DNI show div based on landing page, continue showing div entire session

I have about 60 landing pages that use different phone numbers on them. I am using a combination of WordPress and Advanced Custom Fields to place the phone numbers on their respective pages.

I am being asked to show a <div> based on the landing page URL that will not only show the phone number assigned to that page, but, keep showing the <div> (and phone number) regardless of what page the user navigates to on the website.

I have found little to no support on how to make the <div> remain visible throughout the entire session until the user closes the window.

I am thinking that this will somehow revolve around a cookie and Dynamic Number Insertion but I have no real progress to speak of. Should this be done using PHP or JS? Does a plugin exist that would allow for this on WordPress? I’m open to all suggestions.

Answer

Please try this code. Like @John C mentioned, WP Engine doesn’t recommend Cookie nor PHP Session for the sake of performance and security. This is pure JavaScript code, and I think this will solve your problem.

Code in your Post/Page template file:

<div id="phone-number"></div>
<?php if( get_field('phone_number') ): ?>
    <script type="text/javascript">
        let phone_number = "<?php the_field('phone_number'); ?>";
    </script>
<?php endif; ?>

Code in your theme JavaScript file:

<script type="text/javascript">
    // in the case of the div data is persistent on the same site
    // let storage = localStorage;

    // in the case of the div data is persistent in the same tab, but not in new tab
    let storage = sessionStorage;
    
    let key = "phone_number"; // storage key

    var global_phone_number = storage.getItem(key);

    // check if storage data is set before
    if (null === global_phone_number) {
        // if not set the data on page into storage
        global_phone_number = phone_number ? phone_number : '';
        storage.setItem(key, global_phone_number);
    }
    document.getElementById('phone-number').innerHTML = global_phone_number;
</script>