How to reach php $_SESSION array in javascript?

Question

I am trying to build some javascript function and I need to check if the users are logged in or not. When a user log in to my site I set a variable in session array named is_logged. I want to reach that variable in javascript is it possible??? I tried some ways but did not work like following:

var session = "<?php print_r $_SESSION['is_logged']; ?>";
alert(session);

and:

var session = '<?php echo json_encode($_SESSION['is_logged']) ?>';
alert(session);

It is either show a text or never alert at all

Answer 1

Just echo it:

var session = <?php echo $_SESSION['is_logged']?'true':'false'; ?>;
alert(session);

You need tertiary operator, as false is echoed as empty string so it would lead to var session = ; which is a JS syntax error.

Answer 2

If you want to reach all elements of $_SESSION in JavaScript you may use json_encode,

<?php
session_start();
$_SESSION["x"]="y";
?>

<script>
 var session = eval('(<?php echo json_encode($_SESSION)?>)');
 console.log(session);

//you may access session variable "x" as follows
alert(session.x);
</script>

But note that, exporting all $_SESSION variable to client is not safe at all.