<SELECT id="s" οnchange="pageChage()">
<option value="0">0</option>
<option value="1">5</option>
<option value="2">10</option>
<option value="3">15</option>
</SELECT>
<script type="text/javascript">
function pageChage(){
var s = document.getElementById("s");
var value = document.getElementById("s").value;//0,1,2,3
var text = s.options[s.selectedIndex].text;//0,5,0,15
}
</script>