Disable Back Button using Javascript

<html>
<head>
<script type="text/javascript">
    window.history.forward();
    function noBack(){ window.history.forward(); }
</script>
</head>
<body  onload="noBack();" onpageshow="if (event.persisted) noBack();" onunload="">

<a href="to.html">This is it</a>

</body>

</html>

This must be installed on the page before you don't want people to go back.