var dropDownList = document.getElementById("ddl_sheng"); //获取DropDownList控件 var dropDownListValue = dropDownList.options[dropDownList.selectedIndex].value; //获取选择项的值
//**1.设置选中值:(根据索引确定选中值)**// var osel=document.getElementById("selID"); //得到select的ID var opts=osel.getElementsByTagName("option");//得到数组option var obt=document.getElementById("bt"); obt.onclick=function(){ opts[3].selected=tr