Question

I want to use a PHP variable as a javascript variable – specifically I want to user the PHP variable session_id(); and use this as a javascript variable.

<?php
$php_var = session_id();
?>
<script language="JavaScript" type="text/javascript">
js_var = <?php echo($php_var ?>;
</script>

This seems like it should work for me but it doesnt can anyone suggest a better way?

Answer 1

The best method i can think of looks like this:

<?php
$php_var = session_id();
?>
<script type="text/javascript">
    var js_var = <?php echo json_encode($php_var); ?>;
</script>

PHP’s json_encode-function is always producing valid JavaScript, which is not ensured if you are simply outputting random values. If you decide not to use json_encode(), you should at least enclose the php-value with quotes to prevent syntax errors. Be aware of escaping!

<?php
$php_var = session_id();
?>
<script type="text/javascript">
   var js_var = "<?php echo $php_var; ?>";
</script>