code: function reducer(props, map, key) {
    return Object.assign({}, map, {
      [key]: props[key],
    });
  }
docs: Merge props into a new map
  @param  {Object} props The original prop map
  @param  {Object} map   The new prop map to fill
  @param  {string} key   Each key name that have passed the filter
  @return {Object}       The new prop map with the setted prop