External JavaScript and PHP

How do I create a javascript variable from a php variable using External JavaScript and PH?

My script so far:


<?php
$url = "http://localhost";

header('Content-type: text/javascript');

echo 'var url = <?php echo $url; ?>';

echo 'alert(url);';


?>

Close, but try this instead

$url = "http://localhost"; 
header('Content-type: text/javascript');
echo 'var url = "' . $url . '";';
echo 'alert(url);';

php within javascript within php is brand new to me as of today. Who would’ve thunk?

Thanks for your help cpradio.