on Service Worker

To Reproduce

Socket.IO server version: 4.7.4

Server

import { Server } from "socket.io";

const io = new Server(3000, {});

io.on("connection", (socket) => {
  console.log(`connect ${socket.id}`);

  socket.on("disconnect", () => {
    console.log(`disconnect ${socket.id}`);
  });
});

Socket.IO client version: 4.7.4

Client

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

const socket = io("ws://localhost:3000/", {});

socket.on("connect", () => {
  console.log(`connect ${socket.id}`);
});

socket.on("disconnect", () => {
  console.log("disconnect");
});

Expected behavior
Probably can skip adding "offline" event listener for service worker, since it's already skipped it for offline, I don't see any harm skipping it for service worker.

Platform:

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

Additional context
I would like to contribute myself but I can't find the exact line to modify. I can find the codes in dist/socket.io.js but I'm not sure if that's the right file.

[darrachequesne]

Hi!

The "offline" event listener is added here: https://github.com/socketio/engine.io-client/blob/fa479164251dd1f283dd163143b546582161339a/lib/socket.ts#L397

[FMaz008]

Is there a milestone for this fix? I just installed socket.io (current version being 4.7.5) and I'm encountering this very same warning.

[darrachequesne]

@FMaz008 out of curiosity, could you please explain your use case? Why use a ServiceWorker and not a SharedWorker?

[FMaz008]

@FMaz008 out of curiosity, could you please explain your use case? Why use a ServiceWorker and not a SharedWorker?

Honestly everything works fine with the Service Worker coupled with an Alarm. That and I had never heard of a Shared Worker before today. So it seems I'm just outdated a bit on my knowledge here.

(Not to side track the conversation, but I tried implementing a SharedWorker, but I keep getting a security error. But even assuming I could sort out this problem, it would be a major refactor of the existing code if it worked.)

[darrachequesne]

For future readers:

This should be fixed by 8a2f5a3, included in engine.io-client@6.6.1 and socket.io-client@4.8.0.