Emitter

A simple and easy to use Emitter library. Focussing on ease of use for TypeScript it supports full autocompletion and type hints for every emission you've configured;

Installation

npm install --save @konfirm/emitter

Usage

The main exported member of the @konfirm/emitter package is Emitter. For Typescript users, the contracts EmitterListenerInterface, EmissionMapper and EmissionInterface are also exported.

export	description
Emitter	The Emitter class, containing al logic to handle (un)registration and emissions
EmitterListenerInterface	TS only interface describing everything but the emit method (as that one probably shouldn't be available outside your code)
EmissionInterface	TS only interface describing the "Emissions" received by the registered handlers
EmissionConfig	TS only type to declare types and their emission structure
EmissionMapper	TS only type to create an EventConfig type from an EmissionInterface implementation class

The Emitter class provides the following methods

method	argument(s)	description
on	type: string, handler: Function	register a handler to receive emissions of type
once	type: string, handler: Function	like on, will unregister itself after receiving once
off	type: string, handler: Function	unregister the handler from receiving emissions of type
emit	emission: EmissionInterface	emit the emission to the handlers listening for the emission type

Javascript

// const { Emitter } = require('@konfirm/emitter'); // CommonJS
import { Emitter } from '@konfirm/emitter'; // ES Module

const emitter = new Emitter();

emitter.on('my-first-emission', (emission: MyFirstEmission) => {
	console.log(emission);
});

emitter.emit({ type: 'my-first-emission' });

Typescript

import { Emitter, Emission } from '@konfirm/emitter';

interface MyFirstEmission extends Emission {
	type: 'my-first-emission' | 'first-emission';
}

interface MySecondEmission extends Emission {
	type: 'my-second-emission' | 'second-emission';
}

type EmissionMap = {
	'my-first-emission': MyFirstEmission;
	'first-emission': MyFirstEmission;
	'my-second-emission': MySecondEmission;
	'second-emission': MySecondEmission;
}

const emitter = new Emitter<EmissionMap>();

emitter.on('my-first-emission', (emission: MyFirstEmission) => {
	console.log(emission);
});

emitter.emit({ type: 'my-first-emission' });

EmissionMapper

The EmissionMapper type can be used to reduce the manual declaration of the EmissionMap provided as type to Emitter. With it the EmissionMap in the example above can be defined using:

import { Emitter, Emission, EmissionMapper } from '@konfirm/emitter';

//...

type EmissionMap = EmissionMapper<'my-first-emission' | 'first-emission', MyFirstEmission> & EmissionMapper<'my-second-emission' | 'second-emission', MySecondEmission>;

const emitter = new Emitter<EmissionMap>();

Or use the template literal types TypeScript introduced with version 4.1.

type EmissionMap = EmissionMapper<`${'my-'|''}first-emission`, MyFirstEmission> & EmissionMapper<`${'my-'|''}second-emission`, MySecondEmission>;

EmissionConfig

While EmissionMapper is

License

MIT License Copyright (c) 2021-2022 Rogier Spieker (Konfirm)

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.