Drupal8/jquery
Jquery isn't automatically included on every page by Drupal 8 (like D7), but the js file: libraries/civicrm/crm.drupal8.js assumes it is - i.e. it sez:
`// Need Drupal's jQuery to listen to this event jQuery(document).on('drupalToolbarTabChange', function(event, tab) {`
I'm getting js errors in my console on a contribution page, for example (Uncaught TypeError: jQuery is not a function)