JS implementation code of level three drop-down menu

function list(idstr){
var name1="subtree"+idstr;
var name2="img"+idstr;
var objectobj=(name1);
var imgobj=(name2);
//alert(imgobj);
if(=="none"){
for(i=1;i<22;i++){
var name3="img"+i;
var name="subtree"+i;
var o=(name);
if(o!=undefined){
="none";
var image=(name3);
//alert(image);
="<%=basePath%>admin/images/";
if(idstr>12&&idstr<20){
("subtree11").="";
("img11").src="<%=basePath%>admin/images/";
}
}
}
="";
="<%=basePath%>admin/images/";
}
else{
="none";
="<%=basePath%>admin/images/";
}
}