Timers as promises in JavaScript

node:timers/promises gives awaitable delays and intervals.

import { setTimeout as delay } from "node:timers/promises";
import { setInterval as every } from "node:timers/promises";

const started = Date.now();
await delay(10);
console.log("waited:", Date.now() - started >= 9);

console.log(await delay(1, "with a value"));

let ticks = 0;
for await (const tick of every(2)) {
  ticks += 1;
  if (ticks === 3) break;
}
console.log("ticks:", ticks);

const controller = new AbortController();
setTimeout(() => controller.abort(), 5);
try {
  await delay(100, null, { signal: controller.signal });
} catch (error) {
  console.log("canceled:", error.name);
}

How it works

1. setTimeout from that module returns a promise.
2. It takes an AbortSignal, so a delay is cancellable.
3. setInterval there is an async iterable.

Keywords and builtins used here

• Date
• as
• await
• break
• catch
• const
• for
• from
• if
• import
• let
• of
• try

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Step 2 of 2 in Events & timers, step 11 of 18 in Node.js.

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