Evmt

Self contained event emitter

Communicate between layers of code without the worry to build a complex solution, thinking of depth, or event injection.

Quick start

Install

npm install --save evmt

Usage

Basic concept

import Evmt from 'evmt'

const onAnimalGoes = new Evmt()
const animalGoes = (animal, sound) => {
  console.log(`${animal} goes ${sound}`)
  onAnimalGoes.emit(animal, sound)
}

// Subscribes to the event
const subscription1 = onAnimalGoes.subscribe((animal) => {
  console.log(`The ${animal} should be quiet!`)
})
const subscription2 = onAnimalGoes.subscribe((animal, sound) => {
  console.log(`I like when the ${animal} goes ${sound}`)
})


animalGoes('Sheep', 'beep') // Emits to both subscribed functions
subscription2.remove()
animalGoes('Cow', 'meow') // Emits to the first subscribed function
subscription1.remove()
animalGoes('Cat', 'Bazinga') // Emits but there is nothing to listen

Advanced usage, with components

import Evmt from 'evmt'

const AnimalListComponent = {
  select(animal) {
    AnimalService.select(animal)
  }
}

const AnimalService = {
  onSelect: new Evmt(),
  select(animal) {
    console.log(`Selected ${animal}`)
    this.onSelect.emit(animal)
  }
}

const FarmComponent = {
  init() {
    this.farmAnimals = []
    this.handleSelectedAnimal = this.handleSelectedAnimal.bind(this)
    this.subscriptions = [
      AnimalService.onSelect.subscribe(this.handleSelectedAnimal)
    ]
  },
  destroy() {
    this.subscriptions.forEach(sub => sub.remove())
  },
  handleSelectedAnimal(animal) {
    this.farmAnimals.push(animal)
    console.log(animal, this.farmAnimals)
  }
}

FarmComponent.init()
AnimalListComponent.select('cow')
AnimalListComponent.select('cat')
AnimalListComponent.select('dog')
FarmComponent.destroy()
AnimalListComponent.select('pig')
AnimalListComponent.select('bat')

---

Documentation

Evmt

It returns it's own instance which is used to subscribe to and emit events.

emit([arg1, ..., argN])

Calls/emits each subscribed callback passing the parameters it received.

Param	Type	Description
arg1...argN	any	A list of values to be emitted

Example

const onSelect = new Evmt()

onSelect.emit(1, '2', { exp: 3 }, [4])

subscribe(callback)

Subscribes an callback into an event to wait for the emit. It returns an "subscription" that can removes itself from the subscriptions.

Param	Type	Description
callback	Function	A function to handle the emitted event

Example

const onSelect = new Evmt()

const subscription = onSelect.subscribe((param1, param2, param3, param4) => {
  console.log(param1, param2, param3, param4)
})

subscription.remove()

remove(index)

Removes the subscribed function from the subscriptions by it's index

Param	Type	Description
index	Number	The subscription index to be removed

Example

const onSelect = new Evmt()

const subscription = onSelect.subscribe((param1, param2, param3, param4) => {
  console.log(param1, param2, param3, param4)
})

// It's the same as subscription.remove()
onSelect.remove(0)