client.js

ws = new WebSocket('ws://localhost:5000/');
ws.onmessage = function(obj){
  console.log("got", obj["data"]);
};

ws.send("blar");

server.js

var server, ws;

ws = require('ws');

server = new ws.Server({
  port: 5000
});

server.on('connection', function(connection) {
  return connection.on('message', function(msg) {
    return connection.send(msg);
  });
});