Hide title if 404 error

Question

I have a custom 404 error page, and I just want a quick module that hides the 404 page title, if the user arrives at a 404 error.

I've found a D7 function that looks like it would work, checking for '404 Not Found' in the http header, and adding a class that I can target with CSS. But I'm not sure how I'd do something like this for D8.

Here's what I've got:

function MYMODULE_preprocess_html(&$variables) {
  $headers = drupal_get_http_header();

  if (isset($headers['status']) && $headers['status'] == '404 Not Found') {
    $variables['classes_array'][] = 'page-404';
  }
}

Answer 1

I don't think you need a custom module for something like this... This should be as easy as:

1. Go to Configuration -> System -> Basic Site Settings, get the page URL you have for the 404 page.

2. Go to Structure -> Block Layout, edit the 'Page Title' block, and exclude it under the Visibility section, by page URL from step1.

Answer 2

This should work:

/**
 * Implements hook_preprocess_HOOK().
 */
function modulename_preprocess_html(&$variables) {
  $status = \Drupal::requestStack()->getCurrentRequest()->attributes->get('exception');
  if($status && $status->getStatusCode() == '404') {
    if(!$variables['attributes']) {
      $variables['attributes'] = new Attribute();
    }
    $variables['attributes']->addClass('page-404');
  }
}

credits go to: How to check if the current page is a 404 error from a module/template?