Socket.io: The requested module 'socket.io' does not provide an export named 'default' after upgrade to 3.0

[faradaytrs]

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• [ ] request a feature

Current behaviour

What is actually happening?

js import SocketIO from "socket.io"; export const io = SocketIO(server, { pingInterval: 10000, pingTimeout: 5000, });

Then i get an error in console:

js import SocketIO from "socket.io"; ^^^^^^^^ SyntaxError: The requested module 'socket.io' does not provide an export named 'default'

Steps to reproduce (if the current behaviour is a bug)

1. Install socket.io 3.0 and node 15.0.1
2. Enable type: "module" and --es-module-specifier-resolution=node
3. Get error

Note: the best way (and by that we mean the only way) to get a quick answer is to provide a failing test case by forking the following fiddle.

Expected behaviour

Importing and running like before

What is expected?

Setup

• OS: Mac os Catalina
• browser: no browser
• socket.io version: 3.0

Other information (e.g. stacktraces, related issues, suggestions how to fix)

[faradaytrs]

I tried to upgrade but before i started to change settings etc i couldn't even import it from the package, how do i solve that?

[Sjonnie2nd]

Same here with:
import * as socketIo from 'socket.io' io = socketIo(server)
"This expression is not callable"

[Sjonnie2nd]

I got it working with

import {Server, Socket} from 'socket.io'; const io = new Server(server);

But after it: be aware to update the client-side to 3.0.0 too!
https://github.com/socketio/socket.io-client

[darrachequesne]

You're right, this part was missing from the migration guide, sorry for that.

Server:

import { Server } from "socket.io";

const io = new Server(httpServer);

Client:

import io from "socket.io-client";

const socket = io();

// or, more explicit version
import { Manager } from "socket.io-client";

const manager = new Manager("https://example.com");
const socket = manager.socket("/");

[loilo]

This is not only missing in the migration guide, the npm readme describes the old API as well.

[jecsham]

The guides are still outdated and this is the fourth post that talks about typescript and where I finally find the solution :D

[darrachequesne]

The documentation was updated here: https://socket.io/docs/v3/server-initialization/#Syntax