PgListenNotify.ts

import createSubscriber from 'pg-listen';

// Function to sleep in between latency samples.
async function sleep(): Promise<void> {
    const delay: number = 1000;
    await new Promise(resolve => setTimeout(resolve, delay));
}

const subscriber = createSubscriber({ connectionString: 'http://postgres:password@localhost:5432' });

subscriber.notifications.on('my-channel', payload => {
    console.log(`Received ${JSON.stringify(payload)}. Latency was ${Date.now() - payload.timestamp} ms`);
});

subscriber.events.on('error', error => {
    console.error(`Fatal database connection error: ${error}`);
    process.exit(1);
});

process.on('exit', () => { subscriber.close(); });

(async (): Promise<void> => {
    await subscriber.connect();
    await subscriber.listenTo('my-channel');
    while (true) {
        await subscriber.notify('my-channel', { timestamp: Date.now() });
        await sleep();
    }
})().catch(e => console.log(e));