Example reducer with redux-modifiers

reducer.js

import { handleActions } from 'redux-actions'
import { INVOICE } from '../constants'
import { INVOICE_JSON } from '../data'
import { array, target, update } from 'redux-modifiers'

let obj = {};

let { ADD, UPDATE, REMOVE, RECIPIENT_ADD, ITEM_REMOVE, ITEM_ADD } = INVOICE;

let pl = (value)=>{
  return {payload: value};
}

obj[ADD] = array.add;
obj[UPDATE] = (state, action)=>{
  let { index, selected, value } = action.payload;
  let item = target(...selected, update)(state[index], pl(value));
  return array.updateByIndex(state, pl({ index, item }) );
};
obj[RECIPIENT_ADD] = (state, action)=>{
  let { index } = action.payload;
  let item = target('to', 'recipients', array.add)(state[index], pl(INVOICE_JSON().to.recipients[0]) );
  return array.updateByIndex(state, pl({ index, item }) );
};
obj[ITEM_ADD] = (state, action)=>{
  let { index, selected, value } = action.payload;
  let item = target(...selected, array.add)( state[index], pl(INVOICE_JSON().items[0]) );
  return array.updateByIndex(state, pl({ index, item }) );
};
obj[ITEM_REMOVE] = (state, action)=>{
  let { index, selected } = action.payload;
  let itemIndex = selected.pop();
  let item = target(...selected, array.removeAtIndex)(state[index], pl(itemIndex));
  return array.updateByIndex(state, pl({ index, item }));
};
obj[REMOVE] = array.removeWhere;
export default handleActions(obj, []);