reducers_alt.js

const PUBLICIZE_SHARE = 'PUBLICIZE_SHARE';
const PUBLICIZE_SHARE_SUCCESS = 'PUBLICIZE_SHARE_SUCCESS';
const PUBLICIZE_SHARE_FAILURE = 'PUBLICIZE_SHARE_FAILURE';
const PUBLICIZE_SHARE_DISMISS = 'PUBLICIZE_SHARE_DISMISS';

function update(state, action, post_status){
  var next_state = Object.assign({}, state);
  var post = {};
  post[action.postId] = post_status;
  next_state[action.siteId] = Object.assign({}, next_state[action.siteId], post);
  return next_state;
};

var sharePostStatus = {
  [PUBLICIZE_SHARE] : (state, action)=>update(state, action, {requesting: true}),
  [PUBLICIZE_SHARE_SUCCESS] : (state, action)=>update(state, action, {requesting: false, success: true}),
  [PUBLICIZE_SHARE_FAILURE] : (state, action)=>update(state, action, {requesting: false, success: false, error : action.error}),
  [PUBLICIZE_SHARE_DISMISS] : (state, action)=>update(state, action, undefined)
}