Java Script for Making HTML Control Toogle

<script type="text/javascript" language="javascript">
var prev='texxt';
function Showdata(indexx)
{
var tblprev=document.getElementById(prev);
if(prev !=indexx)
{
tblprev.style.display = 'none';
}
prev=indexx;
var tbl1=document.getElementById(indexx);
if(tbl1.style.display == 'block')
tbl1.style.display = 'none';
else
tbl1.style.display = 'block';
}
</script>