Event listener

Small and easy to use event listener / emitter with strongly-typed functions.

Install

NPM

1npm install @randombytes/event-emitter

Yarn

1yarn add @randombytes/event-emitter

Import

1import { EventEmitter } from '@randombytes/event-emitter'

Usage

1// Prepare events map for emitter.
2import {EventEmitter} from "./emitter";
3
4// Events map type which will be used by EventEmitter to assist 
5// with functions usage.
6type TestEvents = {
7  'case-one': (title: string) => void
8  'case-two': (title: string, subtitle: string) => void
9  'case-three': (title: string, flag: boolean) => void
10}
11
12// Create event emitter instance.
13const emitter = new EventEmitter<TestEvents>()
14
15// Add listener which will be called for each emitted target events.
16const listenerToken = emitter.on('case-two', (title) => {
17  // Handle `case-two` event with passed title.
18})
19
20// Add listener which will be called only once for emitted 
21// target event.
22emitter.once('case-three', (title, flags) => {
23  // Handle `case-three` event with passed title and flags.
24})
25
26// Emit events assisted by IDE for list of expected arguments.
27emitter.emit('case-two', 'Event title')
28emitter.emit('case-three', 'One time event title', true)
29
30// Unregister listener when it will be required
31listenerToken.invalidate()
32
33// or remove all listeners at once.
34emitter.removeAllListeners()