영상
개념
<!DOCTYPE html>
<html lang="ko">
<head>
<meta charset="UTF-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>onclick</title>
</head>
<body>
아이디: <input type="text" id="id" size="10">
<button onclick="checkID()">검사</button>
<script>
function checkID() {
let s = document.getElementById("id").value;
if (s.length < 6) {
alert("아이디는 6글자 이상이어야 합니다.");
}
}
</script>
</body>
</html>
Java
복사