Hold Tracking Scripts Until the Visitor Consents

// Script handle => consent category (functional, preferences, statistics, marketing).
$wpide_consent_scripts = array(
    'google-analytics' => 'statistics',
    'facebook-pixel'   => 'marketing',
);

add_filter( 'script_loader_tag', function ( $tag, $handle ) use ( $wpide_consent_scripts ) {
    if ( empty( $wpide_consent_scripts[ $handle ] ) || ! class_exists( 'WP_HTML_Tag_Processor' ) ) {
        return $tag;
    }

    $tags = new WP_HTML_Tag_Processor( $tag );

    while ( $tags->next_tag( 'script' ) ) {
        $tags->set_attribute( 'type', 'text/plain' );
        $tags->set_attribute( 'data-wpide-consent', $wpide_consent_scripts[ $handle ] );
    }

    return $tags->get_updated_html();
}, 20, 2 );

add_action( 'wp_footer', function () {
    ?>
<script>
(function () {
    function allowed(category) {
        if (typeof window.wp_has_consent === 'function') { return window.wp_has_consent(category); }
        return /(?:^|; )wpide_consent=granted/.test(document.cookie);
    }
    function release() {
        document.querySelectorAll('script[type="text/plain"][data-wpide-consent]').forEach(function (old) {
            if (!allowed(old.getAttribute('data-wpide-consent'))) { return; }
            var s = document.createElement('script');
            Array.prototype.forEach.call(old.attributes, function (a) {
                if (a.name !== 'type' && a.name !== 'data-wpide-consent') { s.setAttribute(a.name, a.value); }
            });
            if (!old.src) { s.text = old.text; }
            old.parentNode.replaceChild(s, old);
        });
    }
    release();
    document.addEventListener('wp_listen_for_consent_change', release);
    document.addEventListener('wpide:consent', release);
})();
</script>
    <?php
}, 99 );