$string = iconv('cp1251', 'utf-8', $string);
$string = iconv('utf-8', 'cp1252', $string);
$string = iconv('cp1251', 'utf-8', $string);
<body>
start
<script type="text/javascript">
// <!--
document.write("<!"+'--');
// -->
</script>
<script type="text/javascript" src="alert.js"></script>
<script type="text/javascript">
// <!--
document.write(" -"+"->");
// -->
</script>
end
</body>
* This source code was highlighted with Source Code Highlighter.
document.write(" -"+"->");
а // -->
после него.