do_action_ref_array( ‘send_headers’, WP $wp )

User Contributed Notes

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   Daniel Roch 2 years ago

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   Since WordPress 6.1, the send_headers action has been moved to later in core load. It is now triggered after pre_get_posts.

   Conditionals tags can now be used (is_single, is_404 and so on).

   More information on this dev-note: https://make.wordpress.org/core/2022/10/10/moving-the-send_headers-action-to-later-in-the-load/
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   Collins Mbaka 4 years ago

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   As an example: HTML5 Boilerplate provides an X-UA-Compatible meta element by default. This element breaks validation but can be moved to a header. Adding the following to functions.php fixes the validation issue and provides IE users a better experience.

   add_action( 'send_headers', 'add_header_xua' );
   function add_header_xua() {
   	header( 'X-UA-Compatible: IE=edge,chrome=1' );
   }
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   Steven Lin 4 years ago

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   Example migrated from Codex:

   As an example: HTML5 Boilerplate provides an X-UA-Compatible meta element by default. This element breaks validation, but can be moved to a header. Adding the following to functions.php fixes the validation issue and provides IE users a better experience.

   add_action( 'send_headers', 'add_header_xua' );
   function add_header_xua() {
   	header( 'X-UA-Compatible: IE=edge,chrome=1' );
   }
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   wp_kc 4 years ago

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   Example of how to conditionally send a header, replacing previously set header, if any…

   /**
    * Send "X-Robots-Tag: noindex, nofollow" header if not a public web site. 
    * If WP_DEBUG is true, treat web site as if it is non-public.
    */
   add_action( 'send_headers', function() {
   	if ( '0' != get_option( 'blog_public' ) || ( defined( 'WP_DEBUG' ) && true == WP_DEBUG ) ) {
   		/**
   		 * Tell robots not to index or follow
   		 * Set header replace parameter to true
   		 */
   		header( 'X-Robots-Tag: noindex, nofollow', true );
   	}
   }, 99 );  // Try to execute last with priority set to 99