Select显示多级分类列表

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title>在下拉列表中显示的多级树形菜单</title>
<meta http-equiv="content-type" content="text/html;charset=gb2312">
<script type="text/javascript">
var data =new Array();
data[]= {id:'',pid:'',text:'河北'};
data[]= {id:'',pid:'-1',text:'中国'};
data[]= {id:'',pid:'',text:'莫斯科'};
data[]= {id:'',pid:'',text:'河南'};
data[]= {id:'',pid:'',text:'北京'};
data[]= {id:'',pid:'',text:'湖南'};
data[]= {id:'',pid:'-1',text:'俄罗斯'};
function TreeSelector(item,data,rootId){
this._data = data;
this._item = item;
this._rootId = rootId;
}
TreeSelector.prototype.createTree = function(){
var len =this._data.length;
for( var i= ;i<len;i++){
if ( this._data[i].pid == this._rootId){
this._item.options.add(new Option(".."+this._data[i].text,this._data[i].id));
for(var j=;j<len;j++){
this.createSubOption(len,this._data[i],this._data[j]);
}
}
}
}
TreeSelector.prototype.createSubOption = function(len,current,next){
var blank = "..";
if ( next.pid == current.id){
intLevel =;
var intlvl =this.getLevel(this._data,this._rootId,current);
for(a=;a<intlvl;a++)
blank += "..";
blank += "├-";
this._item.options.add(new Option(blank + next.text,next.id));
for(var j=;j<len;j++){
this.createSubOption(len,next,this._data[j]);
}
}
}
TreeSelector.prototype.getLevel = function(datasources,topId,currentitem){
var pid =currentitem.pid;
if( pid !=topId)
{
for(var i = ;i<datasources.length;i++)
{
if( datasources[i].id == pid)
{
intLevel ++;
this.getLevel(datasources,topId,datasources[i]);
}
}
}
return intLevel;
}
</script>
</head>
<body>
<select id="myselect"></select>
<script language=javascript type="text/javascript">
var ts = new TreeSelector(document.getElementById("myselect"),data,-);
ts.createTree();
</script>
</body>
</html>