<script type='text/javascript'>
function highlight(element){

if(element.style.backgroundColor != '#FFFFCC')
element.style.backgroundColor = '#FFFFCC';
elseif(element.style.backgroundColor == '#FFFFCC')
element.style.backgroundColor = '#FFF';
}
</script>


<input type="text" onFocus="highlight(this)"  onBlur="highlight(this)"/>