0_errorReducer.js

import { checkError } from './actions'

export const checkErrorReducer = makeAsyncReducer(checkError, {
  shouldSpread: true,
  destroyData: false
})

1_using-errorReducer.js

import { checkError } from './actions'
import { checkErrorReducer } from './errorReducer'

const state1 = asyncReducer(undefined, {type: '@@INIT'})
// state1 ⇒ {
//   loading: false
// }

const state2 = asyncReducer(state1, checkError())
// state2 ⇒ {
//   loading: true
// }

const state3 = asyncReducer(state2, checkError.success({ code: 404, message: 'NOT FOUND' }))
// state3 ⇒ {
//   loading: false,
//   code: 404,
//   message: 'NOT FOUND'
// }

// as opposed to the previous example,
// here, data is not deleted on re-launching the process
// because "destroyData" is set to false
const state4 = asyncReducer(state3, checkError())
// state4 ⇒ {
//   loading: true,
//   code: 404,
//   message: 'NOT FOUND'
// }

const state5 = asyncReducer(state4, checkError.error('Fetch Error'))
// state5 ⇒ {
//   loading: false,
//   error: 'Fetch Error'
// }