webpack-bootstrap-ui-kit/src/js/store/reducers/counter.js

export default function counter(state = {
  value: 0,
}, action) {
  switch (action.type) {
    case 'counter/incremented':
      return {
        value: state.value + 1,
      }
    case 'counter/decremented':
      return {
        value: state.value - 1,
      }
    default:
      return state
  }
}