MongoDB security, what am I missing?

If you wanted to push something live with Node JS, Mongo DB & Express does this suffice as a secure way to connect to the Mongo DB?

Can someone explain this code from a security perspective?

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Alot of tutorials simply use...

var mongoClient = new MongoClient(new Server('localhost', 27017));

Mongos Documenation includes...

   var MongoClient = require('mongodb').MongoClient;

    // Connect to the db
    MongoClient.connect("mongodb://localhost:27017/exampleDb", function(err, db) {
      if(!err) {
        console.log("We are connected");
      }
    });

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Code is based on Mongo Documentation - http://mongodb.github.io/node-mongodb-native/api-articles/nodekoarticle1.html#getting-that-connection-to-the-database