inconsistent typing and actual export structure would cause runtime error using with webpack and typescript [v3.0.0]

[noe132]

You want to:

• report a bug
• request a feature

Current behaviour

When using with webpack and typescript,

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

is valid for typescript, but would result an error in runtime.
because when typescript looks for typing, it gets build/index.d.ts,
and webpack try resolve path for the package, and it looks package.json, and found there is field ["exports"]["."]["import"] and use its value ./wrapper.mjs, but has an different export structure than the typing above.

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

Setup a minimal webpack ts-loader build, and using io would get this error message

Expected behaviour

warpper.mjs should have same export structure as build/index.js

Setup

• OS: win10
• browser: chrome 86
• socket.io version: 3.0.0

[Tallyrald]

My problem is probably caused by this so I'll just comment here instead of opening another ticket:
Before v3.0.0 I could do this:

import SocketIO from 'socket.io-client';
let socket = SocketIO.connect('some URL string', { transports: ['websocket'] });

Now I can't. v3.0.1 exposes only 4 properties: protocol, Manager, io, Socket. No methods or subproperties in any of them. Am I missing something? Did the usage pattern change, but it's missing from the changelog?
I'm using Typescript v4.0.5

Edit: Looking at the SocketIO docs I found that the SocketIO export should have a constructor that behaves like the previous connect method, but this is entirely missing from the typings.

[darrachequesne]

@Tallyrald you should be able to use:

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

let socket = io('some URL string', { transports: ['websocket'] });

I think we should have removed the connect() method in v3, as it's just an alias.

@noe132 I could indeed reproduce the issue, as CommonJS and ES module definitions are out of sync.

[Tallyrald]

Oh, you're completely correct, it seems my train of thoughts derailed somewhere between the version upgrade and the seemingly missing exports. Everything is fine, thank you!

[ShaneMcGowan]

Having the same issue. Was starting a new project using socket.io and socket.io-client.

Set Up

OS: win10
browser: chrome 86
socket.io version: 3.0.0

Issue

Webpack is complaining and saying
export 'io' (imported as 'io') was not found in 'socket.io-client'

Work Around

Downgrading to V2.3.1 allowed webpack to bundle everything together and run without issue

[mgroenhoff]

I'm now getting this error when doing import { io } from "socket.io-client"; in my code which is bundled using webpack:

ERROR in ./node_modules/socket.io-client/wrapper.mjs 4:13
Module parse failed: Identifier 'io' has already been declared (4:13)
You may need an appropriate loader to handle this file type, currently no loaders are configured to process this file. See https://webpack.js.org/concepts#loaders
|
| export const Manager = io.Manager;
> export const io = io;
| export default io;
|

[darrachequesne]

This should be fixed in [email protected].

Closed by bec1524.