To integrate any database with nodejs you need a driver package or you can call it a npm module which will provide you with basic API to connect with the database and perform interactions . Same is true with mssql database , here we will integrate mssql with nodejs and perform some basic queries on SQL tabels.
We have assumed that we will have a local instance of mssql database server running on local machine . You can refer this document to do the same .
Also make sure you appropriate user created with privileges added as well.