Asynchronous programming

An operation can start now and its result arrive later. While it waits for I/O, Node can handle other events.

import { readFile } from 'node:fs/promises';

async function readConfig() {
  const text = await readFile('config.json', 'utf8');
  return JSON.parse(text);
}

To be precise: await pauses the rest of that function, not the whole process. Marking a function async doesn't move computation to another thread.

Pitfall: a long synchronous loop still blocks the event loop, even inside an async function.