三级无刷新联动(支持IE，Firefox)

aspx:

            <asp:DropDownList ID="ddlconames" runat="server" AppendDataBoundItems="True">
                <asp:ListItem Value="">请选择厂别</asp:ListItem>
                </asp:DropDownList>
                <asp:RequiredFieldValidator ID="RequiredFieldValidator3" runat="server" ControlToValidate="ddlconames"
                    Display="Dynamic" ErrorMessage="请选择厂别"/>
                    
                <asp:DropDownList ID="ddldept" runat="server" Enabled="false">
                <asp:ListItem Value="">请选择部门</asp:ListItem>
                </asp:DropDownList>
                <asp:RequiredFieldValidator ID="RequiredFieldValidator9" runat="server" ControlToValidate="ddldept"
                   Display="Dynamic" ErrorMessage="请选择部门"/>
                   
                <asp:DropDownList ID="ddluserid" runat="server" Enabled="false">
                <asp:ListItem Value="">请选择用户</asp:ListItem>
                </asp:DropDownList>
                        <asp:RequiredFieldValidator ID="RequiredFieldValidator7" runat="server" ControlToValidate="ddluserid"
                   Display="Dynamic" ErrorMessage="请选择用户"/>

Javascript:

<script language="javascript" type="text/javascript"> 
function jb() 
{ 
    var A=null; 
    try 
    { 
        A=new ActiveXObject("Msxml2.XMLHTTP"); 
    } 
    catch(e) 
    { 
        try 
        { 
            A=new ActiveXObject("Microsoft.XMLHTTP"); 
        } 
        catch(oc) 
        { 
            A=null 
        } 
    } 
    if ( !A && typeof XMLHttpRequest != "undefined" ) 
    { 
        A=new XMLHttpRequest() 
    } 
    return A 
} 
function XmlPostTDept(obj) 
{ 
    var svalue = obj; 
    var weburl = "?conameid="+svalue; 
    var xmlhttp = jb(); 
    xmlhttp.open("get",weburl,true); 
    xmlhttp.onreadystatechange=function() 
    { 
        if(xmlhttp.readyState==4)
        { 
            var result = xmlhttp.responseText;
            document.getElementById("ddldept").length = 0; 
            document.getElementById("ddldept").options.add(new Option("请选择部门","")); 
            document.getElementById("ddldept").disabled=false;
            document.getElementById("ddluserid").length = 0;
            document.getElementById("ddluserid").options.add(new Option("请选择用户",""));
            document.getElementById("ddluserid").disabled=true;  
           if(result!="")
           { 
                var allArray = result.split(","); 
                for(var i=0;i<allArray.length;i++) 
                { 
                    var thisArray = allArray[i].split(";"); 
                    document.getElementById("ddldept").options.add(new Option(thisArray[1].toString(),thisArray[0].toString())); 
                } 
           } 
     } 
 } 
 xmlhttp.send(null); 
} 
function XmlPostTUser(obj) 
{    
    var obj1=document.getElementById("ddlconames").value;
    var weburluser="test.aspx?deptid="+obj+"&conameid="+obj1+"";
    var xmlhttpuser = jb(); 
    xmlhttpuser.open("get",weburluser,true); 
    xmlhttpuser.onreadystatechange=function() 
    { 
        if(xmlhttpuser.readyState==4)
        { 
            var resultuser = xmlhttpuser.responseText;
            document.getElementById("ddluserid").length = 0; 
            document.getElementById("ddluserid").options.add(new Option("请选择用户","")); 
            document.getElementById("ddluserid").disabled=false;
           if(resultuser!="")
           { 
                var allArray = resultuser.split(","); 
                for(var i=0;i<allArray.length;i++) 
                { 
                    var thisArray = allArray[i].split(";"); 
                    document.getElementById("ddluserid").options.add(new Option(thisArray[1].toString(),thisArray[0].toString())); 
                } 
           } 
     } 
 } 
 xmlhttpuser.send(null); 
}  
</script> 

CS:

            if (!IsPostBack)
            {
                this.ddlconames.Attributes.Add("onchange", "XmlPostTDept(this.value)");
                this.ddldept.Attributes.Add("onchange", "XmlPostTUser(this.value)");
            }
private void DeptBind(string strconid)
        {
            PcManage.BLL.UserInfor uf = new PcManage.BLL.UserInfor();
            DataTable dt = uf.ListConDept(strconid);
            string mystr = "";
            if (dt.Rows.Count != 0)
            {
                for (int i = 0; i < dt.Rows.Count; i++)
                {
                    mystr += "," + dt.Rows[i][0].ToString() + ";" + dt.Rows[i][1].ToString();
                }
                mystr = mystr.Substring(1);
            }
            Response.Write(mystr);
            Response.End();
        }
        private void UserBind(string strconid, string strdeptid)
        {
            PcManage.BLL.UserInfor uf = new PcManage.BLL.UserInfor();
            DataTable dt = uf.ListConDeptUsers(strconid, strdeptid);
            string mystr2 = "";
            if (dt.Rows.Count != 0)
            {
                for (int i = 0; i < dt.Rows.Count; i++)
                {
                    mystr2 += "," + dt.Rows[i][0].ToString() + ";" + dt.Rows[i][1].ToString();
                }
                mystr2 = mystr2.Substring(1);
            }
            Response.Write(mystr2);
            Response.End();
        }

效果图如下:

不过还有点问题，本页中不能进行多参数传递，搞得好郁闷，等解决了这个问题在更新。