Socket.io-client: Broken IE 11 loading because of wrong "main" value in package.json

You want to:

• [x] report a bug
• [ ] request a feature

Current behaviour

What is actually happening?

Following the official example of using:

import io from 'socket.io-client';

in a JS app results in a broken site in IE 11.

By broken I don't mean the socket-io functionality doesn't work, but that it breaks loading the whole web app's bundle, including error reporting etc. Because no one tests on IE 11 probably no one really noticed this bug.

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

Just add import io from 'socket.io-client' in a web app and test in IE 11.

Expected behaviour

What is expected?

IE 11 should load the bundle

Setup

• OS: Win 10
• browser: IE 11
• socket.io version:

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

The reason this is happening is because the "main" value in package.json specifies the unbundled source code, not the bundled dist folder, thus the source code gets bundled. Probably some bundlers also process the imported modules, but my version of Webpack doesn't, it only processes user's source code.

The solution would be very simple, to specify one of the dist files as the "main" value.

As a workaround I am using this line, which works:

import io from 'socket.io-client/dist/socket.io.slim.js'