Connecting NodeJS Express to MS SQL Server

Question

I'm a NodeJS newbie and I am building an application that talks to an MSSQL (SQL Server 2008 R2) Database. For this, I tried using Sequelize, an ORM library that claims to do so.
While I have been successful in making it work with MySQL, SQL Server connection is just not working. I connected to a local database on both the occasions. Here's what I tried (as given in the docs):

[Part 1: Establish Connection]

... Express Code ...
var Sequelize = require('sequelize');

var sequelize = new Sequelize('NewDB', '', '', {
  host: '(localdb)\v11.0',
  dialect: 'mssql',

  pool: {
    max: 5,
    min: 0,
    idle: 10000
  }
});

[Part 2: Testing]

var User = sequelize.define('user', {
  firstName: {
    type: Sequelize.STRING,
    field: 'first_name' // Will result in an attribute that is firstName when user facing but first_name in the database
  },
  lastName: {
    type: Sequelize.STRING
  }
}, {
  freezeTableName: true // Model tableName will be the same as the model name
});

User.sync({force: true}).then(function () {
  // Table created
  return User.create({
    firstName: 'John',
    lastName: 'Hancock'
  });
});

... Express Code ...

The database NewDB does exist on the server. Now, While using SQL Server Express, the same credentials work. But not here. The error that I see is:

Unhandled rejection SequelizeConnectionError: Failed to connect to (localdb)\v11.0:1433 = getaddrinfo ENOTFOUND (localdb)\v11.0

So, here's the question. What credentials do I put, so that it works? And if it doesn't what would be alternate library to establish a Database connection? I'll prefer an ORM, but it's not that important a thing (anything works as long as I can connect to the DB).