Category : Optimisation

// header.php
<?php
if (is_home()) {
  echo'<h1>'; bloginfo( 'description' ); echo'</h1>';
} else {
  echo'<h2>'; bloginfo( 'description' ); echo'</h2>';
} ?>

// functions.php
  wp_deregister_script( 'jquery' ); // On annule l'inscription du jQuery de WP
  wp_enqueue_script( // On déclare une version plus moderne
    'jquery', 
    'https://cdnjs.cloudflare.com/ajax/libs/jquery/3.5.1/jquery.min.js', 
    false, 
    '3.5.1', 
    true 
  );
}
add_action( 'wp_enqueue_scripts', 'sp_register_assets' );

// functions.php
function sp_clean_body_classes( $classes ) {
  $allowed_classes = [
    'home',
    'page-homepage','homepage',
    'page-template-landing-page',
    'page-template-home',
    'page-template-default',
    'singular',
    'single',
    'page',
    'archive',
  ];
  return array_intersect( $classes, $allowed_classes );
}
add_filter( 'body_class', 'sp_clean_body_classes', 20 );

// functions.php
function dequeue_jquery_migrate( &$scripts ){
  if( !is_admin() ) {
    $scripts->remove( 'jquery');
    $scripts->add( 'jquery', false, array( 'jquery-core' ), '1.10.2' );
  }
}
add_filter( 'wp_default_scripts', 'dequeue_jquery_migrate' );

Read : Reasons to dequeue this script

// functions.php
function sp_add_slug_body_class( $classes ) {
  global $post;
  if ( isset( $post ) ) {
    $classes[] = $post->post_type . '-' . $post->post_name;
  }
  return $classes;
}
add_filter( 'body_class', 'sp_add_slug_body_class' );;

// functions.php
function clean_post_classes( $classes ) {
  if( ! is_array( $classes ) )
    return $classes;
    $allowed_classes = array(
      'hentry',
      'type-' . get_post_type(),
    );
    return array_intersect( $classes, $allowed_classes );
}
add_filter( 'post_class', 'clean_post_classes', 5 );

// functions.php
function clean_nav_menu_classes( $classes ) {
  if( ! is_array( $classes ) )
     return $classes;
  foreach( $classes as $i => $class ) {
    // Remove class with menu item id
    $id = strtok( $class, 'menu-item-' );
    if( 0 < intval( $id ) )
      unset( $classes[ $i ] );
    // Remove menu-item-type-*
    if( false !== strpos( $class, 'menu-item-type-' ) )
       unset( $classes[ $i ] );
    // Remove menu-item-object-*
    if( false !== strpos( $class, 'menu-item-object-' ) )
      unset( $classes[ $i ] );
    // Change page ancestor to menu ancestor
    if( 'current-page-ancestor' == $class ) {
      $classes[] = 'current-menu-ancestor';
      unset( $classes[ $i ] );
    }  
  }

  // Remove submenu class if depth is limited
  if( isset( $args->depth ) && 1 === $args->depth ) {
    $classes = array_diff( $classes, array( 'menu-item-has-children' ) );
  }
  return $classes;
}
add_filter( 'nav_menu_css_class', 'clean_nav_menu_classes', 5 );

// functions.php
function singular_body_class( $classes ) {
  if( is_singular() )
    $classes[] = 'singular';
  return $classes;
}
add_filter( 'body_class', 'singular_body_class' );

// function.php
// Alter dns-prefetch links
add_filter('wp_resource_hints', function (array $urls, string $relation): array {
    // If the relation is different than dns-prefetch, leave the URLs intact
    if ($relation !== 'dns-prefetch') {
        return $urls;
    }
    // Remove s.w.org entry
    $urls = array_filter($urls, function (string $url): bool {
        return strpos($url, 's.w.org') === false;
    });
    return array_merge($urls);
}, 10, 2);

// Remove infos about WordPress version
remove_action('wp_head', 'wp_generator');

// Remove emoji script and styles
remove_action('wp_head', 'print_emoji_detection_script', 7);
remove_action('wp_print_styles', 'print_emoji_styles');

// Remove REST-API link
remove_action('wp_head', 'rest_output_link_wp_head');

// Disable XML-RPC
add_filter('xmlrpc_enabled', function (): bool {
    return false;
});

// Remove XML-RPC link
remove_action('wp_head', 'rsd_link');

// Remove Windows Live Writer manifest
remove_action('wp_head', 'wlwmanifest_link');

// Disable RSS feeds by redirecting their URLs to homepage
foreach (['do_feed_rss2', 'do_feed_rss2_comments'] as $feedAction) {
    add_action($feedAction, function (): void {
        // Redirect permanently to homepage
        wp_redirect(home_url(), 301);
        exit;
    }, 1);
}

// Remove the feed links
remove_action('wp_head', 'feed_links', 2);

// Remove unnecessary attributes from style tags
add_filter('style_loader_tag', function (string $tag, string $handle): string {
  // Remove ID attribute
  $tag = str_replace("id='${handle}-css'", '', $tag);
  // Change ' to " in attributes:
  $tag = str_replace('\'', '"', $tag);
  // Remove trailing slash
  $tag = str_replace(' />', '>', $tag);
  // Remove double spaces
  return str_replace('  ', '', $tag);
}, 10, 2);