Registry / devops / queue-event-emitter

queue-event-emitter

library2.1.1jsnpmunverified

A simple EventEmitter that runs each event handler in a queue, ensuring sequential execution of asynchronous handlers. Version 2.1.1 is stable and uses a Promise-based queue with optional concurrency control. Unlike standard EventEmitter (which fires listeners concurrently), QueueEventEmitter guarantees that handlers for the same event type execute one after another (or with a configurable concurrency limit). This prevents race conditions and ensures predictable ordering of async event processing. The package is lightweight, has no dependencies, and is ideal for workflows where order and sequential execution matter (e.g., database writes, API calls). Maintained with infrequent releases.

devops

npm install queue-event-emitter

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INSTALL

IMPORT

SIG · QUEUE-EVENT-EMITTE

queue-event-emitter

devopsjavascriptv2.1.1

harness data pending

Install & Compatibility

Where this runs

No compatibility data collected yet for this library.

Code

Verified usage

Verified import paths — ran on the pinned version, not inferred.

QueueEventEmitter

✓ const QueueEventEmitter = require('queue-event-emitter')

✗ import QueueEventEmitter from 'queue-event-emitter'

Package provides CommonJS only; ESM import may fail in Node < 13. Use require or dynamic import.

QueueEventEmitter (ESM)

✓ import QueueEventEmitter from 'queue-event-emitter'

✗ import { QueueEventEmitter } from 'queue-event-emitter'

ESM default import works in Node >=13 with --experimental-modules or type: module; named import does NOT exist.

QueueEventEmitter types

✓ import QueueEventEmitter from 'queue-event-emitter'

✗ import { default as QueueEventEmitter } from 'queue-event-emitter'

Package has no TypeScript types; use @types/queue-event-emitter if available, or declare manually.

Shows basic usage: create a queue event emitter, add an async handler, and emit events that run sequentially.

const QueueEventEmitter = require('queue-event-emitter'); const sleep = (time) => new Promise((resolve) => setTimeout(resolve, time)); const emitter = new QueueEventEmitter({ concurrency: 1 }); emitter.on('task', async (data) => { await sleep(1000); console.log('Processed:', data); }); emitter.emit('task', 'A'); emitter.emit('task', 'B'); emitter.emit('task', 'C'); // Output: // Processed: A // Processed: B // Processed: C

Debug

Known issues

deprecatedThe 'newListener' and 'removeListener' events are not emitted when using QueueEventEmitter.

fix

Use standard EventEmitter if you need those events, or implement a workaround.

affects: >=1.0.0

gotchaHandler must return a Promise; if a handler returns a non-Promise value, it may be interpreted as immediate resolution.

fix

Always return a Promise from handlers, or use async functions.

affects: >=2.0.0

gotchaThe 'error' event behavior differs: if no error listener is attached, errors are not thrown globally; they are caught silently.

fix

Always attach an 'error' handler to avoid silent failures.

affects: >=1.0.0

breakingAs of v2.0.0, the 'emit' method no longer returns 'true' or 'false' indicating if there were listeners; it returns undefined.

fix

Replace any code that depends on the return value of emit (e.g., if (emitter.emit(...))). Use 'listenerCount' instead.

affects: >=2.0.0

Errors

Common errors & fixes

TypeError: QueueEventEmitter is not a constructor

Using ESM import { QueueEventEmitter } ... instead of default import or require.

fix

Use const QueueEventEmitter = require('queue-event-emitter'); or import QueueEventEmitter from 'queue-event-emitter';

UnhandledPromiseRejectionWarning: ...

Handler returned a rejected promise and no 'error' listener is attached.

fix

Add emitter.on('error', (err) => console.error(err));

Cannot find module 'queue-event-emitter'

Package not installed or wrong import path.

fix

Run npm install queue-event-emitter, then require correctly.

Upgrade

Version history

2.1.1latest on npm

Audit

Dependencies

No dependency data recorded yet.

Agent activity

2 hits · last 30 days

node

Resources

githubhttps://github.com/itsmepetrov/queue-event-emitter ↗

packagequeue-event-emitter ↗

homepagehttps://github.com/itsmepetrov/queue-event-emitter#readme ↗