Node.js MSSQL tedius ConnectionError: Failed to connect to localhost:1433 - connect ECONNREFUSED

The solution is to enable TCP connections which are disabled by default.

My case wasn't exactly the same as Matt's, but his screenshot was enough to remember me what was missing.

As it is said here, when you are using the SQL Server Instance Name to connect to it, you must have SQL Server Browser running.

options.instanceName

The instance name to connect to. The SQL Server Browser service must be running on the database server, and UDP port 1434 on the database server must be reachable.

(no default)

Mutually exclusive with options.port.

If after enabling the TCP connection and your configuration is still not working. Here's my own-configuration.

var config = {
    "user": 'admin',
    "password": 'password',
    "server": 'WINDOWS-PC',
    "database": 'database_name',
    "port": 61427, // make sure to change port
    "dialect": "mssql",
    "dialectOptions": {
        "instanceName": "SQLEXPRESS"
    }
};

If somebody still struggles to connect despite doing all that was proposed.
In my case I had to manually set TCP Port property to 1433 in SQL Server Network Configuration -> Protocols for ... -> TCP/IP -> IP Addresses -> IPAll.

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