How can I know if the data was updated in mysql database or an error had occured

I build a web site. my server side is written in node (express). I use connection to mysql database for updating data. The updating is done by calling to stored procedure. the connection is:

connection.query("call update_user(?)",id,
        function(err, results)
        {
            connection.release();
        });
    }
});

I want to know what the result object contains. when I log it:

console.log(result);

I get the output: "[Object object]".

It's not what I want.

so what are the properties of result object?

I don't know what has changed, but suddenly it work! when I log the result, I get:

{ fieldCount: 0,
affectedRows: 1,
insertId: 0,
serverStatus: 2,
warningCount: 0,
message: '',
protocol41: true,
changedRows: 0 }

So I know if the data has changed.