Angular 1.X Redux-Factory

factory.js

(function(app) {
  function TodoServiceFactory() {
    var ADD_TODO = 'ADD_TODO';
    var REMOVE_TODO = 'REMOVE_TODO';
    var ID = -1;

    function findIndex(haystack, needle) {
      var isFound = false;
      var index = -1;
      haystack.some(function mapHaystack(data) {
        index += 1;
        isFound = needle(data, index);

        return isFound;
      });

      if (isFound) {
        return index;
      }

      return -1;
    }

    function TodoService() {
      this.ADD_TODO = ADD_TODO;
      this.REMOVE_TODO = REMOVE_TODO;
    }

    TodoService.prototype.addTodo = function addTodoActionCreator(title, description) {
      ID += 1;

      return {
        type: ADD_TODO,
        payload: {
          id: ID,
          title: title,
          description: description
        }
      };
    };

    TodoService.prototype.removeTodo = function removeTodoActionCreator(id) {
      return {
        type: REMOVE_TODO,
        payload: {
        	id: id,
        }
      };
    }

    TodoService.prototype.todosReducer = function todoReducer(state, action) {
      state = state || [];
      action = action || { type: '' };

      switch(action.type) {
        case ADD_TODO:
          return state.concat([{
            id: action.payload.id,
            title: action.payload.title,
            description: action.payload.description,
            createdAt: Date.now()
          }]);
        case REMOVE_TODO:
          var index = findIndex(state, function findTodoIndex(todo) {
            return todo.id === action.payload.id;
          });

          // This removes the element from the array, without mutating the original state.
          return state
          .slice(0, index)
          .concat(state.slice(index + 1, state.length));
        default:
          return state;
      }
    };

    return new TodoService();
  }

  app.factory('TodoService', TodoServiceFactory);
})(myApp);