<select>
<option value="item1">選項1</option>
<option value="item2">選項2</option>
<option value="item3">選項3</option>
</select>

<style>
select {
color: blue;
background-color: gray;
}
</style>

<select size="3">
<option value="item1">選項1</option>
<option value="item2">選項2</option>
<option value="item3">選項3</option>
</select>

<script>
function showItem() {
var index = document.querySelector('select').selectedIndex;
var selectedValue = document.querySelector('select').options[index].value;
window.alert('您選擇的是：' + selectedValue);
}
</script>
<select onchange="showItem()">
<option value="item1">選項1</option>
<option value="item2">選項2</option>
<option value="item3">選項3</option>
</select>