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   console log  Server is listening on port 8000      But ideally you d want this instead   console log  Server is listening on port     server port     How do I retrieve the port the server is currently listening on without storing the number in a variable prior to calling server listen     I ve seen this done before but I can t find it in the Node documentation  Maybe it s something specific to express

User · Answer

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.

User · Answer

The easier way is just to call app get  url    which gives you the protocol  sub domain  domain  and port

User · Answer

The findandbind npm addresses this for express restify connect  https   github com gyllstromk node-find-and-bind

User · Answer

var express   require  express        var app   express        app set  port   Config port    8881       var server   app listen app get  port    function             console log  Express server listening on port     server address   port                 Express server listening on port 8881

User · Answer

You might be looking for process env PORT  This allows you to dynamically set the listening port using what are called  quot environment variables quot   The Node js code would look like this  const port   process env PORT    3000   app listen port       gt   console log  Listening on port   port            You can even manually set the dynamic variable in the terminal using export PORT 5000  or whatever port you want

User · Answer

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

User · Answer

const express   require  express                                                                                                                               const morgan   require  morgan   const PORT   3000   morgan token  port    req    gt         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

User · Answer

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  amp  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

User · Answer

I was asking myself this question too  then I came Express 4 x guide page to see this sample   var server   app listen 3000  function        console log  Listening on port  d   server address   port

User · Answer

If you re using express  you can get it from the request object   req app settings port      gt  8080 or whatever your app is listening at

User · Answer

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

User · Answer

In case when you need a port at the time of request handling and app is not available  you can use this   request socket localPort

User · Answer

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

User · Answer

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

User · Answer

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

User · Answer

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

User · Answer

req headers host split      1

User · Answer

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

User · Answer

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

[javascript] NodeJS: How to get the server's port?

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