让载入页面竖滚动条消失

function frameResize_bb(){
     
     document.getElementById("bb").style.height=window.IframeName.document.body.scrollHeight+20+"px";
     
    }
        
    
             </SCRIPT>
    
             <IFRAME id="bb" NAME="IframeName" SRC="<!-- @@ VAR NAME=@FirstLink@-->" WIDTH=100% HEIGHT=400 MARGINWIDTH=0 MARGINHEIGHT=0 HSPACE=0 VSPACE=0 FRAMEBORDER=0 SCROLLING=AUTO BORDERCOLOR="#000000" ALLOWTRANSPARENCY="true"
    onload="frameResize_bb()"></IFRAME>