Why doesn't socket.io return message on the client?

Question

Socket.io

Come to the server, come back to the client, no

// server
const webpack = require('webpack');
const webpackConfig = require('./webpack.config.js');

const 
    Koa = require('koa'),
    http = require('http'),
    app = new Koa(),
    serve = require('koa-static'),
    server = http.createServer(app.callback()),
    io = require('socket.io')(server);

app.use(serve(__dirname + '/public'));
app.use(require('webpack-hot-middleware')(webpack(webpackConfig)));

io.on('connection', client => {
    client.on('message', req => {
        console.log(req)
        io.to(req.message).emit('message', req.message);
    });
});

server.listen(3000);

// client
import React from 'react';

class Chat extends React.Component {
  constructor(props) {
    super(props);
    this.state = {
      messages: [],
      socket: this.props.socket
    };
  }

  componentDidMount() {
    this.state.socket.emit('message', {message: '123'});

    this.state.socket.on('message', message => {
      console.log(message)
      this.setState({
        messages: [message, ...this.state.messages]
      });
    });
  }
  
  submitMessage = event => {
    if (event.keyCode === 13 && event.target.value !== '') {
      this.state.socket.emit('message', {
        message: event.target.value
      });
      event.target.value = '';
    }
  };

  render() {
    return (<div>
      <ul className="chat__messages">
        {this.state.messages.map((message, index) => (
          <li>
            {message}
          </li>
        ))}
      </ul>
      <input type="text" onKeyUp={this.submitMessage} />
    </div>
    );
  }
}

export default Chat;

Answer 1

Understood it was necessary to transfer to the client

io.on('connection', client => {
    client.on('message', req => {
        console.log(req)
        client.emit('message', req.message);
    });
});