Immutable Operations

Mutable Operations

Create

case CREATE_WIDGET:
  state.push(action.payload);
  return state;

Update

case UPDATE_WIDGET:
  state.forEach((widget, index) => {
    if (widget[comparator] === action.payload[comparator]) {
      state.splice(index, 1, action.payload);
    }
  });
  return state;

Delete

case DELETE_WIDGET:
  state.forEach((widget, index) => {
    if (widget[comparator] === action.payload[comparator]) {
      state.splice(index, 1);
    }
  });
  return state;

Immutable Counterparts

Create

case CREATE_ITEM:
  return [...state, action.payload];
case CREATE_ITEM:
  return state.concat(action.payload);

The concat() method is used to merge two or more arrays. This method does not change the existing arrays, but instead returns a new array.

Update

case UPDATE_ITEM:
  return state.map(item => {
    return item[comparator] === action.payload[comparator]
      ? Object.assign({}, item, action.payload) : item;
  });

The map() method creates a new array with the results of calling a provided function on every element in this array.

The Object.assign() method is used to copy the values of all enumerable own properties from one or more source objects to a target object. It will return the target object.

Delete

case DELETE_ITEM:
  return state.filter(item => {
    return item[comparator] !== action.payload[comparator];
  });

The filter() method creates a new array with all elements that pass the test implemented by the provided function.