Fix: hide debug HTML comments in REST and Ajax responses (#1021)

kraftbj · jom · donnchawp · web-flow · commit 1c6e7e2ea480 · 2026-05-27T17:43:46.000+01:00
* fix: hide debug HTML comments in REST and Ajax responses

* fix: clarify debug comment suppression messages

* Extract wpsc_skip_debug_output() to de-duplicate the non-HTML response check

The REST/Ajax/JSON/WC bail condition was copy-pasted into both wp_cache_append_tag() and wp_cache_add_to_buffer(). Move it into a single named predicate so the two call sites can't drift, and drop the explanatory comment the inline condition needed.

* Also skip debug comments on XML-RPC requests

advanced-cache.php already treats XMLRPC_REQUEST as a non-HTML response type; keep wpsc_skip_debug_output() consistent so XML-RPC bodies stay clean regardless of the &lt;html sniff.

---------

Co-authored-by: Jake Morrison &lt;68693+jom@users.noreply.github.com&gt;
Co-authored-by: Donncha O Caoimh &lt;5656673+donnchawp@users.noreply.github.com&gt;
diff --git a/wp-cache-phase2.php b/wp-cache-phase2.php
@@ -2196,6 +2196,15 @@ function wp_cache_ob_callback( $buffer ) {
 	}
 }
 
+function wpsc_skip_debug_output( $buffer ) {
+	return strpos( $buffer, '<html' ) === false ||
+		( defined( 'REST_REQUEST' ) && REST_REQUEST ) ||
+		( defined( 'JSON_REQUEST' ) && JSON_REQUEST ) ||
+		( defined( 'WC_API_REQUEST' ) && WC_API_REQUEST ) ||
+		( defined( 'XMLRPC_REQUEST' ) && XMLRPC_REQUEST ) ||
+		( function_exists( 'wp_doing_ajax' ) && wp_doing_ajax() );
+}
+
 function wp_cache_append_tag( &$buffer ) {
 	global $wp_cache_gmt_offset, $wp_super_cache_comments;
 	global $cache_enabled, $super_cache_enabled;
@@ -2215,7 +2224,7 @@ function wp_cache_append_tag( &$buffer ) {
 		$msg = "Live page served on $timestamp";
 	}
 
-	if ( strpos( $buffer, '<html' ) === false ) {
+	if ( wpsc_skip_debug_output( $buffer ) ) {
 		wp_cache_debug( site_url( $_SERVER['REQUEST_URI'] ) . ' - ' . $msg );
 		return false;
 	}
@@ -2234,7 +2243,7 @@ function wp_cache_add_to_buffer( &$buffer, $text ) {
 		return false;
 	}
 
-	if ( strpos( $buffer, '<html' ) === false ) {
+	if ( wpsc_skip_debug_output( $buffer ) ) {
 		wp_cache_debug( site_url( $_SERVER['REQUEST_URI'] ) . ' - ' . $text );
 		return false;
 	}

Original file line number	Diff line number	Diff line change
`@@ -2196,6 +2196,15 @@ function wp_cache_ob_callback( $buffer ) {`
`2196`	`2196`	`}`
`2197`	`2197`	`}`
`2198`	`2198`
	`2199`	`+function wpsc_skip_debug_output( $buffer ) {`
	`2200`	`+ return strpos( $buffer, '<html' ) === false \|\|`
	`2201`	`+ ( defined( 'REST_REQUEST' ) && REST_REQUEST ) \|\|`
	`2202`	`+ ( defined( 'JSON_REQUEST' ) && JSON_REQUEST ) \|\|`
	`2203`	`+ ( defined( 'WC_API_REQUEST' ) && WC_API_REQUEST ) \|\|`
	`2204`	`+ ( defined( 'XMLRPC_REQUEST' ) && XMLRPC_REQUEST ) \|\|`
	`2205`	`+ ( function_exists( 'wp_doing_ajax' ) && wp_doing_ajax() );`
	`2206`	`+}`
	`2207`	`+`
`2199`	`2208`	`function wp_cache_append_tag( &$buffer ) {`
`2200`	`2209`	`global $wp_cache_gmt_offset, $wp_super_cache_comments;`
`2201`	`2210`	`global $cache_enabled, $super_cache_enabled;`
`@@ -2215,7 +2224,7 @@ function wp_cache_append_tag( &$buffer ) {`
`2215`	`2224`	`$msg = "Live page served on $timestamp";`
`2216`	`2225`	`}`
`2217`	`2226`
`2218`		`- if ( strpos( $buffer, '<html' ) === false ) {`
	`2227`	`+ if ( wpsc_skip_debug_output( $buffer ) ) {`
`2219`	`2228`	`wp_cache_debug( site_url( $_SERVER['REQUEST_URI'] ) . ' - ' . $msg );`
`2220`	`2229`	`return false;`
`2221`	`2230`	`}`
`@@ -2234,7 +2243,7 @@ function wp_cache_add_to_buffer( &$buffer, $text ) {`
`2234`	`2243`	`return false;`
`2235`	`2244`	`}`
`2236`	`2245`
`2237`		`- if ( strpos( $buffer, '<html' ) === false ) {`
	`2246`	`+ if ( wpsc_skip_debug_output( $buffer ) ) {`
`2238`	`2247`	`wp_cache_debug( site_url( $_SERVER['REQUEST_URI'] ) . ' - ' . $text );`
`2239`	`2248`	`return false;`
`2240`	`2249`	`}`