Alter comment pager to jump to comment section right away?

Question

I set up a content type and a specific comment type for this content. I set the comment pager to display 10 comments per page. When I now use the pager, I get redirected from the node URL itself www.domain.com/node/1, to www.domain.com/node/1?page=1.

Is there any possibility to add an ID to the URL for the comments pager only, for example www.domain.com/node/1?page=1#comments?

I want to do this, so the user doesn't need to scroll over the whole content of the node again, just to get to the second comments page. Instead, I want to jump to the comment section right away.

Is there any elegant way to do so? A module that does it, or similar? I already thought of altering the pager.html.twig in my theme. But then I would alter the node pager as well. Thank you very much in advance for pointing me any way to achieve this.

Answer 1

The only hook Drupal uses to alter a pager is hook_preprocess_pager() but that is invoked for every pager on any page, not just the pager used for comments.

The alternative is adding a new formatter for comments, which by default is the CommentDefaultFormatter class, and make it the default one with hook_field_info_alter().

function mymodule_field_info_alter(&$info) {
  // Change the default widget for fields of type 'comment'.
  if (isset($info['comment'])) {
    $info['comment']['default_formatter'] = 'mymodule_comment_formatter';
  }
}

(mymodule_comment_formatter is the formatter ID used in its annotation.)

The relevant code that sets the pager is in CommentDefaultFormatter::viewElements(), which contains the following lines.

if ($comments) {
  $build = $this->viewBuilder->viewMultiple($comments, $this->getSetting('view_mode'));
  $build['pager']['#type'] = 'pager';

  // CommentController::commentPermalink() calculates the page number
  // where a specific comment appears and does a subrequest pointing to
  // that page, we need to pass that subrequest route to our pager to
  // keep the pager working.
  $build['pager']['#route_name'] = $this->routeMatch->getRouteObject();
  $build['pager']['#route_parameters'] = $this->routeMatch->getRawParameters()->all();
  if ($this->getSetting('pager_id')) {
    $build['pager']['#element'] = $this->getSetting('pager_id');
  }
  $output['comments'] += $build;
}

Answer 2

You could use template_preprocess_pager(), but I am not sure you will be able to target one specific pager. You should check in $variables if there's any ID you can use to target the comment pager.