<body>
        <div id="text"></div>
        <script src="index.js"></script>
    </body>
<style>
            .title {
                color: blue;
                font-size: 25px;
            }
            .title-big {
                font-size: 50px;
            }
        </style>
// HTML 요소 내용 읽고 쓰기
const text = document.getElementById('text');
console.log(text);
text.textContent = 'hi';
text.innerText = '안녕하세요';
text.innerHTML = '여기는 <b>첫번째</b> 태그입니다.';

text.classList.add('title'); //클래스 추가
// text.classList.remove('title'); // css 적용된거 사라짐
text.classList.toggle('title-big');
console.log(text.classList.contains('title-big'));
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External JavaScript

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