mqemitter

library7.1.0jsnpmunverified

MQEmitter is an opinionated message queue with an emitter-style API using callbacks, designed for Node.js. Current stable version is 7.1.0, requiring Node >=20. It supports topic matching with wildcards (+ and #) and configurable concurrency. Ships TypeScript definitions. Alternatives include Redis, MongoDB, and child-process backends. Good for in-process pub/sub with backpressure handling.

messaging devops

npm install mqemitter

github ↗package ↗homepage ↗

INSTALL

IMPORT

SIG · MQEMITTER

mqemitter

messagingjavascriptv7.1.0

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.

default

✓ import mq from 'mqemitter'

✗ const mq = require('mqemitter')

ESM-only since v7; CommonJS require() is not supported. Use import or dynamic import.

MQEmitter

✓ import { MQEmitter } from 'mqemitter'

✗ import MQEmitter from 'mqemitter'

Named export for class usage; default import is factory function.

MQEmitter type

✓ import type { MQEmitter } from 'mqemitter'

✗ import { MQEmitter } from 'mqemitter'

Use type import for TypeScript type-only usage to avoid runtime overhead.

Shows ESM import, creating an emitter with concurrency limit, subscribing to a topic, emitting a message, and closing the emitter.

import mq from 'mqemitter'; const emitter = mq({ concurrency: 5 }); emitter.on('hello/world', (msg, cb) => { console.log(msg); cb(); }); const message = { topic: 'hello/world', payload: 'data' }; emitter.emit(message, () => { console.log('message emitted'); }); setTimeout(() => emitter.close(() => process.exit(0)), 100);

Debug

Known issues

breakingmqemitter dropped CommonJS support in v7. require() will throw.

fix

Switch to ESM imports (import mq from 'mqemitter') or use dynamic import().

affects: >=7.0.0

breakingMinimum Node.js version increased to 20 in v7.

fix

Upgrade Node.js to version 20 or later.

affects: >=7.0.0

deprecatedCalling mq() without 'new' still works but is deprecated; always use new MQEmitter() or the factory function explicitly.

fix

Use 'new MQEmitter()' or just 'mq()' as factory (both create instance).

affects: >=1.0.0

gotchaListener callback 'done' must never be called with an Error; MQEmitter ignores errors and undefined behavior may occur.

fix

Always call cb() with no argument or null.

affects: >=0.0.0

gotchaemit callback is never called with an error; errors are silently ignored.

fix

Do not rely on error handling in emit callback; validate messages before emitting.

affects: >=0.0.0

Errors

Common errors & fixes

Error [ERR_REQUIRE_ESM]: require() of ES Module /path/node_modules/mqemitter/index.js from /path/app.js not supported.

Using CommonJS require() on an ESM-only package (mqemitter v7+).

fix

Convert your project to ESM or use dynamic import: const mq = await import('mqemitter');

TypeError: mq is not a function

Using default import with TypeScript but without esModuleInterop or proper import.

fix

Ensure you use 'import mq from 'mqemitter'' and have esModuleInterop enabled in tsconfig.json.

TypeError: done is not a function

Inside listener, 'done' is the second argument, but you called it with an argument or misplaced.

fix

Check listener signature: (message, done) => ... and call done() with no error.

Upgrade

Version history

7.1.0latest on npm

Audit

Dependencies

qlobberrequiredtopic matching engine used internally for wildcard subscriptions

Agent activity

5 hits · last 30 days

node

OpenAI (training)

Resources

githubhttps://github.com/mcollina/mqemitter ↗

packagemqemitter ↗

homepagehttps://github.com/mcollina/mqemitter#readme ↗