后台如何获取所有选中的子节点或者不同父节点下的子节点

比如不同的父节点下的子节点也要获取一起获取

[{"children":[],"id":1,"isParent":true,"name":"浙江省"},{"children":[],"id":2,"isParent":true,"name":"江苏省"},{"children":[{"children":[],"id":1,"isParent":false,"name":"测试"},{"children":[],"id":2,"isParent":false,"name":"111"}],"id":3,"isParent":false,"name":"test"}...

var treeObj = $.fn.zTree.getZTreeObj("treeDemo");
var node = treeObj.getCheckedNodes(true);
     if(node.length==0){
         alert('请至少选择一项');
return false;
     }
var nodes="";
for(var i=0;i<node.length;i++){
         if(node[i].isParent==false){
             nodes+=node[i].id;
         }
    }
这样的是能获取的，我可能哪里想歪了...不好意思~~