Based on cookie the expansion state of zTree tree remains unchanged after refreshing

After zTree tree is refreshed based on cookie, the expansion state remains unchanged.

1. In addition to JS that references jQuery and zTree, JS that references cookie:

< script type="text/javascript" src="~/Scripts/jquery-treeview/lib/jquery.cookie.js" > < /script >

2. JS code:

$(function () {
  //ztree Settings 
  var setting = {
    data: {
      simpleData: {
        enable: true,
        idKey: "id",
        pIdKey: "pId",
        rootPId: null
      }
    },
    callback: {
      onExpand: onExpand,
      onCollapse: onCollapse
    }
  };

  $.ajax({
    type: "POST",
    url: "/Tech/TemplateTypeManage/GetData",
    success: function (data) {
      if (data && data.length != 0) {
        $.fn.zTree.init($("#tree"), setting, data);
        var treeObj = $.fn.zTree.getZTreeObj("tree");
        var cookie = $.cookie("z_tree" + window.location);
        if (cookie) {
          z_tree = JSON2.parse(cookie);
          for (var i = 0; i < z_tree.length; i++) {
            var node = treeObj.getNodeByParam('id', z_tree[i])
            treeObj.expandNode(node, true, false)
          }
        }
      }
    }
  });
});//end $

function onExpand(event, treeId, treeNode) {
  var cookie = $.cookie("z_tree" + window.location);
  var z_tree = new Array();
  if (cookie) {
    z_tree = JSON2.parse(cookie);
  }
  if ($.inArray(treeNode.id, z_tree) < 0) {
    z_tree.push(treeNode.id);
  }
  $.cookie("z_tree" + window.location, JSON2.stringify(z_tree))
}

function onCollapse(event, treeId, treeNode) {
  var cookie = $.cookie("z_tree" + window.location);
  var z_tree = new Array();
  if (cookie) {
    z_tree = JSON2.parse(cookie);
  }
  var index = $.inArray(treeNode.id, z_tree);
  z_tree.splice(index, 1);
  for (var i = 0; i < treeNode.children.length; i++) {
    index = $.inArray(treeNode.children[i].id, z_tree);
    if (index > -1) z_tree.splice(index, 1);
  }
  $.cookie("z_tree" + window.location, JSON2.stringify(z_tree))
}