js 操作 dropdownlist

var DropDownList1 = document.getElementById("DropDownList控件ID"); //获取DropDownList控件的引用

var DropDownList1_Index = DropDownList1.selectedIndex;                 //获取选择项的索引

var DropDownList1_Value = DropDownList1.options[DropDownList1_Index].value;   //获取选择项的值

var DropDownList1_Text = DropDownList1.options[DropDownList1_Index].text;     //获取选择项的文本

 注：textbox不能事先设置visible属性

block与inline两个元素：block元素的特点是,总是在新行上开始,高度,宽度,行高,边距都可以控制(块元素);Inline 元素的特点是,和其他元素在同一行上,不可控制(内嵌元素)

 

var txtddlWeight = document.getElementById("ddlWeight");
            var valddlWeight = txtddlWeight.options[txtddlWeight.selectedIndex].value;
            if (valddlWeight == "0") {
                document.getElementById("TxtWeight").style.display = "none";
            }
            else {
                document.getElementById("TxtWeight").style.display = "inline";
            }

            txtddlWeight.onchange = function () {
                var valddlWeight = txtddlWeight.options[txtddlWeight.selectedIndex].value;
                if (valddlWeight == "0") {
                    document.getElementById("TxtWeight").style.display = "none";
                    document.getElementById("TxtWeight").setAttribute("value", "");
} else { document.getElementById("TxtWeight").style.display = "inline"; }
                    document.getElementById("TxtWeight").setAttribute("value", "1");

 }