wp_is_local_html_output() WordPress Function

function wp_is_local_html_output( $html ) {
	// 1. Check if HTML includes the site's Really Simple Discovery link.
	if ( has_action( 'wp_head', 'rsd_link' ) ) {
		$pattern = preg_replace( '#^https?:(?=//)#', '', esc_url( site_url( 'xmlrpc.php?rsd', 'rpc' ) ) ); // See rsd_link().
		return false !== strpos( $html, $pattern );
	}

	// 2. Check if HTML includes the site's Windows Live Writer manifest link.
	if ( has_action( 'wp_head', 'wlwmanifest_link' ) ) {
		// Try both HTTPS and HTTP since the URL depends on context.
		$pattern = preg_replace( '#^https?:(?=//)#', '', includes_url( 'wlwmanifest.xml' ) ); // See wlwmanifest_link().
		return false !== strpos( $html, $pattern );
	}

	// 3. Check if HTML includes the site's REST API link.
	if ( has_action( 'wp_head', 'rest_output_link_wp_head' ) ) {
		// Try both HTTPS and HTTP since the URL depends on context.
		$pattern = preg_replace( '#^https?:(?=//)#', '', esc_url( get_rest_url() ) ); // See rest_output_link_wp_head().
		return false !== strpos( $html, $pattern );
	}

	// Otherwise the result cannot be determined.
	return null;
}