CODEWITHSUNDEEP
javascriptnode.jsexpress
KpsLok
KpsLok

Reputation: 903

Expressjs server address host returns nothing

Following the standard ExpressJs hello word example, i get a host of ' : : '.

Why does this happen?

hello word example:

var server = app.listen(3000, function () {
  var host = server.address().address;
  var port = server.address().port;

  console.log('Example app listening at http://%s:%s', host, port);
});

I found a tip that was add 'localhost' after port parameter. It solved when i was looking just my pc, but it wont work over the network. What should i do?

Upvotes: 14

Views: 8041

Answers (3)

Michael Hobbs
Michael Hobbs

Reputation: 1693

This will give you the results you are looking for. You should not need to include 'localhost'

var server = app.listen(3000, function () {
    var port = server.address().port;
    require('dns').lookup(require('os').hostname(), function (err, add, fam) {
        debug('Example app listening at http://%s:%s', add, port);
    })
});

Upvotes: 2

zangw
zangw

Reputation: 48346

For the code

var server = app.listen(3000, function () {

without an address parameter in the listen function, Node will bind it to any address, related to the address 0.0.0.0 of IPV4, and corresponding to :: in IPV6. And this IPv6 unspecified address, 0:0:0:0:0:0:0:0, is reduced to ::,

After running netstat -a

 TCP    [::]:3000              CP-Q10001:0       LISTENING

We know the node server listen on address :: with port 3000.

Refer to http.listen which express.js used in here 

app.listen = function listen() {
  var server = http.createServer(this);
  return server.listen.apply(server, arguments);
};

If the hostname is omitted, the server will accept connections on any IPv6 address (::) when IPv6 is available, or any IPv4 address (0.0.0.0) otherwise.

Upvotes: 11

lsampaio
lsampaio

Reputation: 943

I tried the example and had the same output for hostname '::', I did the following change as a workaround:

 var server = app.listen(3000, 'localhost', function () {
     var host = server.address().address;
     var port = server.address().port;
     console.log('Example app listening at http://%s:%s', host, port);
});

output:

Example app listening at http://127.0.0.1:3000

Upvotes: 10

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