Hi i found out the way


Sys.WebForms.PageRequestManager.getInstance().add_initializeRequest(
       function (){
           var arrSelects = document.getElementsByName('select')
           for(var i=0;i<arrSelects.length;i++){
               arrSelects[i].style.display = 'none'
           }
       }
      )

but now another problem. document.getElementsByName('select') returns
nothing , does anyone know why?

ps: running javascript:document.getElementsByName('select').length in
browser address bar  returns 5