Make socket.io including dependencies esm compatible

[Artur-]

Is your feature request related to a problem? Please describe.
@web/test-runner only supports ESM imports: modernweb-dev/web#1439. It is currently not possible to use socket.io with that.

Describe the solution you'd like
All dependencies of socket.io-client should be ESM modules. Right now there are problems with at least

• @socket.io/component-emitter
• parseuri
• parseqs
• yeast
• ws (shouldn't be loaded at all as far as I understand)

[Artur-]

In practice you likely need to mock socket.io in most tests which makes this a not that major issue for this use case

[darrachequesne]

That sounds reasonable 👍

Here is the list of the dependencies for the Socket.IO client:

Dependency	Repository	ESM?
@socket.io/component-emitter	https://github.com/socketio/emitter/	✔️ (@socket.io/component-emitter@3.1.0)
backo2	https://github.com/mokesmokes/backo
debug	https://github.com/debug-js/debug
ms	https://github.com/vercel/ms
engine.io-client	https://github.com/socketio/engine.io-client/	✔️
engine.io-parser	https://github.com/socketio/engine.io-parser	✔️
@socket.io/base64-arraybuffer	https://github.com/socketio/base64-arraybuffer	✔️
has-cors	https://github.com/component/has-cors	✔️ (engine.io-client@6.2.0)
parseqs	https://github.com/galkn/querystring	✔️ (engine.io-client@6.2.0)
parseuri	https://github.com/galkn/parseuri	✔️ (engine.io-client@6.2.0)
yeast	https://github.com/unshiftio/yeast	✔️ (engine.io-client@6.2.0)
socket.io-parser	https://github.com/socketio/socket.io-parser	✔️

Both ws and xmlhttprequest-ssl are only needed for Node.js, so I think they can be ignored in that case.

From: https://socket.io/docs/v4/client-installation/#dependency-tree

[Waxolunist]

Actually it would make it simpler for example in conjunction with esbuild or build less execution if they would be esm compatible.

[darrachequesne]

OK, so starting from socket.io-client@4.5.0 we only include ESM compatible dependencies!