Example reducer for request, success, failure pattern

request-success-failure-pattern-reducer.js

const initialState = {
  isLoading: false,
  data: null,
  error: null,
};

const reducer = (state = initialState, action) => {
  switch (action.type) {
    case "GET_DATA_REQUEST":
      return {
        ...state,
        isLoading: true,
        data: null,
        error: null,
      };
    case "GET_DATA_SUCCESS":
      return {
        ...state,
        isLoading: false,
        data: action.data,
        error: null,
      };
    case "GET_DATA_FAILURE":
      return {
        ...state,
        isLoading: false,
        data: null,
        error: action.data,
      };
    default:
      return state;
  }
};