经php中urlencode编码后如何用js将之还原

经php中urlencode编码后如何用js将之还原
例如

<?php
$str = http://ss.com;
$str = urlencode($str);
echo "<script type="\'text/javascript\'">
var s = decodeURIComponent(\'"经PHP编码后的url"\');
document.write(s)
</script> ";
?>