shortcode in ajax

// Constructor / initialize plugin
    function Youtube_shortcode()
    {
        // Load our shortcode only on the frontend
        if ( !is_admin() || FALSE !== strpos($_SERVER['SCRIPT_NAME'], 'wp-admin'))
        {
            // Is it a mobile phone?
            $this->detect_mobile();
            // Guess once host language (used for Youtube's old embed code = Flash only)
            $this->get_hl();
            // do_shortcode() is registered as a default filter on 'the_content' with a priority of 11.
            // To make videos appear on post excerpts follow this guide: https://bloggingsquared.com/blogging-tips/make-shortcodes-work-in-all-wordpress-post-excerpts/
            add_shortcode('youtube_sc', array($this, 'output_html'));
            add_action('wp_enqueue_scripts', array($this, 'output_css'));
        }
        // Allow the button to appear on any rich text editor (i.e. text editor in a widget)

		add_action('admin_init', array($this, 'setup_tinymce_button'));
    }

I also corrected this feature by
/**
* Check if WordPress is doing ajax or not. Helpful when testing for admin
* templates because is_admin() will be true even though the user might not be
* on admin, or even logged in.
*/
function is_ajax()
{
return defined( ‘DOING_AJAX’ ) && DOING_AJAX;
}