Respect "Prefers reduced motion" when users click on "Preview" when editing an issue

I can confirm it happens only with project issues; I could not reproduce the same with other content types. This means the observed behavior is not caused by Drupal core, but from custom code running on Drupal.org, or from code in the Project issue tracking module.

Since I didn't find anything in the custom code running on Drupal.org, the culprit should be the Project issue tracking module.
I apologize if I moved the issue in the wrong queue.

Yes, this is done with js/project-issue.js:

  /**
   * Jump to the actual preview and the form.
   */
  Drupal.behaviors.projectIssueJumpToNodeEditBlock = {
    attach: function () {
      $('#project-issue-ajax-form div.preview, #project-issue-ajax-form table.diff').once(function() {
        $('html, body').animate({scrollTop: $('#project-issue-ajax-form').offset().top});
      });
    }
  };

It seems the project branch is not passing tests because a Composer require failure. There isn't any link to the test results, so it's not clear what exactly is causing the failure.

I found the error on https://www.drupal.org/pift-ci-job/1138043, but I don't understand where that version constraint comes from.

--- Commands Executed ---
sudo -u www-data /usr/local/bin/composer require drupal/project_issue dev-2.x --prefer-source --prefer-stable --no-progress --no-suggest --no-interaction --working-dir /var/www/html
Return Code: 1
--- Output ---
--- Errors ---
[RuntimeException]
Could not load package drupal/project_issue in https://packages.drupal.org/7: [UnexpectedValueException] Could not parse version constraint !=2.0.0-unstable1: Invalid version string "2.0.0-unstable1"
[UnexpectedValueException]
Could not parse version constraint !=2.0.0-unstable1: Invalid version string "2.0.0-unstable1"

I went back to the discussion on the original implementation, #2192121: Previewing comments not possible, to see if there was a UX reason to use animate the scrolling. I’m not seeing any; I’m not seeing a good reason to keep the animation in any case.

Using window.location.hash = 'project-issue-ajax-form'; also sets the focussed element to the preview, which should be the right thing to do for accessibility, too.

(https://developer.mozilla.org/en-US/docs/Web/API/Element/scrollIntoView is an option too, reducing our dependency on jQuery is nice to have. It does offer animation in most browsers now, but does not respect prefers-reduced-motion on its own.)

I’ve deployed the non-animated version of this to www.drupal.org.

I also removed the Drupal.behaviors wrapper since this behavior will not need to be reapplied when the page changes.