var a=document.getElemetsByTagName("select")
alert(a[a.length-1].value)
alert(a[a.length-1].text)
alert(a[a.length-1].options.length)
alert(a[a.length-1].options[0].value)
alert(a[a.length-1].options[0].text)
alert(a[a.length-1].value)
alert(a[a.length-1].text)
alert(a[a.length-1].options.length)
alert(a[a.length-1].options[0].value)
alert(a[a.length-1].options[0].text)
var txt = obj.options[obj.selectedIndex].value;
<select id = 'sel'>
<option value = "test1">test11</option>
<option value = "test2">test22</option>
<option value = "test3">test33</option>
</select><script>
function ss()
{
obj = document.getElementById('sel');
alert(obj.options[obj.options.length-1].value);// 弹出最后一项的value值
alert(obj.options[obj.options.length-1].text);// 弹出最后一项的文本值
}
</script>