script moi - menu getElementById ( script cũ )

function MM_openBrWindow(theURL,winName,features) { //v2.0
  window.open(theURL,winName,features);
}

function menu( id)
{
 if(document.getElementById(id).style.display=='none')
 {
  document.getElementById(id).style.display='block'; 
 }
 else
 {
  document.getElementById(id).style.display='none'; 
  
 }
}

<ul>

   <li><a onclick="menu('active20')" href="#>nhóm cha</a>

      <ul id="active20" style="display: none;">

        <li><a href='#'>nhóm con</a></li>

     </ul> 

   </li> 

</ul> 

#----------------------------------------------------------------#

$('.b-shop-oop > a').click(function(){     
 var id=$(this).attr("dataid");
 $(".b-shop-oop2").hide();
 $('.sss_'+id).show();
 return false;

}); 

return false ---> là không cho chuyển trang

<ul>

   <li class='b-shop-oop'><a dataid='20' href='#'>nhóm cha</a>

      <ul class='b-shop-oop2 sss_20'>

          <li><a href='#'>nhóm con</a></li> 

      </ul> 

   </li> 

</ul>  

 linkweb : devprosft