NodeJS: How to get the server's port?

Question

You often see example hello world code for Node that creates an Http Server, starts listening on a port, then followed by something along the lines of:

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Answer 1

In the current version (v0.5.0-pre) the port seems to be available as a property on the server object, see http://nodejs.org/docs/v0.4.7/api/net.html#server.address

var server = http.createServer(function(req, res) {
    ...
}

server.listen(8088);
console.log(server.address());
console.log(server.address().address);
console.log(server.address().port);

outputs

{ address: '0.0.0.0', port: 8088 }
0.0.0.0
8088

Answer 2

You can get the port number by using server.address().port like in below code:

var http = require('http');
var serverFunction = function (req, res) {

    if (req.url == '/') {
        console.log('get method');
        res.writeHead(200, { 'content-type': 'text/plain' });
        res.end('Hello World');
    }

}
var server = http.createServer(serverFunction);
server.listen(3002, function () {
    console.log('server is listening on port:', server.address().port);
});

Answer 3

The simplest way to convert from the old style to the new (Express 3.x) style is like this:

var server = app.listen(8080);
console.log('Listening on port: ' + server.address().port);

Pre 3.x it works like this:

/* This no longer works */
app.listen(8080);
console.log('Listening on port: ' + app.address().port);

Answer 4

If you did not define the port number and you want to know on which port it is running.

let http = require('http');
let _http = http.createServer((req, res) => {
res.writeHead(200);
res.end('Hello..!')
}).listen();
console.log(_http.address().port);

FYI, every time it will run in a different port.

Answer 5

Requiring the http module was never necessary.

An additional import of http is not necessary in Express 3 or 4. Assigning the result of listen() is enough.

var server = require('express')();

server.get('/', function(req, res) {
  res.send("Hello Foo!");
});

var listener = server.listen(3000);
console.log('Your friendly Express server, listening on port %s', listener.address().port);
// Your friendly Express server, listening on port 3000

Again, this is tested in Express 3.5.1 & 4.0.0. Importing http was never necessary. The listen method returns an http server object. https://github.com/visionmedia/express/blob/master/lib/application.js#L531

Answer 6

I use this way Express 4:

app.listen(1337, function(){
  console.log('Express listening on port', this.address().port);
});

By using this I don't need to use a separate variable for the listener/server.