<div> <input type="text" class="input" /> <input type="text" class="input" /> </div>
<script type="text/javascript">
i=document.getElementsByClassName('input');
i[0].onkeyup=i[1].onkeyup=i[0].onchange=i[1].onchange=function(){
if(+i[0].value>+i[1].value){i[0].parentNode.appendChild(i[0]).focus()}
}
</script>