How to put objects that are taken from the database into a json file?

Question

JavaScript

There is a code that takes data from the database, converts it to json format and puts it in an array, everything would be fine, but when I open the file in which the data was written, I find that the objects simply lie through "," from each other, although I write the whole array to the file. Here is the code for the entry:

function queryDatabase() {
    var i = 0;
    console.log(`Running query to PostgreSQL server: ${config.host}`);

    const query = 'SELECT * FROM \"Stop\"';

    client.query(query)
        .then(res => {
            const rows = res.rows;

            rows.map(row => {//The code is responsible for taking data and putting it in a file
              console.log(`Read: ${JSON.stringify(row)}`);
              kol[i] = `${JSON.stringify(row)}`;
              ++i;
            });
    fs.writeFileSync("data.json", kol);
    console.log(kol);
    process.exit();

    })
.catch(err => {
  console.log(err);
});
}

This is what is saved in the json file

{"NumberStop":26,"NumberBus":9,"AvgCountPassengers":5,"DayOfWeek":1},{"NumberStop":90,"NumberBus":9,"AvgCountPassengers":5,"DayOfWeek":1},{"NumberStop":27,"NumberBus":9,"AvgCountPassengers":5,"DayOfWeek":1}

And I need to parse the file and so that each such line would simply be entered into an array element.

Answer 1

You are overwriting the file use append
fs.appendFileSync("data.json", kol);

Answer 2

Parentheses [] forgot at the beginning and end. Then there will be an array.

[{"NumberStop":26,"NumberBus":9,"AvgCountPassengers":5,"DayOfWeek":1},{"NumberStop":90,"NumberBus":9,"AvgCountPassengers":5,"DayOfWeek":1},{"NumberStop":27,"NumberBus":9,"AvgCountPassengers":5,"DayOfWeek":1}]