ScriptManager ServiceReference DropDownExtender

        <asp:ScriptManager ID="ScriptManager1" runat="server">
        <Services>
            <asp:ServiceReference Path="Service.asmx" />
        </Services>
        </asp:ScriptManager>

1<asp:Panel ID="panelS" runat="server" CssClass="dropshow" Style="display: none; visibility: hidden; border:solid 1px #B5C4CC; width:384px;">
2                                                </asp:Panel>
3                                                <ajaxToolkit:DropDownExtender ID="ddd" runat="server" DropDownControlID="panelS"
4                                                    TargetControlID="tbSearch">
5                                                </ajaxToolkit:DropDownExtender>

 1    function setText() 
 2    {
 3        requestSimpleService = Service.HelloWorld(
 4
 5            document.getElementById('ctl00__tbIndex').value,       
 6            
 7            document.getElementById('ctl00_tbSearch').value,       
 8
 9            OnRequestComplete    
10
11            );
12
13        return false;
14    }
15
16    function OnRequestComplete(result) 
17
18    {
19        document.getElementById('ctl00_panelS').innerHTML=result;
20        document.getElementById('ctl00_panelS').style.display="block";
21    }

Code
 1using System;
 2using System.Web;
 3using System.Collections;
 4using System.Web.Services;
 5using System.Web.Services.Protocols;
 6using System.Data.SqlClient;
 7using System.Web.Script.Services;
 8
 9/**//// <summary>
10/// Service 的摘要说明
11/// </summary>
12[WebService(Namespace = "http://tempuri.org/")]
13[WebServiceBinding(ConformsTo = WsiProfiles.BasicProfile1_1)]
14[ScriptService]
15public class Service : System.Web.Services.WebService
16{
17
18    public Service()
19    {
20
21        //如果使用设计的组件，请取消注释以下行 
22        //InitializeComponent(); 
23    }
24
25    [WebMethod]
26    public string HelloWorld(string i, string keyWord)
27    {
28        string type = "";
29        string html = "";
30        string strSql = "select top 10 word from SearchWord where word like '%" + keyWord + "%' ";
31        SqlDataReader dr = SqlHelper.ExecuteReader(SqlHelper.LIVE_CONN_STRING, System.Data.CommandType.Text, strSql);
32        if (keyWord != null && keyWord != String.Empty)
33        {
34            html += "<table onclick='select()' cellpadding='0' cellspacing='0' border='0' class='keyword_item' width='100%'>";
35            while (dr.Read())
36            {
37                html += "<tr style='padding-top:3px;' onmouseover='onMover(this);' onmouseout='onMout(this);'>";
38                html += "<td>";
39                html += dr["word"].ToString();
40                html += "</td>";
41                html += "</tr>";
42            }
43            html += "</table>";
44        }
45        dr.Close();
46        return html;
47    }
48
49}
50
51