Is it possible to combine React Native with socket.io

Short of a polyfill for the WebSocket API, you can create a native module that makes use of web-sockets and send events to Javascript using eventDispatcher.

On the Javascript side, you would subscribe to these events using DeviceEventEmitter.addListener.

For more information on using native modules, see the react-native doc on the topic

import { io } from 'socket.io-client'
const socket = io(`${SOCKET_URL}:${SOCKET_PORT}`)

Important! SOCKET_URL should be your local IP address, not localhost or 127.0.0.1.

To check your local IP:
Mac / Linux: run ifconfig in terminal
Windows: run ipconfig --all in shell

Should be something like: const socket = io('http://10.0.1.6:3000', {transports: ['websocket']})

Now, if you want to use socket.io in your RN app, you must use this code:

if (!window.location) {
    // App is running in simulator
    window.navigator.userAgent = 'ReactNative';
}

// This must be below your `window.navigator` hack above
const io = require('socket.io-client/socket.io');
const socket = io('http://chat.feathersjs.com', {
  transports: ['websocket'] // you need to explicitly tell it to use websockets
});

socket.on('connect', () => {
  console.log('connected!');
});

Big thanks for Eric Kryski.

For those like me stumbling across this question looking how to integrate socket.io with react native.

Since React Native has supported websockets for a short time now, you can now set up web sockets really easily with Socket.io. All you have to do is the following

1. npm install socket.io-client
2. first import react-native
3. assign window.navigator.userAgent = 'react-native';
4. import socket.io-client/socket.io
5. in your constructor assign this.socket = io('localhost:3001', {jsonp: false});

So in all it should look like this after npm installing socket.io-client:

import React from 'react-native';

// ... [other imports]

import './UserAgent';

import io from 'socket.io-client/socket.io';

export default class App extends Component {
  constructor(props) {
    super(props);
    this.socket = io('localhost:3001', {jsonp: false});
  }

  // now you can use sockets with this.socket.io(...)
  // or any other functionality within socket.io!

  ...
}

and then in 'UserAgent.js':

window.navigator.userAgent = 'react-native';

Note: because ES6 module imports are hoisted, we can't make the userAgent assignment in the same file as the react-native and socket.io imports, hence the separate module.

EDIT:

The above solution should work, but in the case it doesn't try create a separate socketConfig.js file. In there import anything that is needed, including const io = require('socket.io-client/socket.io'); and having window.navigator.userAgent = 'react-native'; BEFORE requiring socket.io-client. Then you can connect your socket there and have all listeners in one place. Then actions or functions can be imported into the config file and execute when a listener receives data.