echo '<script type="text/javascript">(function(){setTimeout(function(){document.location.replace('add.php');}, 5000);})();</script>';
Ошибка Parse error: syntax error, unexpected T_STRING, expecting ',' or ';'
echo '<script type="text/javascript">(function(){setTimeout(function(){document.location.replace('add.php');}, 5000);})();</script>';
echo '<script type="text/javascript">(function(){setTimeout(function(){document.location.replace(" ;add.php;");}, 5000);})();</script>';
echo '<script type="text/javascript">(function(){setTimeout(function(){document.location.replace(\'add.php\');}, 5000);})();</script>';