Reducers

In Redux, reducers are functions in charge of updating the state as new actions happen. They receive the current state and the action (including any payload) and return a new state object. We won't go deep into how reducers work, we just need to understand their basic structure:

/*** src/reducers/index ***/

const initialState = {
  images: null,
  userImages: null,
  error: null,
  user: {
    id: 78261,
    name: 'Sharer1',
    pic: 'https://cdn.pixabay.com/photo/2015/07/20/12/53/
          man-852762_960_720.jpg'
  }
}

export default function (state = initialState, action) {
  switch(action.type){
    case 'FETCH_IMAGES': 
      return Object.assign({}, state, {
        images: [],
        fetchingImages: true,
        error: null
      });
    case 'FETCH_IMAGES_SUCCESS': 
      return Object.assign({}, state, {
        fetchingImages: false,
        images: action.images,
        error: null
      });
    case 'FETCH_IMAGES_ERROR': 
      return Object.assign({}, state, {
...