How to make connection to Postgres via Node.js?

To make connection to Postgres via Node.js, we use the Pool constructor.

For instance, we write

const { Pool } = require("pg");
const config = {
  user: "foo",
  database: "my_db",
  password: "secret",
  host: "localhost",
  port: 5432,
  max: 10,
  idleTimeoutMillis: 30000,
};
const pool = new Pool(config);
pool.on("error", (err, client) => {
  console.error("idle client error", err.message, err.stack);
});
pool.query("SELECT $1::int AS number", ["2"], (err, res) => {
  if (err) {
    return console.error("error running query", err);
  }
  console.log("number:", res.rows[0].number);
});

to call Pool with the connection config.

Then we call query to make a database query.

We get the results from the res parameter in the callback.