<script>
function GetSelValue() {
var objSel = document.getElementById("selOp");
//這是獲取值
alert("當前值: " + objSel.value);
//這是獲取文本
alert("當前文本: " + objSel.options(objSel.selectedIndex).text);
}
</script>
<select name="selOp" id="selOp" οnchange="GetSelValue();">
<option selected value="a">a1</option>
<option value="b" >b2</option>
<option value="c" >c3</option>
<option value="d" >d4</option>
<option value="e" >e5</option>
</select>