Youtube in React: channels reducer for WATCH_DETAILS_SUCCESS

channels.js

function reduceWatchDetails(responses, prevState) {
  const channelResponse = responses.find(response => response.result.kind === CHANNEL_LIST_RESPONSE);
  let channels = {};
  if (channelResponse && channelResponse.result.items) {
    // we know that there will only be one item
    // because we ask for a channel with a specific id
    const channel = channelResponse.result.items[0];
    channels[channel.id] = channel;
  }
  return {
    ...prevState,
    byId: {
      ...prevState.byId,
      ...channels
    }
  };
}

youtube-api-response-types.js

export const CHANNEL_LIST_RESPONSE = 'youtube#channelListResponse';