for문 in, of

for (       of       ) {}  : 태그를 돎

 

ex)

<div class="number">1</div>
<div class="number">2</div>
<div class="number">3</div>
<div class="number">4</div>
<div class="number">5</div>
<div class="number">6</div>
<div class="number">7</div>
<div class="number">8</div>
<div class="number">9</div>

 

const numbers = document.getElementsByClass("number");

for (let item of numbers) {}

 

 

for (        in       ) {} : 키를 기반으로 반복

 

ex)

const human = {1번:김상호, 2번:이상호, 3번:삼상호};

for (let key in human){}