How can I go about passing data from one php file to another via AJAX in Elgg?

data_from_here.php

<?php

    $entity = elgg_extract('entity', $vars, FALSE);
    $guid = $entity -> guid;

    require_js('javascript_file.js');

javascript_file.js

require(['elgg/Ajax'], Ajax => {

    var ajax = new Ajax();

    $('.glyphicon-zoom-in').click(function(event) {
        ajax.view('my_app/data_to_here', {
            data: {
                // I would like to pass $guid from data_from_here.php to guid here,
                // so that js_guid will be == $guid from data_from_here.php
                js_guid: $guid // Save the $guid from data_from_here.php in here
            },
        }).then(body => {
            $( '.full-image-view' ).html(body);
        })
    });
});

data_to_here.php

// This is the file called by AJAX in javascript_file.js
// I would like to echo $guid from data_from_here.php here
// How do I get it from javascript_file.js
<?php

    echo '<div class="full-image-view">$js_guid</div>';