Use wp_localize_script() to expose PHP values such as the AJAX URL, a nonce or the site URL to your JS file.

functions.php

function lotgrafix_enqueue_scripts() {
    wp_enqueue_script( 'lotgrafix-main', get_template_directory_uri() . '/js/main.js', array(), '1.0.0', true );

    wp_localize_script( 'lotgrafix-main', 'lotgrafixData', array(
        'ajaxUrl' => admin_url( 'admin-ajax.php' ),
        'nonce'   => wp_create_nonce( 'lotgrafix_nonce' ),
        'siteUrl' => home_url(),
    ) );
}
add_action( 'wp_enqueue_scripts', 'lotgrafix_enqueue_scripts' );

main.js

console.log( lotgrafixData.siteUrl );