node:async_hooks

node:async_hooks provides AsyncLocalStorage, AsyncResource, and createHook from Node’s async_hooks.

Example

import { AsyncLocalStorage } from "node:async_hooks";

const storage = new AsyncLocalStorage();
storage.run("request", async () => {
  await null;
  console.log(storage.getStore()); // request
  queueMicrotask(() => console.log(storage.getStore())); // undefined
});

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Differences from Node

AsyncLocalStorage context is lost in queueMicrotask callbacks and node:fs callbacks.
createHook callbacks (init, before, after, destroy) fire for timers, immediates, and Promise continuations.

Reference

Status: Partial · 36 of 45 suite tests pass (80.0%) · since 1.1.0

Exports

Export	Kind	Status	Notes
`async_hooks`	module	Partial	hooks fire for timers/immediates/promises but not yet for TCP/HTTP/TLS native resources
`createHook()`	function	Full	Creates a new AsyncHook instance
`executionAsyncId()`	function	Full	Returns the asyncId of the current execution context
`triggerAsyncId()`	function	Full	Returns the ID of the resource responsible for calling the callback that is currently being executed
`AsyncLocalStorage`	property	Full	The AsyncLocalStorage class
`AsyncResource`	property	Full	The AsyncResource class

Tests: node-api node:async-hooks: 36 pass, 8 fail, 1 error, 3 skipped. Failing: test-async-hooks-destroy-on-gc.js, test-async-hooks-enable-recursive.js, test-async-hooks-fatal-error.js, test-async-hooks-http-parser-destroy.js, test-async-hooks-top-level-clearimmediate.js, test-async-local-storage-http-agent.js, test-async-local-storage-http-multiclients.js, test-async-local-storage-http-parser-leak.js, and 1 more.