JavaScript实现DropDownList(Select)三级联动无刷新

<script language=javascript>
function CountryChange(){
countryid=document.getElementById(“ddlContry”).value;
if(countryid==null||countryid==”"){
alert(“请选择所属国家”);
CountryDel(“ddlProvince”);//清空DropDownList
CountryDel(“ddlCity”);//清空DropDownList
return false;
}
var countrystring=”";
var posturl=location.protocol+”//”+location.hostname+”//soleweb//AjaxEnjine//AreaShow.aspx?AreaId=”+countryid;
countrystring=openUrl(posturl);
if(countrystring==”-2″){//查询失败
alert(“数据查询失败”);
return false;
}
//分割并写入DropDownList

CountryDel(“ddlProvince”);//清空DropDownList
CountryDel(“ddlCity”);//清空DropDownList
if(countrystring==”"){
return false;
}

var stringarray=countrystring.split(“|”);
for(var i=0;i<stringarray.length;i++){//重写DropDownList
//拆分内部数组
var optionarray=stringarray[i].split(“,”);
var newoption=document.createElement(“option”);
newoption.text=optionarray[0];
newoption.value=optionarray[1];
document.getElementById(“ddlProvince”).options.add(newoption);　　
}
}

function CountryDel(AreaName){//清空DropDownList
var countnum=document.getElementById(AreaName).options.length;
for(var i=1;i<countnum;i++){//清空DropDownList
document.getElementById(AreaName).remove(countnum-i);
}
}

function ProvinceChange(){
countryid=document.getElementById(“ddlProvince”).value;
if(countryid==null||countryid==”"){
alert(“请选择所属省”);
CountryDel(“ddlCity”);//清空DropDownList
return false;
}
var countrystring=”";
var posturl=location.protocol+”//”+location.hostname+”//soleweb//AjaxEnjine//AreaShow.aspx?AreaId=”+countryid;
countrystring=openUrl(posturl);
if(countrystring==”-2″){//查询失败
alert(“数据查询失败”);
return false;
}
//分割并写入DropDownList

CountryDel(“ddlCity”);//清空DropDownList
if(countrystring==”"){
return false;
}

var stringarray=countrystring.split(“|”);
for(var i=0;i<stringarray.length;i++){//重写DropDownList
//拆分内部数组
var optionarray=stringarray[i].split(“,”);
var newoption=document.createElement(“option”);
newoption.text=optionarray[0];
newoption.value=optionarray[1];
document.getElementById(“ddlCity”).options.add(newoption);　　
}
}

function openUrl(url)
{
var objxml=new ActiveXObject(“Microsoft.XMLHttp”)
objxml.open(“GET”,url,false);
objxml.send();
retInfo=objxml.responseText;
if (objxml.status==”200″)
{
return retInfo;
}
else
　 {
return “-2″;
}
}
</script>

Html代码

<asp:DropDownList ID=”ddlContry” runat=”server” onchange=”CountryChange()” OnSelectedIndexChanged=”ddlContry_SelectedIndexChanged”>
<asp:ListItem Value=” “>请选择所属国家</asp:ListItem>
</asp:DropDownList>
<asp:DropDownList ID=”ddlProvince” runat=”server” onchange=”ProvinceChange()” OnSelectedIndexChanged=”ddlProvince_SelectedIndexChanged”>
<asp:ListItem Value=” “>请选择所属省</asp:ListItem>
</asp:DropDownList>
<asp:DropDownList ID=”ddlCity” runat=”server”>
<asp:ListItem Value=” “>请选择所属市</asp:ListItem>
</asp:DropDownList>

Aspx.cs代码

protected void Page_Load(object sender, EventArgs e)
{
SoLe.Common.StringFormat sft = new SoLe.Common.StringFormat();
string AreaId = sft.Html_Fn(Request.QueryString["AreaId"].ToString());
StringBuilder AreaString = new StringBuilder();
AreaString.Append(“”);
if (!Page.IsPostBack)
{
//Response.Write(AreaIdValid(AreaId.ToString()));
SoLe.BLL.AreaTable bll = new SoLe.BLL.AreaTable();
DataSet ds = new DataSet();
ds = bll.GetList(” PaterId=” + AreaId.ToString()+” “);
if (!object.Equals(ds, null) && ds.Tables[0].Rows.Count > 0) {
for (int i = 0; i < ds.Tables[0].Rows.Count; i++) {
if (string.IsNullOrEmpty(AreaString.ToString()))
{
AreaString.Append(ds.Tables[0].Rows[i]["Title"].ToString() + “,” + ds.Tables[0].Rows[i]["Id"].ToString());
}
else {
AreaString.Append(“|” + ds.Tables[0].Rows[i]["Title"].ToString() + “,” + ds.Tables[0].Rows[i]["Id"].ToString());
}
}
}
}
Response.Write(AreaString.ToString());
}

　　来源：ITFLY8的blog