예제
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
</head>
<body>
<form action="register.php">
<input type="text" name="id" placeholder="아이디를 입력" required pattern="[a-zA-Z].+[0-9]">
<input type="email" name="email" placeholder="이메일 입력">
<input type="submit">
</form>
</body>
</html>
