<?php
add_action( 'wp_enqueue_scripts', 'my_enqueue_scripts' );
function my_enqueue_scripts() {
    if (!is_user_logged_in()) {
        return;
    }
    // Register custom variables for the AJAX script.
    wp_localize_script( 'script', 'myScriptVars', [
        'root'  => esc_url_raw( rest_url() ),
        'nonce' => wp_create_nonce( 'wp_rest' ),
    ] );
}