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executionAsyncId - async_hooks - Node documentation
function executionAsyncId

Usage in Deno

import { executionAsyncId } from "node:async_hooks";
executionAsyncId(): number
<div class="alert alert-warning"><div><svg xmlns="http://www.w3.org/2000/svg" width="14" height="14" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"> <path stroke="none" d="M0 0h24v24H0z" fill="none" /> <path d="M12 9v4" /> <path d="M10.363 3.591l-8.106 13.534a1.914 1.914 0 0 0 1.636 2.871h16.214a1.914 1.914 0 0 0 1.636 -2.87l-8.106 -13.536a1.914 1.914 0 0 0 -3.274 0z" /> <path d="M12 16h.01" /> </svg> Deno compatibility</div><div><p> The executionAsyncId implementation is a non-functional stub.</p> </div></div>
import { executionAsyncId } from 'node:async_hooks';
import fs from 'node:fs';

console.log(executionAsyncId());  // 1 - bootstrap
const path = '.';
fs.open(path, 'r', (err, fd) => {
  console.log(executionAsyncId());  // 6 - open()
});

The ID returned from executionAsyncId() is related to execution timing, not causality (which is covered by triggerAsyncId()):

const server = net.createServer((conn) => {
  // Returns the ID of the server, not of the new connection, because the
  // callback runs in the execution scope of the server's MakeCallback().
  async_hooks.executionAsyncId();

}).listen(port, () => {
  // Returns the ID of a TickObject (process.nextTick()) because all
  // callbacks passed to .listen() are wrapped in a nextTick().
  async_hooks.executionAsyncId();
});

Promise contexts may not get precise executionAsyncIds by default. See the section on promise execution tracking.

Return Type

number

The asyncId of the current execution context. Useful to track when something calls.