html option的取值问题

<select name="Select1" onchange="slt()">
<option value="1">第一项</option>
<option selected value="2">第二项(默认选中)</option>
<option value="3">第三项</option>
<option value="4">第四项</option>
</select>
<script>
function slt()
{
var obj=document.getElementById("Select1");
alert(obj[obj.selectedIndex].innerText);//这里就是取值
}
</script>

<select name="Select1" onchange="alert(this.options[this.selectedIndex].text)">

<script>
function slt()
{
var obj=document.getElementById("Select1");
alert(obj.options[obj.selectedIndex].text);//这里也是取值
}
</script>