Once-Emitted

Create a Promise that listens for an event and can resolve or reject based on the event's arguments

Installation

npm install once-emitted

yarn add once-emitted

API

once(emitter, eventName, { timeout, resolveOn, rejectOn });

Creates a promise that listens to emitter for an event with the name eventName. The promise will reject if the timeout (milliseconds) is reached without the event firing or without resolveOn or rejectOn returning true. The once function will pass the emitter listener arguments through to resolveOn and rejectOn.

import { once } from 'once-emitted';
import { EventEmitter } from 'events';

const emitter = new EventEmitter();

const promise = once(emitter, 'statusChange', {
  timeout: 10000,
  resolveOn: (status) => (status === 'initialized'),
  rejectOn: (status) => (['timedOut', 'unauthorized'].includes(status))
});

emitter.emit('statusChange', 'initialized');

const result = await promise;

// { result: ['initialized'] }