Wrap wp_enqueue_script() in a conditional tag so the file loads only where it is needed.

function lotgrafix_enqueue_conditional() {
    if ( is_page( 'contact' ) ) {
        wp_enqueue_script( 'lotgrafix-contact', get_template_directory_uri() . '/js/contact.js', array(), '1.0.0', true );
    }
}
add_action( 'wp_enqueue_scripts', 'lotgrafix_enqueue_conditional' );

Other useful conditions: is_front_page(), is_singular( 'post' ), is_category() and is_shop().