js 获取下拉框中被选的值

//获取下拉框中被选的值
function GetFile()
{
var objYear=document.getElementById("txtfileurl");
var selfile=objYear.options[objYear.selectedIndex].value;


window.location.href = "http://localhost:88/syspro/service/DownloadData/DownClick.php?txtfileurl=" + selfile;
}