do_action( ‘wp_head’ )

User Contributed Notes

1. Skip to note 3 content

   Aurovrata Venet 7 years ago

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   taken from the old codex pages:

   function hook_css() {
       ?>
           <style>
               .wp_head_example {
                   background-color : #f1f1f1;
               }
           </style>
       <?php
   }
   add_action('wp_head', 'hook_css');

   or for inline scripts which need to be placed in the head,

   function hook_javascript() {
       ?>
           <script>
               alert('Page is loading...');
           </script>
       <?php
   }
   add_action('wp_head', 'hook_javascript');

   The wp_head() function which ones sees in all header.php files, is simply triggering the hook do_action(‘wp_head’). WordPress core files then hooks it multiple times to print the head,

   add_action( 'wp_head',             '_wp_render_title_tag',            1     );
   add_action( 'wp_head',             'wp_enqueue_scripts',              1     );
   add_action( 'wp_head',             'wp_resource_hints',               2     );
   add_action( 'wp_head',             'feed_links',                      2     );
   add_action( 'wp_head',             'feed_links_extra',                3     );
   add_action( 'wp_head',             'rsd_link'                               );
   add_action( 'wp_head',             'wlwmanifest_link'                       );
   add_action( 'wp_head',             'adjacent_posts_rel_link_wp_head', 10, 0 );
   add_action( 'wp_head',             'locale_stylesheet'                      );
   add_action( 'wp_head',             'noindex',                          1    );
   add_action( 'wp_head',             'print_emoji_detection_script',     7    );
   add_action( 'wp_head',             'wp_print_styles',                  8    );
   add_action( 'wp_head',             'wp_print_head_scripts',            9    );
   add_action( 'wp_head',             'wp_generator'                           );
   add_action( 'wp_head',             'rel_canonical'                          );
   add_action( 'wp_head',             'wp_shortlink_wp_head',            10, 0 );
   add_action( 'wp_head',             'wp_custom_css_cb',                101   );
   add_action( 'wp_head',             'wp_site_icon',                    99    );

   However, more interestingly you can also use it to add some meta tags,

   function hook_nocache() {
       ?>
     <meta http-equiv="cache-control" content="max-age=0" />
     <meta http-equiv="cache-control" content="no-cache" />
     <meta http-equiv="expires" content="0" />
     <meta http-equiv="expires" content="Tue, 01 Jan 1980 1:00:00 GMT" />
     <meta http-equiv="pragma" content="no-cache" />
       <?php
   }
   add_action('wp_head', 'hook_nocache');
2. Skip to note 4 content

   Nawawi Jamili 4 years ago

   You must log in to vote on the helpfulness of this noteVote results for this note: 0You must log in to vote on the helpfulness of this note

   Safe way to add HTML comment signature at the bottom page.

   add_action( 'wp_head', function() {
   	if ( ! is_user_logged_in() && ! defined( 'ADD_HTML_SIGNATURE' ) ) {
   		define( 'ADD_HTML_SIGNATURE', true );
   	}
   } );
   
   add_action( 'shutdown', function() {
   	if ( ! is_user_logged_in() && defined( 'ADD_HTML_SIGNATURE' ) ) {
   		echo "\n<!-- YOUR HTML SIGNATURE -->\n";
   	}
   }, 999 );

   • Warning: Do not use! The shutdown hook fires before PHP shuts down execution. It is always called, even in ajax requests, so this will immediately break your site.

     frzsombor 1 year ago