index.js
function reducer(props, map, key) {
  return Object.assign({}, map, {
    [key]: props[key],
  });
}
function reducer(props, map, key) {
  return Object.assign({}, map, {
    [key]: props[key],
  });
}
function reducer ( props , map , key ) { return Object . assign ( { } , map , { [ key ] : props [ key ] , } ) ; }
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
Merge props into a new map