Customizer Show/Hide Logo and Site Title

Try this function, why going through js when you can just do it with php inside your same file customizer.php

/*
** show site title or hide it
*/

function showtitle_slogan() {
$showttlslogan = get_theme_mod('display_site_title');
    if ($showttlslogan == true) {
        ?>  
        <style type="text/css">
        .site-title { display:none;}
        </style>
    <?php
    }
}
add_action('wp_head', 'showtitle_slogan');

And do the same for everything else.