<script>
      window.onload=function (){
        var login_btn=Document.getElementById('login'),
            login_box=Document.getElementById('login_box'),
            close=Document.getElementById('close');

      function addEvent (ele,type,handler){
         if (ele.addEventListener){
             ele.addEventListener(type,handler,false)
         }else if (ele.attachEvent) {
             ele.attachEvent('on'+type,handler)
         }else{         
             ele['on'+type]=handler;
         }
      }

      function showLogin () {
        login_box.style.display='block'; 
      }

      function hideLogin () {
        login_box.style.display='none' ; 
      }

      addEvent(login_btn,'click',showLogin);
      addEvent(close,'click',hideLogin);
  }
    </script>

哪里错了呢，麻烦大神帮指出来