WP_Customize_Nav_Menus::filter_wp_nav_menu() WordPress Method

	public function filter_wp_nav_menu( $nav_menu_content, $args ) {
		if ( isset( $args->customize_preview_nav_menus_args['can_partial_refresh'] ) && $args->customize_preview_nav_menus_args['can_partial_refresh'] ) {
			$attributes       = sprintf( ' data-customize-partial-id="%s"', esc_attr( 'nav_menu_instance[' . $args->customize_preview_nav_menus_args['args_hmac'] . ']' ) );
			$attributes      .= ' data-customize-partial-type="nav_menu_instance"';
			$attributes      .= sprintf( ' data-customize-partial-placement-context="%s"', esc_attr( wp_json_encode( $args->customize_preview_nav_menus_args ) ) );
			$nav_menu_content = preg_replace( '#^(<\w+)#', '$1 ' . str_replace( '\\', '\\\\', $attributes ), $nav_menu_content, 1 );
		}
		return $nav_menu_content;
	}