如何在JavaScript文件中包含PHP $ _SESSION值？

Question

I use $_SESSION['siteRoot'] to store the root address of my website in (it's basically a framework so this can change depending on the URL used to access the site). I need to use this value in some of my javascript files...

Up until now I've been including my js files as .php , and putting the following code at the top of my js files, like so:

<?php
    header("Content-type: application/javascript");
    session_start();
?>

This has been working fine on my local-host for testing - but when I upload it to the live server I noticed that my session was being reset every time I reload the page, and after a day of debugging finally discover that it's the session_start(); line in my java-script files that is causing this behavior.

I've tried the following:

if (!isset($_SESSION))
    {
    session_start();
    }

if (session_id() == '')
    {
    session_start();
    }

if (session_status() !== PHP_SESSION_ACTIVE)
    {
    session_start();
    }

and also just leaving out the session_start altogether. If I don't start the session then I can't use the variables (obviously...), but I can't find a way of starting it that doesn't wipe the session I already created in my main page.

Any ideas?

Answer 1

The problem was not caused by the session itself exactly, but because I hadn't included my class autoloader before calling the session, and so my custom classes were not surviving the deserialize process (even though it's a javascript file and I don't use any of said classes!)

I changed my javascript code to:

<?php
    include ('include/autoloader.php');
    header("Content-type: application/javascript");
    session_start();
?>

and everything works fine. Easy to forget when you're not using any of the serialized classes on that page!