[문제]

Welcome. In this kata, you are asked to square every digit of a number and concatenate them.

For example, if we run 9119 through the function, 811181 will come out, because 92 is 81 and 12 is 1.

Note: The function accepts an integer and returns an integer

(요약) 문자열 각 숫자를 제곱해서 연결한걸 return.

[풀이]

function squareDigits(num){
  let answer = '';
  num = num + '';

  for(let k in num) {
    answer += num[k] * num[k];
  }

  return answer * 1;
}

숫자를 문자열로 바꿔서 반복문 돌림.