jQuery(document).ready( function($) {
    $("#wp-admin-bar-maintenance").click( function() {
        var data = { action: 'maintenance' };

        $.post(maintenance.ajaxurl, data, function(response) {
            $(".maintenance-icon").toggleClass('flicker');
        });

        return false;
    });
});

function maintenance_adminbar() {
global $wp_admin_bar;

if( current_user_can( 'manage_options' ) ){
    if(get_option( 'maintenance' ) == true) {
        $wp_admin_bar->add_menu(array(
            'id' => 'maintenance',
            'title' => __('Maintenance') . get_option('maintenance'),
            'href' => '#',
            'meta' => array(
                'class' => 'maintenance-icon flicker'
            )
        ));
    } else {
        $wp_admin_bar->add_menu(array(
            'id' => 'maintenance',
            'title' => __('Maintenance') . get_option('maintenance'),
            'href' => '#',
            'meta' => array(
                'class' => 'maintenance-icon'
            )
        ));
    }
}

}
add_action('admin_bar_menu', 'maintenance_adminbar', 9999);