Conditional for 404 page not work

Question

I am trying to add a conditional to enqueue script only for 404 page. Theoretically I would have to use is_404() right? Well it does not work:

if ( is_page_template('404.php') ) {
    add_action('wp_enqueue_scripts', 'scripts_404');
}

if ( is_404() ) {
    add_action('wp_enqueue_scripts', 'scripts_404');
}

nor does the is_page_template work. However if I add this line without conditionals, it works just fine. Any ideas or am I missing something?

Thanks in advance.

Answer 1

You should wrap your enqueue/register function in your conditional, not your add_action()

You can try something like this using the is_404() conditional check

function enqueue_404_script() {
    if(is_404()) {
        //do what you need to do
    }
}
add_action( 'wp_enqueue_scripts', 'enqueue_404_script' );