Find Enqueued WP Script Handles

snippet.php

function wpa54064_inspect_scripts() {
    global $wp_scripts;
    foreach( $wp_scripts->queue as $handle ) :
        echo $handle;
    endforeach;
}
add_action( 'wp_print_scripts', 'wpa54064_inspect_scripts' );



// DEFER SCRIPTS WITH HANDLES FROM ABOVE

function mind_defer_scripts( $tag, $handle, $src ) {
    $defer = array(
        'wp-polyfill',
        'marketo-forms-library',
        'marketo-forms-activator',
        'wedc-success-stories-activator',
        'app-js',
        'cost-doing-business-tool',
        'addthis_ui_vendor',
        'addthis_ui_app',
        'image-map-pro-dist-js',
        'google-jsapi',
        'monsterinsights-frontend-script',
        'jquery-ui-autocomplete',
        'jqueryfusion-scripts',
        'contact-coleman-activator',
        'cookie-notice-front',
        'cost-of-living-activator',
        'admin-bar',
        'cookie-notice-front',
        'contact-coleman-activator',
        'cost-of-living-activator',
        'dwd-vet-job-search-activator',
        'jquery-ui-autocomplete',
        'dwd-vet-job-search-predictive-search',
        'dwd-job-search-activator',
        'wedc-events-activator',
        'image-map-pro-dist-js',
        'marketo-forms-library',
        'marketo-forms-activator',
        'rql-countto',
        'regional-quality-of-life-activator',
        'wedc-success-stories-activator',
        'wpml-legacy-dropdown-0',
        'monsterinsights-vue-vendors',
        'monsterinsights-vue-common',
        'monsterinsights-vue-frontend',
        'slick',
        'matchHeight',
        'zoomapp-js',
        'jqueryfusion-scripts',
        'ulp',
        'ulptabs',
    );
    if ( in_array( $handle, $defer ) ) {
        return '<script src="' . $src . '" defer="defer" type="text/javascript"></script>' . "\n";
    }

    return $tag;
}
add_filter( 'script_loader_tag', 'mind_defer_scripts', 10, 3 );