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(6-8 문자): <input type="text" id="id" autofocus>
<input type="button" onclick="checkLength(6, 8)" value="확인">
<script>
function checkLength(min, max) {
let elem = document.getElementById("id");
let s = elem.value;
if (max < s.length || s.length < min) {
alert(min + " 문자와 " + max + " 문자 사이로 입력해주세요!");
elem.focus();
}
}
</script>
</body>
</html>
Java
복사