Vue 2 Event Bus, using mitt library

eventBus.js

/**
 * Vue 2 Plugin to add event bus support, using mitt library
 * @see https://github.com/developit/mitt
 *
 * @author Julio Vedovartto <juliovedovatto@gmail.com>
 * @license MIT
 */
import mitt from 'mitt'

const emitter = mitt()

// export emitter instance
export const EventEmitter = {
  ...emitter,
  // inject $on, $off and $emit aliases to the created mitt object
  $on: emitter.on,
  $off: emitter.off,
  $emit: emitter.emit,
  // inject "$once" event handler, since mitt does not support it
  $once(type, handler) {
    const fn = (...args) => {
      this.off(type, fn)
      handler(args)
    }

    this.on(type, fn)
  }
}

/**
 * Add Vue support to use event bus
 * Example: this.$bus.$on / this.$bus.$off / this.$bus.$emit / this.$bus.$once
 *
 * @param {Vue} instance
 */
function install(instance) {
  Object.defineProperty(instance.prototype, '$bus', {
    get() {
      return EventEmitter
    }
  })
}

export default { install }