Collection for Redux todo example - This file defines the reducer function

reducers.js

import { types } from './actions';

const initialState = {
  todos: ['Plan web app', 'Analyze use of app', 'Design and develop app', 'Test app', 'Implement and maintain app']
};

export const reducer = (state = initialState, action) => {
  const { todos } = state;
  const { type, payload } = action;

  switch (type) {
    case types.ADDTODO: {
      return {
        ...state,
        todos: [payload, ...todos]
      };
    }
    case types.REMOVETODO: {
      return {
        ...state,
        todos: todos.filter((todo, i) => i !== payload)
      };
    }
  }

  return state;
};