function gettableheight()
{

var getheight = document.getElementById('cantertext').scrollHeight;
document.getElementById('leftnavi').style.height=getheight+'px';
}

function addEvent( obj, type, fn ){ 
   if (obj.addEventListener){ 
     obj.addEventListener( type, fn, false );
   }
   else if (obj.attachEvent){ 
     obj["e"+type+fn] = fn; 
     obj[type+fn] = function(){ obj["e"+type+fn]( window.event ); } 
     obj.attachEvent( "on"+type, obj[type+fn] ); 
   } 

}

addEvent(window, 'load', gettableheight);