Prevent CSS/JS loading when plugin is not used

I have a WordPress theme (the7) that includes the Visual Composer plugin. This is good for my clients editing stuff in the back end, but it also adds unnecessary CSS and JS to every page load on the front end. How can I remove these?

The lines it adds are:

<link rel="stylesheet" id='js_composer_front-css'  href="https://wordpress.stackexchange.com/questions/255071/[domain]/wp-content/plugins/js_composer/assets/css/js_composer.min.css?ver=5.0.1" type="text/css" media="all" />

<script type="text/javascript" src="[domain]/wp-content/plugins/js_composer/assets/js/dist/js_composer_front.min.js?ver=5.0.1"></script>

I found this question which gives a possible method, but I can’t get it to work.

I tracked down where the specific CSS file is loaded from, it’s in a class Vc_Base in this function:

public function enqueueStyle() {
    $post = get_post();
    if ( $post && preg_match( '/vc_row/', $post->post_content ) ) {
        wp_enqueue_style( 'js_composer_front' );
    }
    wp_enqueue_style( 'js_composer_custom_css' );
}

So I set up this in my functions.php:

function inf_remove_junk()
{
    wp_dequeue_style('js_composer_front');
    wp_dequeue_style('js_composer_custom_css');
    wp_dequeue_script('wpb_composer_front_js');

    // also tried this
    remove_action('wp_enqueue_scripts', array('Vc_Base', 'enqueueStyle'));
}

if (!is_admin()) {
    add_action('wp_head', 'inf_remove_junk');
}

The inf_remove_junk function definitely executes, but it doesn’t remove the CSS. Does it need to hook into a different point or do something else?

You need to use action wp_enqueue_scripts except wp_head like:

function inf_remove_junk() {
    if (!is_admin()) {
          wp_dequeue_style('js_composer_front');
          wp_dequeue_style('js_composer_custom_css');
          wp_dequeue_script('wpb_composer_front_js');
     }

}

add_action( 'wp_enqueue_scripts', 'inf_remove_junk' );

But it remove the scripts from front end.

1. I think on archive pages VC does not execute it’s shortcode. So you can check is_archive() condition instead of is_admin().

2. Or you can check the shortcode from content and remove assets like:

   function inf_remove_junk() {

   // 1. Check shortcode exist in post content and disable scripts.
           global $post;
           if ( stripos($post->post_content, '[YOUR_SHORTCODE]') ) {
   
   // or
   
   // 2. Disable scripts on all pages except single page, post, custom Post etc.
   
           if ( ! singular() ) {
   
   // or
   
   // 3. Disable on archive, 404 and search page
           if ( is_archive() || is_404() || is_search() ) {
                 wp_dequeue_style('js_composer_front');
                 wp_dequeue_style('js_composer_custom_css');
                 wp_dequeue_script('wpb_composer_front_js');
            }     
   

   }
   add_action( ‘wp_enqueue_scripts’, ‘inf_remove_junk’ );

Also, For premium plugin support you need to contact plugin author for better answer.