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>
과일선택
<select id="fruits">
<option value="0">선택하세요</option>
<option value="1">사과</option>
<option value="2">배</option>
<option value="3">바나나</option>
</select>
<input type="button" onclick="checkSelection('하나를 선택하여야 합니다.')" value="확인">
<p id="result"></p>
<script>
function checkSelection(msg) {
let elem = document.getElementById("fruits");
if (elem.value == 0) {
alert(msg);
document.querySelector("#result").innerText = msg;
elem.focus();
} else {
document.querySelector("#result").innerText = "선택하신 과일은 " + elem.children[elem.value].innerText + "입니다.";
}
}
</script>
</body>
</html>
Java
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