javascript groupby map

오오.. 이런 좋은 함수가 생겨나다니!

 

[링크 : https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/groupBy]

[링크 : https://mong-blog.tistory.com/entry/array-object를-그룹화하는-방법reduce-group]