gistfile1.js

var mongoose = require('mongoose'),
      Schema = mongoose.Schema;

mongoose.connect('mongodb://localhost/lol', function(err) {
  if (err) { console.log(err) }
});

var ChatSchema = new Schema({
  name: String
});

mongoose.model('Chat', ChatSchema);

var Chat = mongoose.model('Chat');

var n = new Chat();
n.name = "chat room";
n.save(function(err,room) {
  console.log(room.id);
});
// run the file
$ node test.js
4e3444818cde747f02000001
$

mongoose 1.7.2
Mongo 1.8.1