state machine using reducer

statemachine.js

const reducer = (state, action) => {
  if (state.status === 'idle') {
    if (action.type === 'fetch') {
      return {
        status: 'fetching'
      }
    }
  }
  if (state.status === 'fetching') {
    if (action.type === 'resolve') {
      return {
        status: 'success'
      }
    }
    if (action.type === 'error') {
      return {
        status: 'failed'
      }
    }
  }
}