Using regex to obtain language from url

app.js

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

app.get(/\/?(\w{2}-\w{2})?\/details/gi, function(req, res) {
 res.send('Hola mundo from:', req.params[0]);
});


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

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