zxcvbn-async.min file is loading for all pages

PR doesnt register that script so it wont help whether you use an older version or newer version. the problem the way that script is being registered is wrong. You can however deregister, register again and enqueue back the script.

add_action('wp_enqueue_scripts','zxcvbn_script_fix',1);
function zxcvbn_script_fix(){
    wp_deregister_script( 'zxcvbn-async' );
    wp_register_script('zxcvbn-async', '//YOUDOMAIN.com/wp-includes/zxcvbn-async.min.js',array(),'1.0');
}

Butter vs WordPress

Butter is an API-based WordPress alternative that lets you build a blog without ditching your tech stack.

If you develop in Ruby, Python, or node.js, chances are you’re not in love with WordPress. Butter integrates into your existing codebase so you can build your blog on your own terms.

Plugin API/Action Reference/customize preview init

This action hook allows you to enqueue assets (such as javascript files) directly in the Theme Customizer only. To output saved settings onto your live site, you still need to output generated CSS using the wp_head hook.

Generally, this hook is used almost exclusively to enqueue a theme-customizer.js file for controlling live previews in WordPress’s Theme Customizer.

 

.. add_action( 'customize_preview_init', 'mytheme_customizer_live_preview' );