if child node checked after that root will be checked

var TreeView = "<%=TreeView1.ClientID %>"
var checkboxs = document.getElementById(TreeView).getElementsByTagName("INPUT")
for(i=0;i<checkboxs.length;i++)>
{
  if(checkboxs[i].type == "checkbox"
    &&  checkboxs[i].name.substr(0,TreeView.length) == TreeView
    && checkboxs[i].checked )
  {
      //Do what you want to do.
  }
}