next.js/examples/with-reflux/store/counterStore.js

import Reflux from 'reflux'
import Actions from '../actions/actions'

export default class StatusStore extends Reflux.Store {
  constructor () {
    super()
    this.state = { counter: 0 }
    this.listenTo(Actions.increment, this.onIncrement)
    this.listenTo(Actions.decrement, this.onDecrement)
  }
  onIncrement () {
    this.setState({ counter: this.state.counter + 1 })
  }
  onDecrement () {
    this.setState({ counter: this.state.counter - 1 })
  }
}