Node.js server.address().address returns ::

Question

If I remember correctly it used to display "localhost" a few days ago. I am not sure what had changed that made server.address().address return double colons (::) instead. I read here that it returns an IPv6 address (::) if it is available but it's disabled on my PC. https://nodejs.org/api/http.html#http_server_listen_port_hostname_backlog_callback

Answer 1

As the docs say,

Begin accepting connections on the specified port and hostname. 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. A port value of zero will assign a random port.

So, the following code would print running at http://:::3456:

var express      = require('express');
var app          = express();
var server = app.listen(3456, function () {
    var host = server.address().address;
    var port = server.address().port;
    console.log('running at http://' + host + ':' + port)
});

But if you add an explicit hostname:

var server = app.listen(3456, "127.0.0.1", function () {

It would print what you want to see: running at http://127.0.0.1:3456

Also you might want to use some IP lib as pointed in this answer

Best regards, Alexander