The operation of Checkbox in the Asp.Net2.0 permission tree

The TreeView control of asp.net2.0 is used here in conjunction with JavaScript to implement part of the privilege tree.
Suppose there are three rules in the permission tree:
1. If the node can be accessed, its parent node must also be accessed;
2. If the node can be accessed, its children can also be accessed;
3. If the node is not accessible, its children cannot be accessed either.

The code is as follows:
// gets the parent element
of the element specified tagName function public_GetParentByTagName(element, tagName)
{
      var parent = element.parentNode;
      var upperTagName = tagName.toUpperCase();
      // if the element is not the desired tag, continue to
      while (parent && (parent.tagName.toUpperCase() != upperTagName))
      {
              parent = parent.parentNode ? parent.parentNode : parent.parentElement;
      }
      return parent;
}

// set the parent node Cheched of the node -- if this node is accessible, its parent must also be able to access
function setParentChecked(objNode)
{
      var objParentDiv = public_GetParentByTagName(objNode,"div");
      if(objParentDiv==null || objParentDiv == "undefined")
      {
              return;
      }
      var objID = objParentDiv.getAttribute("ID");
      objID = objID.substring(0,objID.indexOf("Nodes"));
      objID = objID+"CheckBox";
      var objParentCheckBox = document.getElementById(objID);
      if(objParentCheckBox==null || objParentCheckBox == "undefined")
      {
              return;
      }
      if(objParentCheckBox.tagName!="INPUT" && objParentCheckBox.type == "checkbox")
      return;
      objParentCheckBox.checked = true;
      setParentChecked(objParentCheckBox);
}

// sets the child node uncheched of the node -- if this node is not accessible, his child node cannot access
either function setChildUnChecked(divID)
{
      var objchild = divID.children;
      var count = objchild.length;
      for(var i=0;i < objchild.length;i++)
      {
              var tempObj = objchild[i];
              if(tempObj.tagName=="INPUT" && tempObj.type == "checkbox")
              {
                      tempObj.checked = false;
              }
              setChildUnChecked(tempObj);
      }
}

// sets the node's child node cheched -- if this node can access
, all of its children can also access
function setChildChecked(divID)
{
      var objchild = divID.children;
      var count = objchild.length;
      for(var i=0;i < objchild.length;i++)
      {
              var tempObj = objchild[i];
              if(tempObj.tagName=="INPUT" && tempObj.type == "checkbox")
              {
                      tempObj.checked = true;
              }
              setChildChecked(tempObj);
      }
}

// trigger event
function CheckEvent()
{

      var objNode = event.srcElement;

      if(objNode.tagName!="INPUT" || objNode.type!="checkbox")
      return;

      if(objNode.checked==true)
      {
              setParentChecked(objNode);
              var objID = objNode.getAttribute("ID");
              var objID = objID.substring(0,objID.indexOf("CheckBox"));
              var objParentDiv = document.getElementById(objID+"Nodes");
              if(objParentDiv==null || objParentDiv == "undefined")
              {
                      return;
              }
              setChildChecked(objParentDiv);
      }
      else
      {
              var objID = objNode.getAttribute("ID");
              var objID = objID.substring(0,objID.indexOf("CheckBox"));
              var objParentDiv = document.getElementById(objID+"Nodes");
              if(objParentDiv==null || objParentDiv == "undefined")
              {
                      return;
              }
              setChildUnChecked(objParentDiv);
      }
}

Then bind TreeView to js in the page_load event:

this.TreeView1.Attributes.Add("onclick", "CheckEvent()");