heroes.reducer.ts

export function reducer(state = initialState, action: HeroesActions): State {
  switch (action.type) {

    case HeroesActionTypes.FetchHeroes:
      return {
        ...state,
        isLoading: true,
        error: null
      };

    case HeroesActionTypes.FetchHeroesSuccess:
      return {
        ...state,
        isLoading: false,
        data: action.payload.results,
        next: action.payload.next,
        previous: action.payload.previous
      };

    case HeroesActionTypes.FetchHeroesError:
      return {
        ...state,
        isLoading: false,
        error: action.payload
      };

    case HeroesActionTypes.ChangePage:
      return {
        ...state,
        page: action.payload === Pagination.NEXT ? ++state.page : --state.page
      };

    default:
      return state;
  }
}