<select id="mySelect">
    <option value="1">Yes</option>
    <option value="2">No</option>
</select>
<input type="button" id="demo" value = "Demo" />
<script type="text/javascript">
    $("#demo").live("click", function () {
        //Get selectedIndex of HTML SELECT based in it's ID
        var selectedIndex = $("#mySelect").attr("selectedIndex");
        alert(selectedIndex);
    });
</script>