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

With latest node.js (v0.3.8-pre): I checked the documentation, inspected the server instance returned by http.createServer(), and read the source code of server.listen()...

Sadly, the port is only stored temporarily as a local variable and ends up as an argument in a call to process.binding('net').bind() which is a native method. I did not look further.

It seems that there is no better way than keeping a reference to the port value that you provided to server.listen().

Answer 2

In express v3.0,

/* No longer valid */
var app = express.createServer();
app.listen();
console.log('Server running on %s', app.address().port);

no longer works! For Express v3.0, you should create an app and a server this way:

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

var app = express();
var server = http.createServer(app);

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

server.listen(3000);
console.log('Express server started on port %s', server.address().port);

I ran in to this issue myself and wanted to document the new syntax. This and other changes in Express v3.0 are visible at https://github.com/visionmedia/express/wiki/Migrating-from-2.x-to-3.x

Answer 3

const express = require('express');                                                                                                                           
const morgan = require('morgan')
const PORT = 3000;

morgan.token('port', (req) => { 
    return req.app.locals.port; 
});

const app = express();
app.locals.port = PORT;
app.use(morgan(':method :url :port'))
app.get('/app', function(req, res) {
    res.send("Hello world from server");
});

app1.listen(PORT);

Answer 4

below a simple http server and how to get the listening port

var http = require("http");
             function onRequest(request, response) {
               console.log("Request received.");
               response.writeHead(200, {"Content-Type": "text/plain"});
               response.write("Hello World");
               response.end();
             }

             var server =http.createServer(onRequest).listen(process.env.PORT, function(){
            console.log('Listening on port '); //Listening on port 8888
        });

then get the server port by using :

console.log('Express server started on port %s', server.address().port);

Answer 5

req.headers.host.split(':')[1]

Answer 6

Express 4.x answer:

Express 4.x (per Tien Do's answer below), now treats app.listen() as an asynchronous operation, so listener.address() will only return data inside of app.listen()'s callback:

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

var listener = app.listen(8888, function(){
    console.log('Listening on port ' + listener.address().port); //Listening on port 8888
});

Express 3 answer:

I think you are looking for this(express specific?):

console.log("Express server listening on port %d", app.address().port)

You might have seen this(bottom line), when you create directory structure from express command:

alfred@alfred-laptop:~/node$ express test4
   create : test4
   create : test4/app.js
   create : test4/public/images
   create : test4/public/javascripts
   create : test4/logs
   create : test4/pids
   create : test4/public/stylesheets
   create : test4/public/stylesheets/style.less
   create : test4/views/partials
   create : test4/views/layout.jade
   create : test4/views/index.jade
   create : test4/test
   create : test4/test/app.test.js
alfred@alfred-laptop:~/node$ cat test4/app.js 

/**
 * Module dependencies.
 */

var express = require('express');

var app = module.exports = express.createServer();

// Configuration

app.configure(function(){
  app.set('views', __dirname + '/views');
  app.use(express.bodyDecoder());
  app.use(express.methodOverride());
  app.use(express.compiler({ src: __dirname + '/public', enable: ['less'] }));
  app.use(app.router);
  app.use(express.staticProvider(__dirname + '/public'));
});

app.configure('development', function(){
  app.use(express.errorHandler({ dumpExceptions: true, showStack: true })); 
});

app.configure('production', function(){
  app.use(express.errorHandler()); 
});

// Routes

app.get('/', function(req, res){
  res.render('index.jade', {
    locals: {
        title: 'Express'
    }
  });
});

// Only listen on $ node app.js

if (!module.parent) {
  app.listen(3000);
  console.log("Express server listening on port %d", app.address().port)
}