Write back to client
var net = require('net');
net.createServer(socket=>{
socket.write("hello!\n");
socket.pipe(socket); // write every input back to client
}).listen(9000);
=============== OR ===============
var net = require('net');
net.createServer(socket=>{
socket.write("hello!\n");
socket.on('data',function(data){
socket.write(data);
});
}).listen(9000);