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What is a callback function in Node.js, and what is 'callback hell'? What is a Promise in JavaScript, and what are its three possible states? How do you convert a Node.js callback-based function into a Promise-based one manually, without using util.promisify()? What is the difference between Promise.all(), Promise.allSettled(), Promise.race(), and Promise.any()? How does async/await relate to Promises under the hood, and what does 'await' actually do to program execution? What is the difference between running async operations sequentially with multiple awaits versus concurrently with Promise.all()? How do you implement a retry-with-exponential-backoff pattern for a flaky async operation in Node.js? What is util.promisify(), and when would you still need it in modern Node.js? What is the difference between micro tasks and macro tasks in Node.js's event loop, and how does this affect Promise callback ordering? What is an async generator, and how does 'for await...of' let you consume asynchronously produced data?
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What is the purpose of the 'node:timers/promises' module, and how does it simplify working with delays in async code?

Beginner

Answer

node:timers/promises provides promise-returning versions of setTimeout, setImmediate, and setInterval, letting them be used directly with await instead of needing to be manually wrapped in a Promise constructor -- this removes a very common piece of boilerplate that used to appear at the top of countless Node.js files.
const { setTimeout: sleep } = require('node:timers/promises');

async function retryLater() {
  console.log('Waiting 2 seconds...');
  await sleep(2000);
  console.log('Done waiting.');
}
Real-world example A rate-limited API client uses timers/promises' setTimeout directly with await to pause between retries, replacing a small hand-written 'function delay(ms) { return new Promise(resolve => setTimeout(resolve, ms)); }' helper that used to be copy-pasted into nearly every project.

Common follow-ups: How does timers/promises' setInterval as an async iterator differ from the traditional callback-based setInterval?;Can these promise-based timers be cancelled, and if so how?

Async Patterns;Core Node.js Modules
All 15 Async Patterns questions