Registry / serialization / event-emitter-promisify

event-emitter-promisify

library1.1.0jsnpmunverified

event-emitter-promisify is a lightweight JavaScript and TypeScript utility library designed to convert Node.js `EventEmitter` instances into standard Promises. It enables developers to integrate asynchronous `async/await` syntax with traditional event-driven patterns, specifically by resolving a Promise when a success event (defaulting to 'end') is emitted, and rejecting it upon an 'error' event. The library provides a single, focused function, `promisifyEventEmitter`, which simplifies handling the lifecycle of event emitters in a Promise-based workflow. The current stable version is 1.1.0, released in February 2022. While functional and stable, the project exhibits an infrequent release cadence, with no major updates since its initial introduction. Its primary differentiation lies in offering a specialized solution for EventEmitters, distinguishing it from general-purpose promisification utilities like `util.promisify` that target Node.js-style callback functions.

serialization

npm install event-emitter-promisify

github ↗package ↗

INSTALL

IMPORT

SIG · EVENT-EMITTER-PROM

event-emitter-promisify

serializationjavascriptv1.1.0

Install

—

Import

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Disk

—

Pass rate

0/ 6

Env Coverage0 / 6

glibc

18–22

musl

18–22

Install & Compatibility

Where this runs

tested against v? · npm install

Install × environment matrix

Each cell = how many times install + import succeeded across repeated harness runs. Partial = flaky.
glibc = Debian/Ubuntu slim · musl = Alpine Linux

musl

node 18–226 runs

build_error

glibc

node 18–226 runs

build_error

Code

Verified usage

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

promisifyEventEmitter

✓ import { promisifyEventEmitter } from 'event-emitter-promisify'

✗ const promisifyEventEmitter = require('event-emitter-promisify')

This library is primarily designed for ESM environments, although CommonJS `require` might work with transpilation. TypeScript types are included.

promisifyEventEmitter (TypeScript Type)

✓ import type { PromisifyEventEmitter } from 'event-emitter-promisify'

✗ import { PromisifyEventEmitter } from 'event-emitter-promisify'

When importing only the type, use `import type` for better tree-shaking and explicit intent.

Demonstrates how to use `promisifyEventEmitter` with a simple Node.js Readable stream, collecting data and awaiting its completion.

import { promisifyEventEmitter } from 'event-emitter-promisify'; import { Readable } from 'stream'; async function processStream() { const stream = new Readable({ read() { this.push('some data'); this.push(null); // Signal end of stream } }); let receivedData = ''; const promise = promisifyEventEmitter( stream.on('data', (chunk) => { receivedData += chunk.toString(); }) ); try { await promise; console.log('Stream processed successfully. Received:', receivedData); } catch (error) { console.error('Stream encountered an error:', error.message); } } processStream();

Debug

Known issues

breakingThe package was renamed from `@jeswr/promisify-event-emitter` to `event-emitter-promisify` in version 1.1.0. Projects using the older scoped name must update their `package.json` and import paths.

fix

Update `package.json` to depend on `event-emitter-promisify` and change all import statements from `@jeswr/promisify-event-emitter` to `event-emitter-promisify`.

affects: >=1.1.0

gotchaBy default, the promise resolves when the `end` event is emitted. If your `EventEmitter` never emits an `end` event, the promise will never resolve unless an `error` event is emitted or a custom success event is configured.

fix

Ensure your `EventEmitter` pipeline reliably emits an `end` event upon completion, or provide a second argument to `promisifyEventEmitter` to specify a custom event that signifies success and a return value.

affects: >=1.0.0

gotchaThe promise will only reject if the `error` event is emitted by the `EventEmitter`. If an underlying asynchronous operation fails without emitting an `error` event, the promise may hang indefinitely.

fix

Implement robust error handling within your `EventEmitter` producer to ensure that any failure condition results in an `error` event being emitted. Alternatively, introduce a timeout mechanism for the promise if hanging is a concern.

affects: >=1.0.0

Errors

Common errors & fixes

TypeError: stream.on is not a function

You are attempting to use `promisifyEventEmitter` with an object that does not expose an `.on()` method, meaning it's not a valid `EventEmitter` instance.

fix

Ensure the variable passed to `promisifyEventEmitter` is an instance of `EventEmitter` or an object that implements the `on` method (e.g., a `Readable` stream, `net.Socket`, etc.).

Promise never resolves (application hangs)

The `EventEmitter` passed to `promisifyEventEmitter` (or its underlying mechanism) is not emitting the 'end' event (or a custom configured success event) and is also not emitting an 'error' event.

fix

Review the logic of your `EventEmitter` producer to verify that it eventually emits a 'end' event (or your specified custom success event) when its operation completes, or an 'error' event if a failure occurs. Debug the EventEmitter's event flow.

Upgrade

Version history

1.1.0latest on npm

Audit

Dependencies

No dependency data recorded yet.

Agent activity

4 hits · last 30 days

node

Resources

githubhttps://github.com/jeswr/promisify-event-emitter ↗

packagehttps://www.npmjs.com/package/event-emitter-promisify ↗