A simple event emitter, without any lib dedicated to.

emitter.js

import * as etched from 'https://unpkg.com/@etchedjs/etched@latest/etched.min.js'

const emitter = etched.model({
  set event (value) {
    console.log('event `event` emitted on `emitter` with value', value) 
  }
})

const emitter2 = etched.model(emitter, {
  set event (value) {
    console.log('event `event` emitted on `emitter2` with value', value) 
  }
})

etched.etch(emitter, { event: 123 }) // 'event `event` emitted on `emitter` with value', 123
etched.etch(emitter, { event: 456 }) // 'event `event` emitted on `emitter` with value', 456
etched.etch(emitter, { event: 789 }) // 'event `event` emitted on `emitter` with value', 789

etched.etch(emitter2, { event: 123 })  // 'event `event` emitted on `emitter` with value', 123 AND 'event `event` emitted on `emitter2` with value', 123
etched.etch(emitter2, { event: 456 }) // 'event `event` emitted on `emitter` with value', 456 AND 'event `event` emitted on `emitter2` with value', 456
etched.etch(emitter2, { event: 789 }) // 'event `event` emitted on `emitter` with value', 789 AND 'event `event` emitted on `emitter2` with value', 789