nodejs socket.io ws

var io = require('socket.io')(process.env.PORT || 3500);
const fs = require('fs')

console.log('server has started');

io.on('connection', function(socket) {
    console.log('Connection established');

    socket.on('disconnect', function() {
        console.log('Connection closed');
    });

    socket.on('version', function(){
        fs.readFile('./version.dat', (f1_err, f1_data) => {
        if (f1_err)
        {
         console.error(f1_err);
         f1_data = 'ERROR';
        }


        socket.emit('version_response', {con1: f1_data.toString()});
        console.log('Version Requested | Output: ' + f1_data.toString());
        });
    });
});