Here, i gave client side check/uncheck node child node to parent node as well as parent to child..


 <script type="text/javascript" language="javascript">      
    
 function UpdateAllChildren1(nodes, checked)
{
   var i;
   for (i=0; i<nodes.get_count(); i++)
   {
   
       if (checked)
       {           
           nodes.getNode(i).check();
       }
       else
       {
           nodes.getNode(i).set_checked(false);
       }
       
       if (nodes.getNode(i).get_nodes().get_count()> 0)
       {          
           UpdateAllChildren1(nodes.getNode(i).get_nodes(), checked);         
                        
       }
   }
}
     
 function Checkparentnode(node, isChecked,eventArgs)
 {
            
    if(node.get_parent() != null)
    {
      if(isChecked)
      {
        node.get_parent().set_checked(true);
        Checkparentnode(node.get_parent(), isChecked,eventArgs);
      }
      else
      {
          node.get_parent().set_checked(false);
          Checkparentnode(node.get_parent(), isChecked,eventArgs);
      }
    }            

 }
     
function AfterCheck(childNodes, isChecked,eventArgs)
{          
        
    UpdateAllChildren1(childNodes, isChecked);    
    var node = eventArgs.get_node();
    var parentNode = node.get_parent();    
    var cNodes = eventArgs.get_node().get_nodes();        
    Checkparentnode(node, isChecked,eventArgs);      

}

function clientNodeChecked1(sender, eventArgs)
{
   var childNodes = eventArgs.get_node().get_nodes();   
   var isChecked = eventArgs.get_node().get_checked();
   AfterCheck(childNodes, isChecked,eventArgs);

}
      
</script>
  <telerik:RadTreeView ID="RadTreeView1" runat="server" CheckBoxes="True"  OnClientNodeChecked="clientNodeChecked1" >
   </telerik:RadTreeView>

Hello Steinar Simonsen,

Do you have any problems with the code?

Regards,
Veselin Vasilev
the Telerik team