Node-SQL with node.js and MS integrated Security
Wish I could add this as a comment but don't have enough reputation yet... but what happens when you run this without providing a username/password in the config object?
Windows Authentication happens at the login level so there is no need to provide it at the application level.
Just browsed the documentation and looks like you cannot provide a raw connection string to connect, but to connect you want to build something that looks like this:
var connectionString= 'Server=MyServer;Database=MyDb;Trusted_Connection=Yes;'
The source code of the mssql module is here: https://github.com/patriksimek/node-mssql/blob/master/src/msnodesql.coffee... maybe you can fork and do a pull request that would provide an optional flag whether to use Windows Authentication or not, and that flag would remove the Uid={#{user}};Pwd={#{password}} (as it's unneeded for Windows Authentication) from the CONNECTION_STRING_PORT variable in the module's source code.