How to limit the number of nested fields

This script hides or shows the 'Add new' link depending on how many nested fields are already in the form for the specified association.

$(function() {
  // limits the number of categories
  $('#categories').on('cocoon:after-insert', function() {
    check_to_hide_or_show_add_link();
  });

  $('#categories').on('cocoon:after-remove', function() {
    check_to_hide_or_show_add_link();
  });

  check_to_hide_or_show_add_link();

  function check_to_hide_or_show_add_link() {
    if ($('#categories .nested-fields:visible').length == 5) {
      $('#add-category a').hide();
    } else {
      $('#add-category a').show();
    }
  }
})