node-mongodb-replset.js

mongodb = require('mongodb');

url = "mongodb://username@password:host1:27017,host2:27017,host3:27017/database";
mongodb.connect(url, function(err, database){
  if(err){
    console.log("Could not connect: " + err);
  }else{
    console.log("Connected to repl set: " + database.serverConfig.replicaSet);
  }
});