Событие onchange .
jQuery переносит его в помощник .change. Если вы используете простой Javascript, используйте addEventListner('change', function...):
<html>
<head>
<script type="text/javascript" src="jquery-1.2.6.js"></script>
<script type="text/javascript">
// If using jQuery
$(document).ready( function() {
$("#list").attr( "selectedIndex", -1 );
$("#list").change( function() {
$("#answer").text( $("#list option:selected").val() );
});
});
</script>
<script type="text/javascript">
// Plain Javascript:
document.addEventListener('DOMContentLoaded', function(event) {
var selectList = document.getElementById("list");
var divAnswer = document.getElementById("answer");
selectList.addEventListener("change", function(changeEvent) {
divAnswer.textContent = selectList.value;
});
});
</script>
</head>
<body>
<div id="answer">No answer</div>
<form>
Answer
<select id="list">
<option value="Answer A">A</option>
<option value="Answer B">B</option>
<option value="Answer C">C</option>
</select>
</form>
</body>
</html>