Dispatcher

Dispatcher.js

import DispatcherEvent from './DispatcherEvent'

export default class Dispatcher {
  constructor () {
    this.events = {}
  }

  dispatch (eventName, data) {
    const event = this.events[eventName]
    if (event) {
      event.fire(data)
    }
  }

  on (eventName, callback) {
    let event = this.events[eventName]
    if (!event) {
      event = new DispatcherEvent(eventName)
      this.events[eventName] = event
    }
    event.registerCallback(callback)
  }

  off (eventName, callback) {
    const event = this.events[eventName]
    if (event && event.callbacks.indexOf(callback) > -1) {
      event.unregisterCallback(callback)
      if (event.callbacks.length === 0) {
        delete this.events[eventName]
      }
    }
  }
}

DispatcherEvent.js

export default class DispatcherEvent {
  constructor (eventName) {
    this.eventName = eventName
    this.callbacks = []
  }

  registerCallback (callback) {
    this.callbacks.push(callback)
  }

  unregisterCallback (callback) {
    const index = this.callbacks.indexOf(callback)
    if (index > -1) {
      this.callbacks.splice(index, 1)
    }
  }

  fire (data) {
    const callbacks = this.callbacks.slice(0)
    callbacks.forEach((callback) => {
      callback(data)
    })
  }
}