用javascript获取 下拉框 用户选定的文本

<select name='category_id' onChange='selectcate(this)'>

#set ($categorylist = $!{requestmap.getAttribute("categorylist")} )

#foreach($category in $categorylist)

<option value="$category.category_id">$category.title</option>

#end

</select>

<script language="JavaScript">
function selectcate(obj)
{
alert();
val=obj.options[obj.selectedIndex].innerText;
alert(val);
}
</script>