WordPress: add maxlength to post/page/custom post type

<?php
//add maxlength to post/page/custom post type title field
add_action('admin_footer', 'add_maxlength_to_post_title');
function add_maxlength_to_post_title(){ ?>

    <script type="text/javascript">
        jQuery( function($){
            $('input#title').attr('maxlength', 30);
        });
    </script>

<?php }