Ti do' un esempio semplice di interazione tra php e js

codice:
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">

<html>
<head>
<title>Untitled</title>
</head>
<body>
<?php 
$array = array("salve","ciao","bye bye","au revoir","salut");
?>
<script language="JavaScript" type="text/javascript">
<!--
<?php 
foreach($array as $key => $value) { ?>
 alert("<? print $value ?>");<?php 
}
?> 
//-->
</script>

</body>
</html>
Che da'
codice:
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">

<html>
<head>
<title>Untitled</title>
</head>
<body>
<script language="JavaScript" type="text/javascript">
<!--
 alert("salve"); alert("ciao"); alert("bye bye"); alert("au revoir"); alert("salut"); 
//-->
</script>

</body>
</html>