I have a javascript file that needs a value from a variable in a php script in which the JS file is being called.
<?
$sid = session_id();
?>
<html>
<head>
<script src="javascript.js" type="text/javascript"></script>
...
How can i get $sid into the js file for use?
<html>
<head>
<script src="javascript.js" type="text/javascript"></script>
<script type="text/javascript">
var myFile = 'myfile.php?sid=' + "<?php echo session_id() ?>";
$('#stuff').fadeOut("fast").load(myFile).fadeIn("fast");
</script>
The order of inclusion somewhat depends on what is inside javascript.js. If you are using the declared 'myFile' variable inside, declare it first. If it's just a lib, e.g. jQuery, declare it afterwards.
Why on earth do you pass SID explicity? It should be passed throught cookies by PHP. Any other variable could be passed through sessions.
$('#stuff').fadeOut("fast").load('myfile.php?sid=<?php echo session_id() ?>').fadeIn("fast");
Read more about client/server languages and differences between them.
<?
$sid = session_id();
?>
<html>
<head>
<script type="text/javascript">
var sid = '<?= $sid ?>';
</script>
<script src="javascript.js" type="text/javascript"></script>
Now you can use the sid variable in javascript.js, or any other JS code you load AFTER this.