mongodb - Node.js:Typeerror cannot read property 'find' of undefined -

i've been doing research within these couple of days got stuck while trying test codes got web.

var mongoclient = require('mongodb').mongoclient,    format = require('util').format;    mongoclient.connect('mongodb://127.0.0.1:27017/test', function(err, db) {    if (err) {      throw err;    } else {      console.log("successfully connected database");      db.collection('chat', function(err, collection) {              collection.find({}, {            tailable: true,            awaitdata: true,            numberofretries: -1          })          .sort({            $natural: 1          })          .each(function(err, doc) {            console.log(doc);          })      });        }    db.close();  });

and error is: c:\project\node_modules\mongodb\lib\mongo_client.js:406 throw err ^ missing external library/reference because error says "cannot read property 'find' of undefined".

mongodb version: "2.0.31"

you check possible error in first callback, not second one. instead of

db.collection('chat', function(err, collection) {     collection.find({}, {... 

try:

db.collection('chat', function(err, collection) {     if (err) {         throw err;     } else {         collection.find({}, {... 

this won't make code snippet want, let find out error preventing working.