Protocol property of WebSocket object is undefined

[KSDaemon]

My library (Wampy.js) relies on Websocket subprotocols for communication with server.
In RN environment developers faced a problem with initializing ws connection. After a long investigation we found that problem is that after websocket connection is established and onopen callback is fired, protocol property of websocket instance is undefined, but it must contain subprotocol choosen by server.
Analyzing network packets it's clear, that RN client sends Sec-WebSocket-Protocol header, and server responds with approciate Sec-WebSocket-Protocol header value.

React Native version:

info
  React Native Environment Info:
    System:
      OS: macOS 10.14.4
      CPU: (4) x64 Intel(R) Core(TM) i5-4690 CPU @ 3.50GHz
      Memory: 808.31 MB / 24.00 GB
      Shell: 5.7.1 - /usr/local/bin/zsh
    Binaries:
      Node: 11.14.0 - /usr/local/bin/node
      npm: 6.9.0 - /usr/local/bin/npm
    SDKs:
      iOS SDK:
        Platforms: iOS 12.2, macOS 10.14, tvOS 12.2, watchOS 5.2
      Android SDK:
        API Levels: 28
        Build Tools: 28.0.3
    IDEs:
      Android Studio: 3.4 AI-183.5429.30.34.5452501
      Xcode: 10.2.1/10E1001 - /usr/bin/xcodebuild
    npmPackages:
      react: 16.8.3 => 16.8.3
      react-native: 0.59.5 => 0.59.5

Steps To Reproduce

Clone https://github.com/zaytsevfuu/wampytest
yarn install
node node_modules/react-native/local-cli/cli.js run-android
yarn run start
cd crossbar && ./start_wamp.sh

Describe what you expected to happen:
onConnect callback is called

You can find more info in related issue KSDaemon/wampy.js#107

[tegandbiscuits]

I'm also running into this problem using an unrelated library for websockets.

I'm trying use Rails ActionCable with a React Native project, and the client library is failing to work since it checks that protocol property is supported by that version (as of 6.0.0-rc1 of @rails/actioncable).

[cabelitos]

@KSDaemon @NRauh Hey guys I did some diging and I discovered that the procotol was not being set, since the native bridge was not sending the chosen protocol to the websocket object. I created a fix for it and it's ready for review. #25273