Hide fields from print on rails admin

ui.js

//Put this file on app/assets/javascripts/rais_admin/custom/ui.js

// Hide elements from print
window.onload = function() {
  document.querySelector('div.well').className += ' hidden-print';
  document.querySelector('div.navbar-header').className += ' hidden-print';
  document.querySelector('ol.breadcrumb').className += ' hidden-print';
  document.querySelector('a.navbar-brand').className += ' hidden-print';
  document.querySelector('div.col-sm-3').className += ' hidden-print';
  document.querySelector('ul.nav-tabs').className += ' hidden-print';
  document.querySelector('a.pjax').className += ' hidden-print';
  document.querySelector('th.last').className += ' hidden-print';
  document.querySelector('th.shrink').className += ' hidden-print';
  $('table tbody tr td:last-child').addClass( 'hidden-print' );
  $('table tbody tr td:first-child').addClass( 'hidden-print' );
};