Empty .to([]) sends to everybody instead of nobody

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#4,645 8 comments 1 reaction 0 assignees View on GitHub

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Assessment

Difficulty
2/5
Estimated time
1-3 hours
Newbie friendliness
45/100
Issue type
Bug
Clarity
Clearly specified
Activity status
Stale
Tech stack
javascript, node.js, typescript
Domain
backend, networking

Research direction

Start with the server example using io.to([]).emit("hello") and trace the broadcast path for an empty target list. Confirm the behavior with connected clients, then verify that an empty array sends to no clients and that the behavior is covered by a regression test.

Written by the indexing model from the issue text.

Description

enhancement

Describe the bug
io.to([]).emit("hello") sends to everybody instead of nobody

To Reproduce

Socket.IO server version: 4.6.1

Server

import { Server } from "socket.io";

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

io.on("connection", () => {
  io.to([]).emit("hello");
});

Socket.IO client version: 4.6.1

Client

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

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

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

Expected behavior
I expect no message to be sent when an empty array is passed to .to().

Platform:

  • OS: macOS 13.2

Additional context
It's easy to work around, but the behavior was unexpected.

Dominant language
TypeScript
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Forks
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Avg merge
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Merged PRs (30d)
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