Executing javascript code with node.js

I'm trying to execute a javascript code with node.js, and I get always two errors saying :

.port 1 is not active

.port 2 is not active

This my javascript code :

var http = require('http');http.createServer(function (req, res) {    res.writeHead(200, {'Content-Type': 'text/plain'});    res.end('Hello World\n');}).listen(8124, "127.0.0.1");console.log('Server running at http://127.0.0.1:8124/');

Any ideas ?