Why use mobx gist 1

gist.js

// in actions.js
// these are action creators
export const  requestResource= (resourceId)=>({
  type: 'REQUEST_RESOURCE',
  resourceId
})
export const requestResourceSuccess = (resourceId,payload)=>({
  type: 'REQUEST_RESOURCE_SUCCESS',
  resourceId,
  payload
})
export const requestResourceFailure = (resourceId,error)=>({
  type: 'REQUEST_RESOURCE_FAILURE',
  resourceId,
  error
})
export const fetchResource = resourceId => dispatch =>{
  dispatch(requestResource(resourceId));
  return fetch(`url/resource/${resourceId}`)
    .then(response=>response.json())
    .then(json=>dispatch(requestResourceSuccess(resourceId,json)))
    .catch(e=>dispatch(requestResourceFailure(resourceId,e)))
}

// in reducers.js
export default (state = {}, action) => {
  switch (action.type) {
    case 'REQUEST_RESOURCE':
        return {
            resources:{
                ...state.resources,
                [action.resourceId]: {loading:true}
            }
        }
    case 'REQUEST_RESOURCE_SUCCESS':
        return {
            resources:{
                ...state.resources,
                [action.resourceId]: {loading:false,resource:action.payload}
            }
        }
    case 'REQUEST_RESOURCE_FAILURE':
        return {
            resources:{
                ...state,
                [action.resourceId]: {loading:false,error:action.error}
            }
        }
    default:
      return state
  }
}