Как подключить клиента по socket.io?

<script src="/socket.io/socket.io.js"></script>
<script>
        $(function () {
            var socket = io.connect('https://domain.ru/connect/');    
            socket.emit('data', JSON.stringify({"user": "", "index":""}) );
        });
</script>

var express    = require('express'),
    app        = express(),
    server     = require('http').createServer(app),
    io         = require('socket.io')(server),
    log4js     = require('log4js');

var httpPort   = 9081;

var qStatus    = false;

log4js.configure({
// Error
  appenders: { error: { type: 'file', filename: 'socket-error.log' } },
  categories: { default: { appenders: ['error'], level: 'error' } }, 
// Trace
    appenders: { info: { type: 'file', filename: 'socket-info.log' } },
    categories: { default: { appenders: ['info'], level: 'trace' } },
});

const logger = log4js.getLogger('PATH: '+__filename);

const connects = [];

app.set('views', __dirname + '/views')
app.set('view engine', 'pug')
app.use(express.static(__dirname + '/public'))

server.listen(httpPort, function () {
    logger.info('Server listening at port', httpPort); 
});

app.get('/', function (req, res) {
    res.sendFile(__dirname + '/index.html');
});

io.attach(server);

io.on('connection', function(user) {

    user.on('data', function(data){
      ...
    });


    user.on('disconnect', function () {
         ...
     });

    });
});

upstream backend_hosts {
  server XXX.XXX.XX.XX:9081;
}

server {
    server_name domain.ru;

    listen 80 default_server;
    listen [::]:80 default_server ipv6only=on;
    listen 443 ssl;
    root /var/www/TEST;
    access_log /var/log/nginx/access.log;
    error_log /var/log/nginx/error.log;
    index index.php index.html index.hml index.phtml;
    ssl_certificate /etc/nginx/ssl/server.crt;
    ssl_certificate_key /etc/nginx/ssl/server.key;
    location / {
      try_files $uri $uri/ /index.php?q=$uri & $args;
    }
  
    location ~* \.(jpg|jpeg|gif|css|png|js|ico|html)$ {
      access_log off;
      expires max;
    }
  
    location ~ /\.ht {
      deny  all;
    }
  
    location ~ \.php$ {
      fastcgi_index index.php;
      fastcgi_keep_conn on;
      include /etc/nginx/fastcgi_params;
      fastcgi_pass unix:/run/php/php7.1-fpm.sock;
      fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;
    }

    location /connect/ {
      proxy_http_version 1.1;
      proxy_set_header Upgrade $http_upgrade;
      proxy_set_header Connection "upgrade";
      proxy_read_timeout 86400;
      proxy_pass http://backend_hosts;
    }

}