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

request.socket.localPort

Answer 2

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

Answer 3

If you're using express, you can get it from the request object:

req.app.settings.port // => 8080 or whatever your app is listening at.

Answer 4

The easier way is just to call app.get('url'), which gives you the protocol, sub domain, domain, and port.

Answer 5

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

Answer 6

You might be looking for process.env.PORT. This allows you to dynamically set the listening port using what are called "environment variables". The Node.js code would look like this:

const port = process.env.PORT || 3000; 
app.listen(port, () => {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.