improved.js

var app = require('express')();
var server = require('http').Server(app);
var io = require('socket.io')(server, {path: '/websocket'});
var redis = require('redis');

var redisClient = redis.createClient();
redisClient.subscribe('alerts');
redisClient.on('message', (channel, message_str) => {
    let message = JSON.parse(message_str); // {"to": "foobar", "message": "..."}
    io.to(message.to).emit(message.type, message.data);
});

server.listen(8875);
io.on('connection',  socket => {
     // do something,
});