Websockets can be proxied, but the method is undocumented

Created by: dceddia

If you are reporting a bug, please fill in below. Otherwise feel free to remove this template entirely.

Can you reproduce the problem with latest npm?

Yes

Description

I was trying to proxy Websockets through the "proxy" feature built into CRA. With a proxy setting of "http://localhost:4000" (an express server), the Websocket doesn't work. However, with a URL of "ws://localhost:4000", the Websockets do work! 😄 (along with regular HTTP requests). According to the underlying http-proxy-middleware library, this is supported.

This is great. So why file this issue? There are 2 conflicting pieces of info in CRA:

• This comment in start.js implies Websockets are supported.
• The README / User Guide says "Currently the proxy option only handles HTTP requests, and it won’t proxy WebSocket connections."

I'd be happy to submit a PR with these changes.

Expected behavior

The README should advertise Websocket proxying with the "ws://" prefix, and the comment in start.js should probably be updated to mention the prefix too.

Actual behavior

The current docs about Websockets undersell the actual functionality 😄

Environment

This isn't environment-related.