<script LANGUAGE="javascript">
function whoisselected(){
var a = document.getElementsByName("abc");
for (var i=0; i<a.length; i++){
if (a[i].checked)
alert(i+"选中");
}
}
</script>
<form method="POST" >
<input type="checkbox" name="abc" value="1">1
<input type="checkbox" name="abc" value="2">2
<input type="checkbox" name="abc" value="3">3
<input type="checkbox" name="abc" value="4">4
<input type="button" value="看看选中谁" onclick=javascript:whoisselected();>
</form>