<html>
<head>
<script>
function goBack()
{
window.history.go(-2)
}
</script>
</head>
<body>
<input type="button" value="Go 2 pages back" onclick="goBack()">
<p>Notice that clicking on the "Go 2 pages back" button here will not result in any action, because there is no previous URL in the history list.</p>
</body>
</html>