Функция считывает одно и тоже значение

<script type="text/javascript">

function loaded() {
alert(document.getElementById('code').value);
/*
var data = document.getElementById('code').value;

var http = new XMLHttpRequest();
http.onreadystatechasnge = function() {
http.readyState == 4 && http.status == 200) {
document.getElementById('top').innerHTML = http.responseText;
}
}
http.open('POST', 'loaded.php', true);
http.setRequestHeader('Content-type','application/x-www-form-urlencoded');
http.send(data);
*/
}

</script>
<?php
$link = mysql_connect('localhost', 'root', '123') or die(mysql_error());
mysql_query("SET NAMES 'UTF8'", $link);
mysql_select_db('ajax') or die(mysql_error());
$result = mysql_query("SELECT * FROM cart", $link);
$total = mysql_num_rows($result);

print <<<HERE
КОЛИЧЕСТВО ($total)
<br>
<hr>
<table>
<tr>
HERE;
$result = mysql_query("SELECT * FROM product", $link);
$total = mysql_num_rows($result);
for ($i = 1; $i <= $total; $i++) {
$row = mysql_fetch_array($result);
print <<<HERE
<td style='border:solid 1px black; width:150px; text-align:center'>$row[name]<br>
<div id='top'>
<input type='hidden' id='code' value='$row[code]'>
<input type='button' value='Добавить' onclick='loaded()'>
</div>
</td>
HERE;
}

?>
</tr>
</table>