<html>
<head>
<script type="text/javascript">
window.onload = function() {
var sel = document.getElementById("mySelect");
if(sel&&sel.addEventListener){
sel.addEventListener('change',function(e){
var ev = e||window.event;
var target = ev.target||ev.srcElement;
alert(target.value);
},false)
}
}
</script>
</head>
<body>
<form>
Select your favorite fruit:
<select id="mySelect">
<option value="20">Apple</option>
<option value="30">Orange</option>
<option value="40">Pineapple</option>
<option value="50">Banana</option>
</select>
<br /><br />
<input type="button" value="Alert index of selected option">
</form>
</body>
</html>
