Prevent detection script injection from breaking import maps

westonruter · westonruter · commit fa03924d9502 · 2024-03-22T22:06:59.000-07:00
diff --git a/plugins/optimization-detective/optimization.php b/plugins/optimization-detective/optimization.php
@@ -10,6 +10,8 @@
 	exit; // Exit if accessed directly.
 }
 
+const OD_DETECTION_SCRIPT_PLACEHOLDER_COMMENT = '<!--OPTIMIZATION_DETECTIVE_DETECTION_SCRIPT-->';
+
 /**
  * Starts output buffering at the end of the 'template_include' filter.
  *
@@ -62,6 +64,12 @@ function od_maybe_add_template_output_buffer_filter() {
 		$callback = perflab_wrap_server_timing( $callback, 'optimization-detective', 'exist' );
 	}
 	add_filter( 'od_template_output_buffer', $callback );
+	add_action(
+		'wp_print_footer_scripts',
+		static function () {
+			echo OD_DETECTION_SCRIPT_PLACEHOLDER_COMMENT; // phpcs:ignore WordPress.Security.EscapeOutput.OutputNotEscaped
+		}
+	);
 }
 
 /**
@@ -340,13 +348,6 @@ function od_optimize_template_output_buffer( string $buffer ): string {
 	// Inject any preload links at the end of the HEAD. In the future, WP_HTML_Processor could be used to do this injection.
 	// However, given the simple replacement here this is not essential.
 	$head_injection = od_construct_preload_links( $lcp_elements_by_minimum_viewport_widths );
-
-	// Inject detection script.
-	// TODO: When optimizing above, if we find that there is a stored LCP element but it fails to match, it should perhaps set $needs_detection to true and send the request with an override nonce. However, this would require backtracking and adding the data-od-xpath attributes.
-	if ( $needs_detection ) {
-		$head_injection .= od_get_detection_script( $slug, $group_collection );
-	}
-
 	if ( $head_injection ) {
 		$buffer = preg_replace(
 			'#(?=</HEAD>)#i',
@@ -356,5 +357,15 @@ function od_optimize_template_output_buffer( string $buffer ): string {
 		);
 	}
 
+	// Inject detection script.
+	// TODO: When optimizing above, if we find that there is a stored LCP element but it fails to match, it should perhaps set $needs_detection to true and send the request with an override nonce. However, this would require backtracking and adding the data-od-xpath attributes.
+	if ( $needs_detection ) {
+		$buffer = str_replace(
+			OD_DETECTION_SCRIPT_PLACEHOLDER_COMMENT,
+			od_get_detection_script( $slug, $group_collection ),
+			$buffer
+		);
+	}
+
 	return $buffer;
 }
