From 369a6754887a948830f2107602648e46cb370dfb Mon Sep 17 00:00:00 2001
From: gziolo <gziolo@git.wordpress.org>
Date: Mon, 2 Dec 2024 08:10:17 +0000
Subject: [PATCH] Interactivity API: Support length property on strings and
 arrays on the server

The Interactivity API tries to align client and server rendering so that the behavior is the same. Adds missing handling for `.length` to directives processing on the server on strings and numeric arrays which is inherently supported through JavaScript language on the client.

Props jonsurrell, gziolo, luisherranz.
Fixes #62582.


Built from https://develop.svn.wordpress.org/trunk@59477


git-svn-id: http://core.svn.wordpress.org/trunk@58863 1a063a9b-81f0-0310-95a4-ce76da25c4cd
---
 .../class-wp-interactivity-api.php            | 30 +++++++++++++++++++
 wp-includes/version.php                       |  2 +-
 2 files changed, 31 insertions(+), 1 deletion(-)

diff --git a/wp-includes/interactivity-api/class-wp-interactivity-api.php b/wp-includes/interactivity-api/class-wp-interactivity-api.php
index f6764736f9..8283349868 100644
--- a/wp-includes/interactivity-api/class-wp-interactivity-api.php
+++ b/wp-includes/interactivity-api/class-wp-interactivity-api.php
@@ -579,6 +579,36 @@ final class WP_Interactivity_API {
 		$path_segments = explode( '.', $path );
 		$current       = $store;
 		foreach ( $path_segments as $path_segment ) {
+			/*
+			 * Special case for numeric arrays and strings. Add length
+			 * property mimicking JavaScript behavior.
+			 *
+			 * @since 6.8.0
+			 */
+			if ( 'length' === $path_segment ) {
+				if ( is_array( $current ) && array_is_list( $current ) ) {
+					$current = count( $current );
+					break;
+				}
+
+				if ( is_string( $current ) ) {
+					/*
+					 * Differences in encoding between PHP strings and
+					 * JavaScript mean that it's complicated to calculate
+					 * the string length JavaScript would see from PHP.
+					 * `strlen` is a reasonable approximation.
+					 *
+					 * Users that desire a more precise length likely have
+					 * more precise needs than "bytelength" and should
+					 * implement their own length calculation in derived
+					 * state taking into account encoding and their desired
+					 * output (codepoints, graphemes, bytes, etc.).
+					 */
+					$current = strlen( $current );
+					break;
+				}
+			}
+
 			if ( ( is_array( $current ) || $current instanceof ArrayAccess ) && isset( $current[ $path_segment ] ) ) {
 				$current = $current[ $path_segment ];
 			} elseif ( is_object( $current ) && isset( $current->$path_segment ) ) {
diff --git a/wp-includes/version.php b/wp-includes/version.php
index 37d5f15239..8794e01161 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -16,7 +16,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '6.8-alpha-59476';
+$wp_version = '6.8-alpha-59477';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.