index.js

const { Pool, Client } = require('pg');

const namespaceQuery = `SELECT nspname
FROM   pg_namespace
WHERE  oid = pg_my_temp_schema();`;

const fnQuery = `CREATE OR REPLACE FUNCTION pg_temp.increment(i integer)
 RETURNS integer
 LANGUAGE plpgsql
AS $function$
    BEGIN
      RETURN i + 1;
    END;
$function$`;

async function main() {
	const pool = new Pool()
	const res0 = await pool.query(namespaceQuery);
	console.log(res0);

	const res1 = await pool.query(fnQuery);
	console.log(res1);

	const res2 = await pool.query(namespaceQuery);
	console.log(res2);

	const res3 = await pool.query(`SELECT pg_temp.increment(0)`);
	console.log(res3);

	try {
		await pool.query('SELECT NWO()');
	} catch(err) {

	}

	const res4 = await pool.query(namespaceQuery);
	console.log(res4);

	const res5 = await pool.query(`SELECT pg_temp.increment(0)`);
	console.log(res5);

	await pool.end()
}

main()