Youtube in React: handling COMMENT_THREAD_SUCCESS action

comments.js

/* ... */
import {COMMENT_THREAD} from '../actions/comment';
/* ... */
export default function (state = initialState, action) {
  switch (action.type) {
    case COMMENT_THREAD[SUCCESS]:
      return reduceCommentThread(action.response, action.videoId, state);
    case WATCH_DETAILS[SUCCESS]:
      return reduceWatchDetails(action.response, action.videoId, state);
    default:
      return state;
  }
}