Question

I am trying to delay PHP execution until a cookie is set through JavaScript. The code is below, I trimmed the createCookie JavaScript function for simplicity (I’ve tested the function itself and it works).

<?php
if(!isset($_COOKIE["test"])) {
    ?>
    <script type="text/javascript">
        $(function() {
            // createCookie script
            createCookie("test", 1, 3600);
        });
    </script>
    <?php
    // Reload the page to ensure cookie was set
    if(!isset($_COOKIE["test"])) {
        header("Location: http://localhost/");
    }
}
?>

At first I had no idea why this didn’t work, however after using microtime() I figured out that the PHP after the <script> was executing before the jQuery ready function. I reduced my code significantly to show a simple version that is answerable, I am well aware that I am able to use setcookie() in PHP, the requirements for the cookie are client-side.

I understand mixing PHP and JavaScript is incorrect, but any help on how to make this work (is there a PHP delay? – I tried sleep(), didn’t work and didn’t think it would work, since the scripts would be delayed as well) would be greatly appreciated.

Answer 1

This can’t be done within a single request. PHP runs first, then JavaScript. Even incremental loading won’t help, because cookies are sent via headers and those have already been sent by the time PHP runs.

However, you can let the JavaScript set the cookie and then reload the page once it’s done by using location.reload(). PHP would then only need to print the JavaScript, like so:

<?php
if(!isset($_COOKIE["test"])) {
    ?>
    <script type="text/javascript">
        $(function() {
            // createCookie script
            createCookie("test", 1, 3600);
            // reload the page, which would send the cookie at the next request
            location.reload();
        });
    </script>
    <?php
    // stop execution and wait for JavaScript to call you again.
    exit;
}
?>