var left_div="left";
var right_div="right";
function change(id1,id2){
  var con1=document.getElementById(id1);
  var con2=document.getElementById(id2);
  if(con1.offsetHeight<con2.offsetHeight){con1.style.height=con2.offsetHeight+"px"; }
  else {con2.style.height=con1.offsetHeight+"px";}
}

window.onload=function (){try{change(left_div,right_div);}catch(e){}}