javascript 怎么获得 服务器控件 dropdownlist的值?

Question

var objDrp = document.getElementById(drp);
objDrp.options[objDrp.selectedIndex].value;

Answer 1

var objDrp = document.getElementById("你的DropDownList的客户端ID"); 
var selectValue;
selectValue  = objDrp.options[objDrp.selectedIndex].value;//Value
selectValue  = objDrp.options[objDrp.selectedIndex].innerText;//Text这样应该可以的

Answer 2

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Text;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;namespace MyUserControl
{
    [DefaultProperty("Text")]
    
    public class WebCustomControl1 : WebControl
    {
        DropDownList dropOne, dropTwo;        [Bindable(true)]
        [Category("Appearance")]
        [DefaultValue("")]
        [Localizable(true)]
        public string Text
        {
            get
            {
                String s = (String)ViewState["Text"];
                return ((s == null) ? String.Empty : s);
            }            set
            {
                ViewState["Text"] = value;
            }
        }        protected override void CreateChildControls()
        {
            dropOne = new DropDownList();            this.Controls.Add(dropOne);            dropTwo = new DropDownList();            this.Controls.Add(dropTwo);      /*      bt = new Button();
            bt.ID = "btaaa";
            bt.OnClientClick = "document.all('TxtCompetence').value = 'xxx'";
            //bt.Attributes.Add("OnClick", "document.all('TxtCompetence').value = 'xxx'");
            this.Controls.Add(bt);*/
        }
        protected override void RenderContents(HtmlTextWriter output)
        {
            ListItem liOne = new ListItem();
            liOne.Text = "是";
            liOne.Value = "y";            ListItem liTwo = new ListItem();
            liTwo.Text = "否";
            liTwo.Value = "n";            ListItem liThree = new ListItem();
            liThree.Text = "-请选择-";
            liThree.Value = "s";            output.AddStyleAttribute(HtmlTextWriterStyle.Position, "absolute");
            output.RenderBeginTag(HtmlTextWriterTag.Table);//1            output.RenderBeginTag(HtmlTextWriterTag.Tr);//2
            output.RenderBeginTag(HtmlTextWriterTag.Td);//3
            output.AddAttribute(HtmlTextWriterAttribute.Type, "Text");
            output.AddAttribute(HtmlTextWriterAttribute.Style, "WIDTH: 100px");
            output.AddAttribute(HtmlTextWriterAttribute.Id, "TxtCompetence");
            output.AddAttribute(HtmlTextWriterAttribute.Value, Text);
            output.RenderBeginTag(HtmlTextWriterTag.Input);//4
            output.RenderEndTag();//4
            output.RenderEndTag();//3            output.RenderBeginTag(HtmlTextWriterTag.Td);//5
            output.AddAttribute(HtmlTextWriterAttribute.Type, "Submit");
            output.AddAttribute(HtmlTextWriterAttribute.Id, "btSubmit");
            //output.AddAttribute(HtmlTextWriterAttribute.
            output.RenderBeginTag(HtmlTextWriterTag.Input);//6
            output.RenderEndTag();//6
            output.RenderEndTag();//5
            output.RenderEndTag();//2            output.RenderBeginTag(HtmlTextWriterTag.Tr);//7
            output.AddAttribute(HtmlTextWriterAttribute.Colspan, "2");
            output.RenderBeginTag(HtmlTextWriterTag.Td);//8
            output.AddAttribute(HtmlTextWriterAttribute.Id, "ValueTable");
            output.RenderBeginTag(HtmlTextWriterTag.Table);//9
            output.RenderBeginTag(HtmlTextWriterTag.Tr);//10
            output.RenderBeginTag(HtmlTextWriterTag.Td);//11
            dropOne.Items.Add(liThree);
            dropOne.Items.Add(liOne);
            dropOne.Items.Add(liTwo);
            dropOne.RenderControl(output);
            output.RenderEndTag();//11            output.RenderBeginTag(HtmlTextWriterTag.Td);//12
            dropTwo.Items.Add(liThree);
            dropTwo.Items.Add(liOne);
            dropTwo.Items.Add(liTwo);
            dropTwo.RenderControl(output);
            output.RenderEndTag();//12            output.RenderBeginTag(HtmlTextWriterTag.Td);//13
            output.AddAttribute(HtmlTextWriterAttribute.Type, "Button");
            output.AddAttribute(HtmlTextWriterAttribute.Id, "btYes");
            output.AddAttribute(HtmlTextWriterAttribute.Value, "确定");
            output.AddAttribute(HtmlTextWriterAttribute.Onclick, "var obj = document.getElementsByTagId('dropOne');docment.all('TxtCompetence').value=obj.options[obj.selectedIndex].value;");
            output.RenderBeginTag(HtmlTextWriterTag.Input);//14
            output.RenderEndTag();//14           // bt.RenderControl(output);            output.AddAttribute(HtmlTextWriterAttribute.Type, "Button");
            output.AddAttribute(HtmlTextWriterAttribute.Id, "baaa");
            output.AddAttribute(HtmlTextWriterAttribute.Value, "...");
            output.AddAttribute(HtmlTextWriterAttribute.Onclick, "document.all('TxtCompetence').value = 'xxx'");
            output.RenderBeginTag(HtmlTextWriterTag.Input);            output.RenderEndTag();
            output.RenderEndTag();//13
            output.RenderEndTag();//10
            output.RenderEndTag();//9
            output.RenderEndTag();//8            output.RenderEndTag();//7
            output.RenderEndTag();//1
        }
    }
}
要做的是  点击 确定(button) 把dropOne(DropDownList)的值给TxtCompetence(TextBox),并显示去出来!