fix: hide debug HTML comments in REST and Ajax responses

Author: jom

wp-cache-phase2.php

@@ -2210,7 +2210,14 @@ function wp_cache_append_tag( &$buffer ) {
 		$msg = "Live page served on $timestamp";
 	}
 
-	if ( strpos( $buffer, '<html' ) === false ) {
+	// Don't output debug message if we aren't handling a normal HTML response.
+	if (
+		strpos( $buffer, '<html' ) === false ||
+		( defined( 'REST_REQUEST' ) && REST_REQUEST ) ||
+		( defined( 'JSON_REQUEST' ) && JSON_REQUEST ) ||
+		( defined( 'WC_API_REQUEST' ) && WC_API_REQUEST ) ||
+		( function_exists( 'wp_doing_ajax' ) && wp_doing_ajax() )
+	) {
 		wp_cache_debug( site_url( $_SERVER['REQUEST_URI'] ) . ' - ' . $msg );
 		return false;
 	}
@@ -2229,7 +2236,14 @@ function wp_cache_add_to_buffer( &$buffer, $text ) {
 		return false;
 	}
 
-	if ( strpos( $buffer, '<html' ) === false ) {
+	// Don't output debug message if we aren't handling a normal HTML response.
+	if (
+		strpos( $buffer, '<html' ) === false ||
+		( defined( 'REST_REQUEST' ) && REST_REQUEST ) ||
+		( defined( 'JSON_REQUEST' ) && JSON_REQUEST ) ||
+		( defined( 'WC_API_REQUEST' ) && WC_API_REQUEST ) ||
+		( function_exists( 'wp_doing_ajax' ) && wp_doing_ajax() )
+	) {
 		wp_cache_debug( site_url( $_SERVER['REQUEST_URI'] ) . ' - ' . $text );
 		return false;
 	}